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The geographic scale of speciation in a marine snail with high dispersal potential
Abstract
Aim We use the Stramonita haemastoma species complex (Muricidae) to investigate the geographic scale of speciation in a marine snail with a long pelagic larval duration (PLD) of 2–3 months and, consequently, high dispersal potential. We aim to: (1) delimit species within Stramonita, (2) discover the phylogenetic relationship among them, (3) map their distributions, and (4) infer the age and likely cause of speciation events.
Location Tropical intertidal of the Atlantic and eastern Pacific Oceans.
Methods We use one nuclear and two mitochondrial genes to construct a molecular phylogeny of the S. haemastoma species complex. We first test the monophyly of the genus and of the species complex, and then use statistical methods to delimit species within the complex. We incorporate information from museum collections and the literature to map distributions and to look for diagnostic morphological traits. We use fossils to date our phylogeny.
Results The genus Stramonita is monophyletic and restricted to the tropical and warm-temperate Atlantic and eastern Pacific oceans. The genus is composed of Stramonita delessertiana and six members of the S. haemastoma complex: S. haemastoma, Stramonita rustica, Stramonita floridana, Stramonita canaliculata, Stramonita biserialis and Stramonita brasiliensis (new species described herein). These species are supported by reciprocal monophyly in mitochondrial gene trees, together with independent evidence from morphology, distribution and the nuclear gene. The species are almost entirely allopatric, with only three instances of sympatry. Two species have unusually wide distributions, consistent with their long PLD; one of these is amphi-Atlantic.
Main conclusions Despite the long PLD of Stramonita, speciation has occurred within the Atlantic, both in response to barriers operating at the largest geographical scale (the width of Atlantic, but not the Amazon barrier) and at a smaller scale within the western Atlantic.
... Numerous cryptic species of gastropod were discovered through molecular analysis such as Thais keluo, Conus peasei, Gemmuloborsonia clandestine, Naranjia sp, Crepipatella (Lawler and Duda 2017;Nantarat et al. 2019;Puillandre et al. 2010;Saito et al. 2020;Tan and Liu 2001;Véliz et al. 2012;Véliz et al. 2003). The discovered cases of marine cryptic species has raised a number of questions about their status Tahani El Ayari tahaniayari@yahoo.fr 1 The age of the S. haemastoma complex was being estimated to be 28 Ma (Claremont et al. 2011). All S. haemastoma species complex are allopatric; however three cases of sympatry have been reported between S. haemastoma, S. brasiliensis and S. rustica in Venezuela; S. floridana and S. canaliculata in the Gulf of Mexico; and S. Rustica and S. brasiliensis in Brazil. ...
... In a recent study, El Ayari et al. (2017) investigated the genetic structure of S. haemastoma collected from 20 localities in the Western Mediterranean Sea (Pramousquier, Thau, (France), Tarragona, Castellon, Borriana, Torreveija, Almeria, (Spain), Oran, Annaba (Algeria), Tabarka, Bizerte, Korbous, Kélibia, Houaria, (Tunisia), Palermo (Italy) and North-Eastern Atlantic Ocean (Arcachon Bay, (France), Faro, Cádiz (Portugal), Casablanca, Essaouira (Morocco)) using mitochondrial and nuclear loci; results from this study revealed the occurrence of two cryptic lineages with a mosaic distribution and a hybrid zone along the Mediterranean Spanish coasts. The Mediterranean and Atlantic cryptic lineages reported by El Ayari et al. (2017) were also detected in Senegal, Venezuela, Murcia, Isla de Alborán and Macaronesian islands samples from Claremont et al. (2011). More recently, Pezy et al. (2019) recorded a new introduction of three specimens morphologically identified as S. haemastoma in the English Channel. ...
... In this study, shell features together with mitochondrial DNA COI sequence of Stramonita sampled from Accra, Ghana (Eastern Atlantic) were investigated. Morphological and mitochondrial DNA COI sequences were analyzed with data from El Ayari et al. (2017), Claremont et al. (2011) and Genbank. ...
Several cryptic (new) species were recently identified based on molecular data. Phylogenetic analyses of Stramonita haemastoma complex have recognized new species and cryptic lineages. In the present study, we recorded of the first time the occurrence of a new species from a rocky shore located in Accra, Ghana, Eastern Atlantic Ocean. Individuals from Accra, Ghana (Eastern Atlantic Ocean) were firstly identified as S. haemastoma based on morphological criteria. The colour pattern of the aperture and the number of crenulations were examined from the identification of Ghanaian species, moreover comparison with S. haemastoma shell features was conducted. Molecular analysis of the mitochondrial DNA COI sequence of specimens from Ghana showed a strong divergence from Stramonita haemastoma species, this finding was proved by statistical analysis. Overall, the mean genetic distance calculated between S. haemastoma and Ghanaian population is high 10%. The genetic distance measured between Ghanaian Stramonita and other species of the Stramonita haemastoma complex were ranged from 4% S. brasiliensis and 12% S. canaliculata. Specimens from Ghana represent a new species of Stramonita not yet described in Accra coast, Ghana, Eastern Atlantic.
... In addition, populations of A. hotessierianum and A. viridulum separated by the tropical gap also show morphological differences in their shells and radulae (Dornellas et al., 2021). Population genetic studies of marine mollusks in the Brazilian Biogeographical Province have increased over the last decade, providing insights into species delimitation, cryptic species and polymorphic species (Arruda et al., 2009;Barroso et al., 2020;Claremont et al., 2011;Lazoski et al., 2011;Padula et al., 2016;Sales et al., 2013;Trovant et al., 2016). However, no studies have yet addressed connectivity patterns within the Brazilian Province. ...
... The Orinoco/Amazon barrier seems to drive speciation for several coastal taxa, including reef fishes, lobsters and mussels (Floeter et al., 2008;Rocha, 2003;Tourinho et al., 2012;Trovant et al., 2016). On the other hand, many reef fishes show high genetic connectivity between populations to either side of the Orinoco/Amazon (Floeter et al., 2008;Liedke et al., 2020;Rocha et al., 2005), as do some invertebrates, including the marine gastropods Stramonita and Neritina (Barroso et al., 2020;Claremont et al., 2011). The existence of truly marine ecosystems located off the Amazon's mouth at depths below the influence of the river plume may act as a corridor for many species adapted to subtidal conditions (Cordeiro et al., 2015;Moura et al., 1999Moura et al., , 2016. ...
... However, even invertebrates with long pelagic larval duration sometimes diversify within the Atlantic basin. Despite a long pelagic larval duration of 2-3 months, a complex of Stramonita haemastoma species has speciated within the Atlantic both in response to barriers operating at the largest geographical scale, the width of Atlantic (although not the Amazon barrier) and at a smaller scale within the western Atlantic (see also Strombus, Claremont et al., 2011;Latiolais et al., 2006). ...
The rocky intertidal gastropods Agathistoma viridulum and A. hotessierianum occur from the Caribbean to southern Brazil, with a gap in the equatorial region, giving them an anti-tropical distribution. We used sequences from mitochondrial genes to elucidate the phylogeography of A. viridulum and A. hotessierianum and to infer their relationships to other species of Agathistoma. For A. hotessierianum, haplotype networks and phylogenetic analyses split samples into two distinct groups: one (A. hotessierianum) in the Caribbean region (Greater and Lesser Antilles; Venezuela: Sucre and Isla Margarita) and a new species that we describe from northeastern Brazil. For A. viridulum, genetic analyses split the samples into three groups (Caribbean, northeastern Brazil and southeastern Brazil), but genetic divergence among these was too low for them to be considered species, and morphological differences were not significant. The mtDNA tree identified two clades of eastern Pacific Agathistoma, but many lower-level relationships within Agathistoma were not well resolved, suggesting that more complete taxon sampling and additional genetic data will be needed to establish more robust relationships among Tegulinae.
... Ceci s'explique par la préférence de cette espèce pour des profondeurs comprises entre 100 et 400 m. Les dragages au cours de cette campagne n'ont pas dépassé 90 m. Claremont & Reid, 2011 (pl. VI, fig. ...
... 10-11) MNHN IM-2013-71357-71358, 71360, Baie du Galion, stn AM032, à 0 m, (Bold : MUBA758-18, GenBank : MK216519). Commentaire : Cette espèce a été identifiée à la suite d'analyses phylogénétiques sur le complexe d'espèces apparentées à Stramonita haemastoma (Linnaeus, 1767) (Claremont et al., 2011). Le séquençage de plusieurs spécimens, d'abord en Guadeloupe et maintenant en Martinique confirme la présence de S. brasiliensis dans les Antilles Françaises. ...
... 12-13) MNHN IM-2013-71355 (Bold : MUBA764-18, GenBank : MK216527), Baie du Galion, stn AM032, à 0 m ; IM-2013-71356, 71359, Baie du Galion, stn AM032, à 0 m. Commentaire : Une larve planctonique de très longue durée de vie (entre 2 et 3 mois) explique le très fort potentiel de dispersion de Stramonita haemastoma (Claremont et al., 2011). Sa répartition s'étend du Bassin Méditerranéen aux côtes d'Afrique de l'Ouest, aux Açores et jusqu'au Venezuela. ...
Inventaire des Muricidae récoltés au cours de la campagne MADIBENTHOS du MNHN en Martinique (Antilles Françaises) et description de 12 nouvelles espèces des genres Dermomurex, Attilosa, Acanthotrophon, Favartia, Muricopsis et Pygmaepterys (Mollusca, Gastropoda).
... Females lay 20-86 egg capsules each containing 1,700-7,000 eggs (Lahbib, Abidli, & El Menif, 2011). The size of the protoconch (larval shell retained on the adult shell) as well as the duration of larval development in the laboratory allowed to estimate a larval pelagic duration of 2-3 months (Claremont et al., 2011, El Ayari, 2015Lahbib et al., 2011;Appeltans et al., 2012). Such extremely long-lived larvae capable of dispersal over long distances are usually called "teleplanic" (Scheltema, 1971). ...
... Such extremely long-lived larvae capable of dispersal over long distances are usually called "teleplanic" (Scheltema, 1971). Stramonita haemastoma is a complex of species with widespread distribution in the Atlantic Ocean and Eastern Pacific Ocean (Abbott, 1972;Claremont et al., 2011, Clench, 1947. Claremont, Williams, Barraclough, and Reid (2011) conducted a study on the genus Stramonita which identified, in addition to the previously recognized outgroup Pacific species S. delessertiana, six members in the Stramonita haemastoma complex, S. biserialis in the South-Eastern Pacific Ocean, S. floridana and S. canaliculata in the North-Western Atlantic Ocean, S. rustica and S. brasiliensis in the South-Western Atlantic Ocean, and S. haemastoma. ...
... Stramonita haemastoma is a complex of species with widespread distribution in the Atlantic Ocean and Eastern Pacific Ocean (Abbott, 1972;Claremont et al., 2011, Clench, 1947. Claremont, Williams, Barraclough, and Reid (2011) conducted a study on the genus Stramonita which identified, in addition to the previously recognized outgroup Pacific species S. delessertiana, six members in the Stramonita haemastoma complex, S. biserialis in the South-Eastern Pacific Ocean, S. floridana and S. canaliculata in the North-Western Atlantic Ocean, S. rustica and S. brasiliensis in the South-Western Atlantic Ocean, and S. haemastoma. The latter is the single representative of the species complex in the Eastern Atlantic, and Mediterranean Sea although molecular data were mostly lacking for Mediterranean samples. ...
Molecular approaches have proven efficient to identify cryptic lineages within single taxonomic entities. Sometimes these cryptic lineages maybe previously unreported or unknown invasive taxa. The genetic structure of the marine gastropod Stramonita haemastoma has been examined in the Western Mediterranean and North-Eastern Atlantic populations with mtDNA COI sequences and three newly developed microsatellite markers. We identified two cryptic lineages, differentially fixed for alternative mtDNA COI haplogroups and significantly differentiated at microsatellite loci. The mosaic distribution of the two lineages is unusual for a warm-temperate marine invertebrate with a teleplanic larval stage. The Atlantic lineage was unexpectedly observed as a patch enclosed in the north of the Western Mediterranean Sea between eastern Spain and the French Riviera, and the Mediterranean lineage was found in Macronesian Islands. Although cyto-nuclear disequilibrium is globally maintained, asymmetric introgression occurs in the Spanish region where the two lineages co-occur in a hybrid zone. A first interpretation of our results is mito-nuclear discordance in a stable postglacial hybrid zone. Under this hypothesis, though, the location of genetic discontinuities would be unusual among planktonic dispersers. An alternative interpretation is that the Atlantic lineage, also found in Senegal and Venezuela, has been introduced by human activities in the Mediterranean area and is introgressing Mediterranean genes during its propagation, as theoretically expected. This second hypothesis would add an additional example to the growing list of cryptic marine invasions revealed by molecular studies.
... As reported by Clench (1947), the shells' morphological variations suggest an enormous ambiguity that indicates marked overlay. The reason is that certain environmental factors that intertidal gastropods are exposed to hamper the use of its external morphology for taxonomic identification (Liu et al., 1991;Kool, 1993;Vermeij 2001;Claremont et al., 2011). The two mitochondrial genes used in this study were effective in distinguishing both species as taxonomically distinct units with large genetic distances. ...
... Layton et al. (2014), analyzing the COI gene, used the threshold of 2% to delimitate species of molluscs. Claremont et al. (2011), working with Stramonita, obtained pairwise distances within species of 1.9% for S. rustica, 1.8% for S. haemastoma, 1.3% for S. floridana, and 0.8% for S. brasiliensis, and sequence divergence among species ranging from 6.8% to 12.0%. Other genetic and molecular sequences comparison approaches have been used in different studies to identify the occurrence of two sympatric and genetically distinct groups of S. haemastoma in Brazil (Udelsmann, 2009, Master of Science Thesis, UNICAMP, Campinas, Brazil). ...
... Our results corroborate the findings of Claremont et al. (2011), which confirm the occurrence of the S. brasiliensis along the Brazilian coast. Claremont et al. (2011) also reported that S. floridana only inhabits the south Atlantic region of the United States and suggested that the S. rustica species occurs with S. brasiliensis along the Brazilian coast. ...
Snails of the genus Stramonita are commonly found in the rocky intertidal habitat of the western Atlantic Ocean coast. They belong to a monophyletic taxon that occurs along the tropical and warm-temperate Atlantic and eastern Pacific rocky shores. This genus comprises different valid species and members of the S. haemastoma complex. In the present study, samples of Stramonita were collected from three different regions of southeastern Brazil. Partial sequences of two mitochondrial genes, COI and 16S rRNA, were used to compare nucleotides sequences between Stramonita specimens. Levels of nucleotide divergence greater than 2% across the three sampled regions were used for differentiation at the species level. One of the identified species was S. brasiliensis, which has recently been described by molecular analysis; the other species may represent S. haemastoma, not yet described in the southeastern Brazilian coast.
... The snail Stramonita brasiliensis (Claremont et al., 2011) is a species of ecological and economic relevance, constantly exposed to salinity variations while moving around through different microhabitats on rocky shores. As this species occupies upper intertidal zones, where it is frequently exposed to salinity increase through evaporation and decrease through freshwater input during low tides, we investigated its tolerance to both high and low extremes of salinity. ...
... Stramonita brasiliensis occupies a wide tidal range on tropical rocky shores along the Atlantic coast of South America, between Colombia and Uruguay (Claremont et al., 2011). This snail is a predator both in the wild and in bivalve cultures (Garton & Stickle, 1980;Butler, 1985;Brown, 1997). ...
... In addition it is a food species for humans and there is research targeted at improving its production (Manzoni & Lacava, 1998). The genus Stramonita was previously considered a synonym of Thais (Kool, 1993;Vermeij, 2001) and the Brazilian species was formerly classified as S. haemastoma, recently shown to be a complex of six species (Claremont et al., 2011). ...
Stramonita brasiliensis is a marine intertidal gastropod, an active predator, constantly exposed to salinity variations in its intertidal rocky habitat.
The goal of this study was to investigate whether the species would handle salinity increase as well as salinity decrease,
given the general paucity of data on molluscs in hypersaline seawater. Snails from Santa Catarina State, southern Brazil,
were exposed to abrupt (from full-strength seawater to freshwater or to 70 psu) or gradual (full-strength seawater down to
freshwater or up to 70 psu) salinity challenges. The isolated muscular foot was challenged with hypo- and hyperosmotic shocks,
both of 50% with respect to the isosmotic control. Behaviour (release from the substrate and operculum closure), mantle cavity
water and haemolymph osmo-ionic concentrations, and tissue hydration were then assayed. When abruptly exposed, snails remained
open and active in hypersaline seawater (until 55 psu), but tended to close the operculum upon seawater dilution (salinity
15 psu). In agreement, tissues swelled more in hyposmotic saline than they shrank in hyperosmotic saline. The great euryhalinity
displayed by this snail may contribute to its widespread distribution on intertidal rocky coasts.
... Genetic differences in marine organisms between different geographical populations are often influenced by ocean currents, 28,33 dispersal capacity, 4 environmental tolerance and substrate and the interaction between these factors. 34,35 It is well known that the Bohai Sea, a semi-enclosed sea, has a relatively low water exchange rate with the Yellow Sea, 36,37 which to some extent hinders the migration of A. pectinate larvae from the Bohai Sea to the Yellow Sea, which may be the main reason for the separation of the RZ population from the CD and DL populations. Similar results have also been reported in other marine bivalves, including Scapharca broughtonii 5 and Chlamys farreri. ...
... 44 In addition, the geographical barriers caused by primary production, freshwater influence and turbidity are all present on continental margins and around high islands, which has implications for the effectiveness of barriers to larval dispersal. 34,45 However, A. pectinate could live down to depths of 100m, 4 so its larval dispersal might be less affected by the ecological or hydrographical barriers. Therefore, the larvae of A. pectinate from the ESC could overcome the barriers caused by the freshwater discharge of the Yangtze River and migrate to the Yellow Sea. ...
Background
An ecologically and economically important species in East Asia, the natural resources of pen shell Atrina pectinate have suffered severe population declines due to habitat destruction, pollution, and overfishing. Assessing genetic diversity and population structure is the basis for establishing conservation programs for A. pectinate .
Results
Our data indicated that high genetic diversity was found in all six populations, with mean allelic richness ( Ar ) ranging from 8.255 to 9.734, mean observed heterozygosity ( Ho ) from 0.574 to 0.680, and mean expected heterozygosity ( He ) from 0.620 to 0.691. The five A. pectinate populations were divided into two clusters. This clustering result was partly consistent with their geographical origin; the RZ population did not cluster with the northern populations (DL, CD), suggesting that there is no genetic divergence and geographical differentiation between the North China Sea (CD, DL, and RZ) and the Southeast China Sea (HK and ST).
Conclusion
Our results show no significant genetic differentiation between samples from the North China Sea and the Southeast China Sea. High dispersal potential of larvae by passive drift with ocean currents may explain the lack of genetic differentiation between samples. The results suggest a weak level of genetic structure in A. pectinate with a long planktonic larval stage.
... In general, our results agreed with the theoretical premises: species with planktonic (planktotrophic and lecithotrophic) larvae have a greater dispersive capacity and, therefore, broader geographic distributions than species with non-planktonic larvae (intracapsular metamorphosis) (Thorson 1950;Scheltema 1971;Berger 1973;Lutz 1980, 1983;Gilinsky 1981;Myers et al. 2000;Collin 2001;Guzmán et al. 2011). These broader geographic distributions of species with planktotrophic larvae (recorded on both sides of the Orinoco-Amazon freshwater outflow Barrier and, sometimes, also in the Eastern Atlantic Ocean) may result from a long period of pelagic larval duration (PLD), which could provide both a greater ability to cross large barriers of inadequate substrate and colonization of oceanic islands, promoting a wider distribution of the species (Claremont et al. 2011). The dispersal capacity can also be increased Fig. 2 Relationship between the geographical distribution range of marine gastropods (in degrees of latitude) and their larval and adult characteristics (larval development type, depth ranges, and number of used habitats). ...
... Along with these factors, studies have shown that the ecological conditions required by larvae and adults of each species interfere in their dispersal capabilities and, consequently, in their geographic distributions (e.g., Scheltema 1989;Bhaud 1993;Andrade et al. 2003;Fortunato 2004;Bird et al. 2011;Claremont et al. 2011;Albaina et al. 2012). These ecological requirements could explain, for example, the restricted geographical distribution of species with planktotrophic larvae (e.g., Crepidula argentina Simone, Pastorino &Penchaszadeh, 2000, andCrepidula depressa Say, 1822). ...
The larval stage is a critical aspect of the biology of most marine animals, impacting not only the species fitness but also its bathymetric and geographic distribution. To understand the role of larval dispersion and adult characteristics in the distribution of marine gastropods, the present study assesses the relationship among larval development type (planktotrophic, lecithotrophic, or intracapsular metamorphosis), adult characteristics (body size, depth range, and habitat diversity), and geographic distribution of benthic gastropods inhabiting shallow waters (up to 200 m depth) in the Western Atlantic Ocean. Results were generated using literature and linear mixed model (LMM) and variance partition analyses. Larval development type is the most important predictor of geographical distribution of marine gastropods analyzed here, unlike studies with reef fishes. Along with the type of larval development, the ability to occupy different types of habitats and depth ranges were also important to predict the geographic distribution, but to a lesser extent. The similar dispersal capabilities of planktotrophic and lecithotrophic larvae and the restricted geographic distribution of some species with planktonic larvae are also discussed.
... Imposex is is a well-documented deleterious effect caused by tributyltin (TBT) in females of hundreds of Caenogastropoda species and it is a well-established way of predicting BTs occurrence in marine systems. This study presents the very first information on the presence and distribution of imposex in Stramonita brasiliensis (Claremont and Reid, 2011) in the Brazilian Legal Amazon, within a Ramsar site, during a 6-year appraisal after the TBT global ban in 2008 (2012-2017). Imposex was evidenced in six out of the seven sampling sites, with 39.7% of the total affected females, most of them showing VDSI <1. ...
... It is a lowcost technique and has a biologically meaningful measurement that reveals the effects of this pollutant on an ecosystem at the individual, population, and community levels (Rossato et al., 2018). Stramonita brasiliensis (Claremont et al., 2011) is a suitable indicator to be used in studies aiming to evaluate TBT pollution, since no reports of imposex induced by other factors are known for this specie (Rossato et al., 2018). Indeed, S. brasiliensis is frequently used as a monitor for TBT in the Brazilian coast (Otegui et al., 2019). ...
Imposex is is a well-documented deleterious effect caused by tributyltin (TBT) in females of hundreds of Caenogastropoda species and it is a well-established way of predicting BTs occurrence in marine systems. This study presents the very first information on the presence and distribution of imposex in Stramonita brasiliensis (Claremont and Reid, 2011) in the Brazilian Legal Amazon, within a Ramsar site, during a 6-year appraisal after the TBT global ban in 2008 (2012–2017). Imposex was evidenced in six out of the seven sampling sites, with 39.7% of the total affected females, most of them showing VDSI <1. The temporal appraisal allowed the identification of the introduction of new sources of TBT in some sites, as well as populational recovery in other sampling points. In addition, the dilution effect present in São Marcos Bay was also likely to play an important role in the imposex distribution.
... Krug & Zimmer (2004) and Young et al. (2012) also provided arguments against the hypothesis of frequent larval exchange across the Atlantic. Several supposedly amphi-atlantic gastropods from tropical shallow waters have been proved to be constituted of different species (e.g., Malaquias & Reid 2009;Claremont et al. 2011;Carmona et al. 2014), whereas others indeed show broad ranges (e.g., Claremont et al. 2011;Padula et al. 2016). ...
... Krug & Zimmer (2004) and Young et al. (2012) also provided arguments against the hypothesis of frequent larval exchange across the Atlantic. Several supposedly amphi-atlantic gastropods from tropical shallow waters have been proved to be constituted of different species (e.g., Malaquias & Reid 2009;Claremont et al. 2011;Carmona et al. 2014), whereas others indeed show broad ranges (e.g., Claremont et al. 2011;Padula et al. 2016). ...
The present study aims to fulfill the gap of taxonomic knowledge on Triphoridae from Brazil. We describe five new species (Isotriphora uncia sp. nov., Isotriphora leo sp. nov., Monophorus verecundus sp. nov., Sagenotriphora albocaput sp. nov., Similiphora lucida sp. nov.), report five species previously known only from the Caribbean and related areas (Cheirodonta dupliniana (Olsson, 1916), Eutriphora auffenbergi Rolán & Lee, 2008, Isotriphora tricingulata Rolán & Fernández-Garcés, 2015, Marshallora ostenta Rolán & Fernández-Garcés, 2008, Monophorus caracca (Dall, 1927) comb. nov.) and describe six morphotypes at the generic level (Isotriphora sp. 1, Marshallora sp. 1, Nanaphora sp. 1, Sagenotriphora sp. 1, Sagenotriphora sp. 2, Similiphora sp. 1). Remarks are made to some species previously recorded from Brazil, including the invalidation of records, problems of generic allocation and geographical range extensions. Maps of the geographical distribution are provided for the 65 currently recognized species of Triphoridae from Brazil. Of these, 31 species are endemic to Brazil and 58 inhabit the continental shelf vs only seven from the continental slope. A distinct geographical zone occurs in southeastern Brazil. A few species occur exclusively near the mouth of the Amazon River, whereas others inhabit a local biogenic reef, possibly serving as a biogeographical corridor that connects western Atlantic populations. Species of Isotriphora from Brazil are particularly common around oceanic islands, probably due to adopting intracapsular metamorphosis, which may have evolved in more than one evolutionary event.
... In northern South America, there is a 2300-km area under the influence of the OAB freshwater discharge ( Fig. 5a; Briggs 1995;Floeter et al. 2008;Reid 2009;Claremont et al. 2011), where A. scabra is absent (Fig. 1), suggesting a historic isolation between CS and SWA. However, the SWAþCS group indicates, at least, a recent genetic connectivity between CS and SWA regions, as does the CS sole lineage split from the SWAþCS during the Pleistocene (,1 million years ago). ...
... The contemporaneous oceanographic circulation in the GMx was established later, after the Panama seaway closure (9.2 million to 3.2 million years ago; Muss et al. 2001;O'Dea et al. 2016). Because our molecular clock suggested Pleistocene WGM differentiation, more recent oceanographic changes are likely to have influenced A. scabra genetic discontinuity (Harrison 2004;Claremont et al. 2011) rather than the GMx ancient formation (Pindell 1993;Pindell and Kennan 2009). In this regard, the intensification of the Gulf Stream (Haug and Tiedemann 1998;Wunsch 2003;Schneider and Schmittner 2006), an extension of the Loop Current of GMx , during the Panama Isthmus closure (9.2 million to 3.2 million years ago; O'Dea et al. 2016), and Quaternary sea-level fluctuations (the past 2.4 million years; Hewitt 2004) might have created or strengthened GMx isolation. ...
Species with biological traits favourable to long-distance marine larval dispersal might show a phylogeographic structuring over broad regions, even when they are genetically connected within smaller scales. Here, we evaluated this hypothesis by using the widespread amphidromous shrimp Atya scabra, predicting a genetic discontinuity across biogeographical barriers throughout the Western Gulf of Mexico (WGM), Caribbean Sea (CS), south-western Atlantic (SWA) and eastern Atlantic (EA). Using cytochrome oxidase subunit 1 (COI) and 16S ribosomal unit (16S) gene fragments, we did a phylogeographic assessment and genetic characterisation with Bayesian clustering, AMOVA, haplotype networks and demographic analyses. As predicted, three discrete genetic groups, corresponding to the regions WGM, CS and EA, were uncovered by COI, as well an unpredicted SWA+CS group. The 16S fragment detected a low genetic variation, probably owing to a recent lineage differentiation, which was estimated by the COI molecular clock. We evaluated the role of the biological traits of A. scabra, as well as the consequences of Panama Isthmus closure and Pleistocene glaciation cycles in the lineage isolation of WGM and EA, as well as the genetic connectivity shown within regions and between CS and SWA. Our results highlighted that amphidromous species genetically connected over large scales should be genetically characterised in their wide distribution to provide more comprehensive systematics and to assist decision-making in biological conservation.
... Cependant cette approche taxonomique traditionnelle a montré ses limites, et les études les plus récentes sur les mollusques marins sont basées sur une approche intégrative combinant des données moléculaires et traditionnelles (Puillandre et al. 2009, Claremont et al. 2011, Zou et al 2012. Cette étude montre donc que le groupe de Buccinum dorbignyi comprend au moins sept espèces; cette diversité cryptique est comparable à celle observée par Mediterranean Aplus show a remarkable morphological variation that is congruent with their mode of development. ...
... Historically, shelled gastropods taxonomy has been almost entirely based on shell characters, which are still commonly used even though morphological variation caused by adaptation to environmental pressures has been documented (Vermeij 2006). An exclusively traditional morphological taxonomy has shown its limits, and the most recent studies on marine molluscs have integrated molecular and traditional approaches to resolve taxonomic questions (e.g.: Puillandre et al. 2009, Claremont et al. 2011, Zou et al. 2012. ...
L’originalité du golfe de Gabès (Sud de la Tunisie) a été reconnue par les malacologistes depuis le19ème siècle mais reste mal définie. Les espèces de cette région présentent des caractères morphologiques qui ont conduit à l’établissement de variétés, sous-espèces et espèces faiblement caractérisées. Certains auteurs les traitent comme des taxons endémiques tandis que d'autres les considèrent comme de simples variants locaux d'espèces à large répartition méditerranéenne. Le manque d’information concernant la valeur taxonomique de ces caractères morphologiques ne permet pas de traiter de façon robuste la question de l’endémisme dans le golfe de Gabès. Le premier objectif est de réviser le statut taxonomique des mollusques du golfe de Gabès en s’appuyant sur une approche de taxonomie moléculaire. La confrontation des différents caractères a permis d’identifier ceux qui discriminent correctement les individus en espèces, d’éliminer à l’inverse ceux qui ne remplissent pas cette fonction et d’en redéfinir de nouveaux. Le deuxième objectif est de relier les particularités faunistiques du Golfe à ses caractéristiques océanographiques et de discuter les phénomènes de spéciation qui pourraient être à l’origine de l’endémisme. Nos analyses ont porté sur six genres: Jujubinus (Trochidae), Diodora (Fissurellidae), Ocinebrina, Muricopsis (Muricidae), Aplus (Buccinidae) et Tritia (Nassariidae). L’approche intégrative utilisée a permis de proposer des hypothèses de délimitation d’espèces que nous avons ensuite confrontées aux données morphologiques et géographiques. Au final, l’endémisme est confirmé dans certains cas mais l’hypothèse qu’une partie des espèces décrites du golfe de Gabès ne sont que des variétés éco phénotypiques est également attestée. Notre approche moléculaire a mis aussi en évidence l’existencede nouvelles espèces et d’espèces cryptiques insoupçonnées dans la Méditerranée. Finalement l’hypothèse que le golfe de Gabès est un centre de spéciation est retenue. Plus de données moléculaires (reliées à des données fossiles) d’autres groupes provenant de différentes localités (spécialement du golfe de Syrte) apparaissent toutefois nécessaires.
... Decades of research on genital deformities in gonochoristic gastropods have revealed a strong cause-effect relationship between the occurrence of imposex and the presence of organotin compounds such as tributyltin (TBT) and, in some cases, triphenyltin (TPT) in the aquatic system (Smith, 1981;Gibbs et al., 1987;Stroben et al., 1992;Smith, 1996). More than 260 gastropod species are affected by imposex (Sternberg et al., 2010;Titley-O'Nea et al., 2011), among which 76 species belong to the family of Muricidae (Shi et al., 2005), including the geographically widespread Stramonita haemastoma (Limaverde et al., 2007;Claremont et al., 2011;Toste et al., 2013;El Ayari et al., 2015). Since 2005 the known number of affected species has increased considerably to include Thais deltoidea (Costa et al., 2008), Pugilina morio (de Azevedo et al., 2012), Heleobia australis (Neves et al., 2013), Nassarius mutabilis (Lahbib et al., 2013), Xanthochorus buxea (Guabloche et al., 2013), Gemophos viverratus (Lopes-dos-Santos et al., 2014), Babylonia spirata (Afsar et al., 2015), Plicopurpura pansa (Domínguez-Ojeda et al., 2015), Olivella minuta, Hastula cinerea (Petracco et al., 2015) and Oliva peruviana (Batista et al., 2016). ...
... Despite the abundance of S. haemastoma in the Mediterranean and Atlantic Ocean (Harding and Harasewych, 2007;Claremont et al., 2011), information about the status of pollution by organotin compounds is still limited geographically. Few studies have been conducted in the Eastern Mediterranean basin (Rilov et al., 2000;Rilov et al., 2001), or the Atlantic Coast (Spence et al., 1990;El Mortaji et al., 2011), in contrast, studies in Western Mediterranean basin have been much more abundant (Chiavarini et al., 2003;Lemghich and Benajiba, 2007;El Mortaji et al., 2011;Boulajfene et al., 2015;El Ayari et al., 2015). ...
The development of male genital tract by female gastropods, or imposex, can be caused by the tributyltin used in antifouling paints. A spatial survey of imposex in the gastropod Stramonita haemastoma was conducted across five Western Mediterranean and eleven North-Eastern Atlantic sites, in order to monitor the effectiveness of the
tributyltin regulation imposed in the International Maritime Organisation. Imposex still occurs in eight out of
eleven Mediterranean sites and in three out of five Atlantic sites. Extreme values of imposex incidence (I%) and degree (VDSI) were recorded in Tunisia, mainly in Bizerta channel (I% = 96.2%, VDSI = 0.96). However, the
Relative Penis Length index (RPLI) was higher in Western Mediterranean sites where values varied between 0.56 in Algiers (Algeria) and 11.80 in Bouznika (Morocco). In the European sites, moderate to low imposex level and degree were recorded. All the affected sites were below the Ecotoxicological Assessment Criteria (EAC) derived for TBT.
... A similar study documented the division of species of a related genus, Stramonita Schumacher, 1817, which occurs only in fully marine, stenohaline habitats. That study described the Brazilian population previously known as S. haemastoma Linné, 1767 as S. brasiliensis Claremont & Reid, 2011(Claremont et al. 2011. ...
... A similar study documented the division of species of a related genus, Stramonita Schumacher, 1817, which occurs only in fully marine, stenohaline habitats. That study described the Brazilian population previously known as S. haemastoma Linné, 1767 as S. brasiliensis Claremont & Reid, 2011(Claremont et al. 2011. ...
Thaisella guatemalteca is a new species with type locality in Puerto Barrios, Department of Izabal, Caribbean (Atlantic) coast of Guatemala. Its anatomical attributes are described. The main intention is to provide data for a future re-evaluation of a possible complex of species that inhabit different estuarine regions along the Western Atlantic, of which this species is part. The new species can be easily distinguished by its small size, well-developed anal canal, simple sculpture, stubby periumbilical keel, and an orange aperture bearing poorly developed riblets. Anatomically, the set of distinctive features include an anal flap at the mantle edge, elongated radular teeth, strong asymmetry of salivary glands, a lack of accessory salivary glands, a pair of gastric ducts to the digestive gland, a relatively small and simple penis, and a pallial oviduct lacking a bursa and other chambers. The significance of these findings is still obscure because these characters are unknown in allied species, but provisionally, the genus Thaisella appears to be exclusively American (mostly Atlantic), always associated with an estuarine environment, and possessing geographically restricted species. © E. Schweizerbart'sche Verlagsbuchhandlung (Nägele u. Obermiller) and Senckenberg Gesellschaft für Naturforschung, 2017.
... Understanding Drupella snail reproduction, recruitment, and early life history is essential to monitor and manage their outbreaks. Sexual maturity occurs around 2.5 years, with an expected lifespan of 7-8 years (Turner, 1994;Ismail et al., 2000;Claremont et al., 2011b). Drupella snails start as veliger larvae, then metamorphose into crawling juveniles (Holborn et al., 1994). ...
The recurring outbreaks of Drupella snails are a significant threat to coral reef ecosystems on a global scale. However, research on Drupella snails is currently very fragmentary. This article explores the ecological impacts and mitigation methods of Drupella snails and its outbreaks, and draws the following main conclusions. 1) Drupella snails inhabit the tropical oceans of the Indo-Pacific, utilizing their specialized radula to feed on coral polyps, and they predominantly spawn during summer, attaching egg capsules onto coral skeletons. 2) An outbreak of Drupella snails is defined by a density of > 2 ind/m², but large aggregations alone do not necessarily indicate an outbreak. 3) The damage of coral reef ecosystem is the primary cause of Drupella snail outbreaks, with the hypotheses of “terrestrial nutrient input” and “overfishing of predator” being widely accepted but not fully explaining all outbreak events. 4) Countering Drupella snail outbreaks involves improving the health of coral reef ecosystems, protected areas, biological control and manual removal, though manual removal is the most direct and effective in short-term. 5) The understanding of the physiological and ecological characteristics of Drupella snails is inadequate at present, with larval development and population ecology being areas of particular under-investigation. 6) Studies of Drupella snail outbreaks have focused mainly on mid-outbreak stages, with little attention to early warnings beforehand or adverse outcomes afterwards. Despite significant challenges, addressing knowledge gaps in the biology of Drupella snails is crucial to determine the true causes of their outbreaks and identify corresponding solutions.
... Genetically, all Hypselodoris species from the Atlantic Ocean have been assigned to the genus Felimare (Johnson & Gosliner 2012). Conversely, species located along the Atlantic Ocean's east and west coastlines are referred to as amphi-Atlantic species (Malaquias & Reid 2009;Claremont et al. 2011). ...
Biodiversity in the Mediterranean Sea has not yet been fully explored. There has been very little research on molluscs along the Libyan coast. An individual of the chromodoridid nudibranch Felimare picta (Philippi, 1836) was encountered during scuba diving at the Lido resort near the Tobruk baybasin. The sample was carefully transported to the lab in seawater, photographed, and identified. The current study revealed that Felimare picta was recorded for the first time on the Libyan coast. Despite Felimare picta being rather common in many Mediterranean regions, records of it on the southern Mediterranean coasts are extremely rare or absent.It may be concluded that this study represents not only the southernmost record of Felimare picta in the Mediterranean but also the first record of the species in Libya.
... Yet, our results suggested that this lineage comprises a species complex, as mitochondrial divergence between specimens ranged from 7 to 15% but differences were negligible at the nuclear level. Species complexes are common among gastropods and have lately been the focus of integrative taxonomic approaches, as is the case of Ocinebrina aciculata (Lamarck, 1822), Talisman scrobilator (Linnaeus, 1758), Stramonita haemastoma (Linnaeus, 1767), Dendropoma petraeum (Monterosato, 1884), to name a few (Calvo et al., 2009(Calvo et al., , 2015Claremont et al., 2011;Barco et al., 2018;Smriglio et al., 2019;Crocetta et al., 2020). The high levels of divergence in the cox1 among localities within the Alboran Sea (Malaga, Benidorm, and Alboran Island) were striking. ...
Despite a long history of taxonomic studies on the genus Tricolia Risso, 1826, there is a shortfall on thorough systematic molecular reviews of the taxon from the NE Atlantic and Mediterranean coasts. Aiming to assess the genetic distinctness among morphospecies and the taxonomic status of currently accepted large sized species in these areas, we conducted a molecular phylogenetic analysis of the genus based on one mitochondrial (cox1) and two nuclear (28S and ITS2) markers. Seven Tricolia species were consistently retrieved in the analyses, including a new genetic lineage in the NE Atlantic designated as Tricolia sp. 1. Molecular analyses revealed that only one species, T. azorica, occurs in the NE Atlantic archipelagos. The sister taxa T. pullus (Mediterranean) and T. picta (NE Atlantic) should be classified as distinct species, instead of subspecies of the T. pullus group (sensu Gofas 1982). Tricolia miniata is also a complex of species in the Mediterranean and future studies across the distribution range are necessary to clarify its status.
... The influence of ocean currents on species formation and population genetic structure differentiation of marine organisms has long been confirmed [62]. Marine plankton have high passive dispersal ability, which can spread along the direction of ocean currents during the planktonic period, thus promoting genetic exchange between different populations [63][64][65]. The East China Sea is the main producing area of M. unguiculatus in China, and its mass breeding season is in winter every year. ...
Simple Summary
Microsatellite markers are widely used in genetic breeding and population genetic structure analysis. In this study, microsatellite markers are used to analyze the genetic diversity and population genetic structure of Mytilus unguiculatus in seven coastal areas of China. The results showed that M. unguiculatus has high genetic diversity with genetic structure differences observed between the Qingdao population and the other six populations. The genetic structure of M. unguiculatu is relatively weak. These findings provide a molecular biological basis for the rational development and protection of wild germplasm resources of Mytilus unguiculatus in China and can serve as a data reference for the formulation of reasonable breeding programs.
Abstract
The hard-shelled mussel Mytilus unguiculatus plays an important role in mussel aquaculture in China due to its characteristic and nutritive value. In this study, 10 microsatellite loci are used to study the genetic diversity and genetic structure of seven location populations of M. unguiculatus in coastal areas of China. The results of amplification and genotyping show that the observed heterozygosity (Ho) and the expected heterozygosity (He) are 0.61~0.71 and 0.72~0.83, respectively. M. unguiculatus has high genetic diversity. The inbreeding index (FIS) of M. unguiculatus is significantly positive (FIS: 0.14~0.19), indicating that inbreeding might exist within populations. The genetic structure of M. unguiculatus is weak within populations from the East China Sea All results showed that genetic differences existed between the Qingdao population from the Yellow Sea and other populations from the East China Sea. It does not detect a population bottleneck event or expansion event in the populations. The results from this study can be used to provide important insights in genetic management units and sustainable utilization of M. unguiculatus resources and provide a better understand of genetic structure of marine bivalve with similar planktonic larval stage in the China Sea.
... In contrast, environmental/ecological isolation necessarily implicates divergent selection related to abiotic or biotic factors as the principal factor limiting gene flow and promoting genomic differentiation within species. Isolation by environment (Wang & Bradburd, 2014;Wang & Summers, 2010) and isolation by ecology (Claremont et al., 2011;Shafer & Wolf, 2013), which we collectively refer to as "IBE", describe patterns in which genetic distance among individuals or populations positively correlates with environmental or ecological differences, independent of geographic isolation. ...
Diverse geographic, environmental, and ecological factors affect gene flow and adaptive genomic variation within species. With recent advances in landscape ecological modelling and high‐throughput DNA sequencing it is now possible to effectively quantify and partition their relative contributions. Here we use landscape genomics to identify determinants of genomic differentiation in the forest tent caterpillar, Malacosoma disstria, a widespread and irruptive pest of numerous deciduous tree species in North America. We collected larvae from multiple populations across eastern Canada, where the species experiences a diversity of environmental gradients and feeds on a number of different host tree species, including trembling aspen (Populus tremuloides), sugar maple (Acer saccharum), red oak (Quercus rubra), and white birch (Betula papyrifera). Using a combination of reciprocal causal modelling (RCM) and distance‐based redundancy analyses (dbRDA), we show that differentiation of thousands of genome‐wide single nucleotide polymorphisms (SNPs) among individuals is best explained by a combination of isolation by distance, isolation by environment (differences in summer temperatures and length of the growing season), and differences in host association. Configuration of suitable habitat inferred from ecological niche models was not significantly related to genomic differentiation, suggesting that M. disstria dispersal is agnostic with respect to habitat quality. Although population structure was not discretely related to host association, our modelling framework provides the first molecular evidence of host‐associated differentiation in M. disstria, congruent with previous documentation of reduced growth and survival of larvae moved between natal host species. We conclude that ecologically‐mediated selection is contributing to variation within M. disstria, and that divergent adaptation related to both environmental conditions and host association should be considered in ongoing research and management of this important forest pest.
... In fact, top predators, such as S. brasiliensis, are susceptible to biomagnification processes exhibiting measurable biological alterations (e.g., imposex) which have been historically used to monitor coastal contamination by tributyltin (Castro et al., 2012;Rossato et al., 2016). In addition, S. brasiliensis is widely distributed an abundant on rocky shore substrates, between Colombia and Uruguay (Claremont et al., 2011;Veiga et al., 2015), fulfilling relevant requirements for an ideal bioindicator. ...
Morphological, structural and compositional alterations in shells of molluscs have been proposed as putative biomarkers of chemical contamination in coastal zones. Despite this, few studies were carried out using top predator gastropods which tend to be more susceptible to contamination exposure. Thus, the present study assessed disturbances on shells of Stramonita brasiliensis considering compression resistance and organic and mineralogical matrix composition, related to morphometric alterations. Results showed reductions in compression resistance and organic matrix content associated with higher contaminated sites. In addition, a predominance of calcite polymorphs was seen in shells obtained in polluted areas. Such outputs were consistent with local contamination levels which may have induced the observed alterations. Thus, changes in mollusc shells showed good performance as potential biomarkers of coastal contamination, being probably observed in other species of carnivorous gastropods around the world.
... Overall, such conditions may impact on gene flow by subtracting larvae from coastal waters and exposing them to more oceanic, possibly unfavorable, con- ditions. Pelagic larval duration and pattern of oceanic currents proved very important in shaping geographic patterns of genetic variation in mollusks(Claremont, Williams, Barraclough, & Reid, 2011;Selkoe & Toonen, 2011). ...
Wild populations of the pustulose ark, Anadara tuberculosa (Bivalvia), an emblematic species of the East Pacific mangrove ecosystem declined in South American countries (Colombia, Ecuador, and Peru) mainly due to overharvesting and habitat loss or degradation. Understanding the genetic aspects of geographic variations and population structure of A. tuberculosa, currently unknown, appears as a priority to fishery authorities in order to elaborate integrated and collaborative conservation policies for fishery management, aquaculture, and stock enhancement programs. We used mtDNA sequence data to investigate haplotype diversity, genetic structure, and demography of A. tuberculosa. Results indicate genetic homogeneity of populations distributed north and south of the equator, respectively. However, statistically significant differentiation emerged between northern and southern populations with pairwise фST values ranging between 0.036 and 0.092. The oceanic current system acting in the area (Panama Current and Humboldt Current) might play a role in limiting the larval dispersal of the species, still poorly understood. Demography reconstruction supported recent population expansion, possibly started after last glacial maximum. Our results would suggest separate and independent management of populations north and south of the equator. Wild populations of the pustulose ark, an emblematic species of the East Pacific mangrove ecosystem, declined in South American countries. We used mtDNA sequence data to investigate haplotype diversity, genetic structure, and demography of this species north and south of the equator. Results supported recent population expansion after last glacial maximum and suggest separate management.
... The distance that larvae can disperse may also be affected by the size of the habitat gap itself, as well as north to south longshore currents and low salinity plumes from the rivers Loire and Gironde. For example, the larvae of Stramonita haemastoma (Linnaeus, 1767) are capable of long distance dispersal (Claremont et al., 2011). It was first recorded just south of the habitat gap in St ...
In biogeography, patterns of species abundance, distribution, size, population genetics and morphology often do not follow simple latitudinal gradients – which are classically assumed in such “rules” as the abundant centre hypothesis and Bergmann’s rule. Rather, the biogeography of a species or groups of species are more likely to be associated with abiotic and biotic variables such as availability of suitable habitat, temperature, dispersal potential, and habitat specificity. However, previous biogeographic studies rarely go beyond simple pattern description, particularly for marine species. In this thesis, I find that regional patterns of abundance, distribution, size, morphology, and population genetics are often associated with regional and local differences in environmental and biotic variables, such as upwelling intensity, habitat availability, and intrinsic attributes of species ecology, such as their level of habitat specificity. For example, a lower availability of suitable habitat can result in a fragmented distribution and subsequently lower genetic connectivity for species dependent upon that habitat. Differing abundances and recruitment among localities may also affect intraspecific competition, so density-dependent interactions occur, resulting in smaller/larger individuals. This would not necessarily follow the classically assumed temperature-size rule of smaller individuals usually being found at higher temperatures. Within a species, differing growth rates and adaptations to environmental variables can result in local morphological variation.
These biogeographic concepts are explored in depth using rocky intertidal species of the Bay of Biscay as a model system, which contains a 230 km habitat gap and regional variation in temperature unrelated to a latitudinal gradient. In Chapter 2, the almost complete mitochondrial genome of Steromphala umbilicalis is described in relation to other Vetigastropoda. By removing different genes, and using amino acid or nucleotide sequences, different phylogenies are generated. From this, it is proposed that selection mechanisms may be occurring. In Chapter 3, the population genetics of the congeners S. umbilicalis (habitat generalist) and S. pennanti (habitat specialist), are described over the sympatric portion of their range, using both a newly developed mitochondrial marker and microsatellites. By combining this information with abundance estimates, S. umbilicalis is shown to have a more continuous distribution and is more abundant, and therefore shows greater genetic connectivity than S. pennanti which has a more fragmented distribution and lower abundance. In Chapter 4, the abundances, size structures and distributions of S. umbilicalis, S. pennanti, Phorcus lineatus, Patella vulgata and Patella depressa are explored using multiple linear regression for environmental variables including sea surface temperature, air temperature, wave exposure, distance to the habitat gap, and adjacent rocky substrate. Sea temperature showed a positive relationship with P. depressa abundance and the opposite for P. vulgata. Subsequent density-dependent interactions in P. depressa resulted in smaller individuals being associated with higher abundance between localities, and between quadrats within localities for both Patella species. The habitat gap amplified the differences in abundance between the cool water region in northern France dominated by P. vulgata and the warm water Basque region dominated by P. depressa. In Chapter 5, the aspect ratio of S. umbilicalis is explored at the macroscale in relation to multiple environmental variables. Sea temperature shows the best relationship with aspect ratio, both with initial European data and an expanded dataset including museum specimens from the British Isles. Whilst the underlying mechanism is unclear, it may be linked to a decreased growth rate at higher temperature, resulting in a more pointed shell.
This work throws new light on biogeographic patterns and processes, particularly regarding temperature around range centres. It has implications when considering the impacts of global warming, particularly in relation to rocky intertidal biogeography.<br/
... These results suggest high levels of gene flow between populations but there may often be limits to the actual dispersal of marine species with high dispersal potential (Scheltema 1986;Hellberg 2009). These limits are probably related to complicated marine environments such as ocean currents and gyres, bays and islands, water temperature and salinity, habitat discontinuity, and even anthropogenic activities (De Woody and Avise 2000; Rose et al. 2006;Yasuda et al. 2009;Claremont et al. 2011;Haye et al. 2014;Ellis et al. 2017). All of the above factors could create invisible barriers to gene flow in some directions or at some times. ...
Ostracods (Crustacea, Ostracoda) are small bivalved crustaceans, contributing to the marine zooplankton community. They are widely distributed and are relatively abundant components of the marine mesozooplankton worldwide, playing an important role in the transport of organic matter to deep layers. By analysing the mitochondrial COI gene, we explored the population genetic structure and haplotype pattern of Porroecia spinirostris which is the dominant ostracod in the South China Sea. We investigated the population genetic structure of ostracods at medium spatial scales in the absence of physical barriers. Our data provides evidence of the importance of both long-distance dispersal as well as genetic isolation in determining the seascape genetic structure of this species. Our data suggest that P.spinirostris can achieve long distance dispersal and specific haplotypes were successful in colonizing habitats from the Xisha to the Nansha area. A total of 36 haplotypes were defined from 85 individuals with most of these haplotypes occurring only once. The dominant haplotype was found in twelve sampling sites. The largest distance between two sampling sites harbouring this haplotype is more than 700 km. Our findings of long distance dispersal in the South China Sea combined with mild genetic differentiation among fifteen sampling sites (average ΦST = 0.167) are in line with a scenario where population genetic structure is strongly impacted by colonization patterns. The seascape genetic structure of P.spinirostris in the South China Sea reflects both the importance of long distance dispersal as well as of reduced levels of gene flow, likely caused by colonization events followed by demographic expansions.
... All containers were labeled with standard collection data and registered in the malacological collection of the Laboratório de Ecologia Aplicada e Bioinvasões da Universidade Federal do Paraná (LEB-IO 511-542), Pontal do Paraná, Brazil. Taxonomic identification was based on specialized literature (Matthews & Coelho 1972;Diaz & Puyana 1994;Guerón & Narchi 2000;Papp & Duarte 2001;Matthews-Cascon & Rabay 2003;Absalão & Pimenta 2005;Amaral et al. 2006;Denadai et al. 2006;Rios 2009;Rosenberg 2009;Claremont et al. 2011;Teso & Pastorino 2011;Rocha & Matthews-Cascon 2015). The same literature was also used to present herein brief descriptions, bathymetric data, and geographic distribution of the species collected. ...
Bycatch are organisms that are inadvertently caught during fishery. They are usually rejected and/or returned to the sea, and are killed in the process. The aim of this study is to characterize the Gastropoda and Bivalvia caught as bycatch of the trawling fisheries of the Atlantic seabob, Xiphopenaeus kroyeri, on the coast of Paraná state, southern Brazil. This work was carried out in the municipality of Pontal do Paraná. A total of 651 living individuals were collected, including four species belonging to three families of gastropods and six species distributed into four families of bivalves. Although the frequency of gastropods (96.5%) was much higher than that of bivalves (3.5%), species diversity was higher in bivalves. Among the Gastropoda, Olivancillaria urceus (Gmelin, 1791) was the most abundant species, with 611 individuals. Among the bivalves, Anadara brasiliana (Lamarck, 1819) had the most significant occurrence, with eight individuals. It is important to develop further studies to identify the potential impact of trawling on these mollusk populations and the creation and implementation of public policies and the adoption of technological devices to reduce the bycatch in order to preserve them.
... Although geographical speciation on small spatial scales has been inferred in some tropical marine fishes and gastropods (Meyer et al., 2005;Tornabene et al., 2015;Worheide, Epp, & Macis, 2008), allopatric speciation in most marine animals occurs in response to barriers operating at much larger geographical scales, spanning large ocean regions or even different ocean basins (Ahti et al., 2016;Claremont, Williams, Barraclough, & Reid, 2011;Frey, 2010;Waldrop et al., 2016). ...
Aim
Biogeographical processes underlying Indo‐Pacific biodiversity patterns have been relatively well studied in marine shallow water invertebrates and fishes, but have been explored much less extensively in seaweeds, despite these organisms often displaying markedly different patterns. Using the marine red alga Portieria as a model, we aim to gain understanding of the evolutionary processes generating seaweed biogeographical patterns. Our results will be evaluated and compared with known patterns and processes in animals.
Location
Indo‐Pacific marine region.
Methods
Species diversity estimates were inferred using DNA‐based species delimitation methods. Historical biogeographical patterns were inferred based on a six‐gene time‐calibrated phylogeny, distribution data of 802 specimens, and probabilistic modelling of geographical range evolution. The importance of geographical isolation for speciation was further evaluated by population genetic analyses at the intraspecific level.
Results
We delimited 92 candidate species, most with restricted distributions, suggesting low dispersal capacity. Highest species diversity was found in the Indo‐Malay Archipelago (IMA). Our phylogeny indicates that Portieria originated during the late Cretaceous in the area that is now the Central Indo‐Pacific. The biogeographical history of Portieria includes repeated dispersal events to peripheral regions, followed by long‐term persistence and diversification of lineages within those regions, and limited dispersal back to the IMA.
Main conclusions
Our results suggest that the long geological history of the IMA played an important role in shaping Portieria diversity. High species richness in the IMA resulted from a combination of speciation at small spatial scales, possibly as a result of increased regional habitat diversity from the Eocene onwards, and species accumulation via dispersal and/or island integration through tectonic movement. Our results are consistent with the biodiversity feedback model, in which biodiversity hotspots act as both “centres of origin” and “centres of accumulation,” and corroborate previous findings for invertebrates and fish that there is no single unifying model explaining the biological diversity within the IMA.
... Malaquias & Reid 2008;Rosenberg 2009;Claremont et al. 2011;Abbate & Simone 2015). Malacological material obtained during the collection was deposited in the collections of the Museu de História Natural Capão da Imbuia (MHNCI 5208-5297), Curitiba, Brazil, and Museu de Zoologia da Universidade de São Paulo (MZUSP 121844-121845), São Paulo, Brazil. ...
p style="text-align: justify;">A Ilha do Farol é uma ilha continental, no estado do Paraná, sul do Brasil. Devido à sua posição em relação ao continente, três ambientes distintos são observados nela: área de costão rochoso exposto ao mar aberto (A); área estuarina (B); área de praia arenosa (C). Considerando que as ilhas continentais são excelentes modelos de estudo que reproduzem as condições ambientais da zona costeira em menor escala, o estudo teve como objetivo levantar e pesquisar a malacofauna marinha na Ilha do Farol e comparar sua diversidade e composição. O método de amostragem foi baseado em coletas mensais nos três ambientes da ilha durante dois anos (2011-2012). O levantamento encontrou 91 espécies: 47 Gastropoda, 41 Bivalvia e três Scaphopoda. A maior riqueza e abundância de espécies prevaleceu no ambiente A. A maior equidade foi observada em B e o maior domínio em C. Houve predominância de Gastropoda e Bivalvia em A, enquanto a frequência de Scaphopoda não variou entre os ambientes. A composição de espécies das três classes variou entre as três áreas. A variação da diversidade e composição das espécies nos três ambientes podem estar relacionados com as características naturais de cada ambiente da ilha, como salinidade e ação de ondas.
Palavras chave : Abundância, conservação, equitabililidade, levantamento, riqueza, Mollusca.
Abstract : Farol Island is a continental island in the state of Paraná, southern Brazil. Due to its position in relation to the continent, three distinct environmental areas are observed: rocky shore area with open exposure to the sea (A) estuarine area (B); sandy beach area (C). Considering that the continental islands are excellent study models that reproduce the environmental conditions of the coastal zone in a smaller scale, the study aimed at surveying and researching the marine malacofauna on the Farol Island and comparing the diversity and shellfish composition. The sampling method was based on a monthly collection in three locations for two years (2011-2012). The survey found 91 species: 47 Gastropoda, 41 Bivalvia and three Scaphopoda. The highest abundance and species richness prevailed in environmental area A. The greatest equitability was observed in B and the highest dominance in C. There was a predominance of Gastropoda and Bivalvia in A, while the frequency of Scaphopoda did not vary among environments. The species composition of the three classes varied among the three areas. The variation of diversity and species composition in the three environments may be related to the natural characteristics of each side of the island, as salinity and wave action.
Key words : Abundance, conservation, equitability, survey, richness, Mollusca.</p
... The Stramonita species complex is known to tropical latitudes of the Atlantic and eastern Pacific Oceans and, in Brazil, it was represented by the species Stramonita haemastoma, Stramonita floridana and Stramonita rustica. Claremont et al. (2011) working on molecular phylogeny of Stramonita and also using known distribution and morphological data (shell shape and number of crenulations) concluded that this muricid genus is monophyletic, restricted to the tropical and warm-temperate Atlantic and eastern Pacific (its speciation has occurred only within the Atlantic, despite its long pelagic larval duration); S. haemastoma is amphi-Atlantic but only found in Africa and Venezuela; S. floridana only found in the Mexico Gulf; and its Brazilian representants are S. rustica and the new species S. brasiliensis. ...
Through controlled exposure to tributyltin (TBT), the effects of season, size, and population origin were evaluated on imposex incidence in Stramonita brasiliensis. Four experiments were carried out with organisms collected from three different sites on the Brazilian coast (Torres - Rio Grande do Sul, Farol de Santa Marta - Santa Catarina, and Aracruz - Espírito Santo). S. brasiliensis were anesthetized, sexed, measured, classified by size in small (< 30 mm), medium (≥ 30 to ≤ 40 mm), or big (> 40 mm) and injected in the foot muscle with 0.5 μg g-1 of TBT. Organisms were maintained during one month in aquariums with clear marine water under controlled laboratory conditions. One month after injection, the imposex assessments showed that the population from the southeast (tropical) region was more sensitive to TBT than the population from the south of Brazil (the temperate region). A greater sensitivity in the small and medium categories was observed. Females were also more susceptible to TBT when exposed during their reproductive period. Thus, the present study highlighted the need to ensure that intrinsic biological factors related to organisms are considered in such biomonitoring studies to avoid misinterpretation of results.
... These genetic divergences can be facilitated by the presence of dispersal barriers such as oceanic currents and/ or by the limitation of suitable habitats. Using comprehensive phylogenetic analyses, we evaluate how such dispersal barriers shape genetic divergence and speciation in the a geographically fragmented species complex (Lee and Foighil 2005;Meyer et al. 2005;Claremont et al. 2011). This is because genetic diversification seems to be affected by not only dispersal ability but also dispersal barriers. ...
Marine organisms with a planktonic larval stage can passively disperse long distance and are thus expected to have a wider distribution range and lower geographic variation. However, recent molecular phylogenetic studies have revealed that they often display a clear geographic genetic structure or even form a geographically fragmented species complex. These genetic divergences can be facilitated by the presence of dispersal barriers such as oceanic currents and/or by the limitation of suitable habitats. Using comprehensive phylogenetic analyses, we evaluate how such dispersal barriers shape genetic divergence and speciation in the intertidal snail genus Monodonta. Our phylogenetic analysis revealed various patterns of cladogenesis in Monodonta in East Asia. Genetic segregation between the Japanese and Ryukyu Archipelagos are detected in M. labio and M. perplexa perplexa. However, the relationship of geographical border and lineages does not correspond to those two because they show different habitat preference. M. labio distributed in the Japanese mainland is separated by the boundary corresponding to the point from which oceanic currents split into different directions. In contrast, species inhabiting various environments such as M. confusa are not genetically separated in Japan. In the peripheral oceanic Ogasawara Islands, two Monodonta species form each endemic lineage, although these two underwent different colonization processes to the islands. These findings suggest that the genus Monodonta has been genetically diversified around Japan, probably due to its correlations with dispersal ability, oceanic current, and habitat preferences. These factors may be effective causes for diversification of marine gastropods with a planktonic stage.
... Além das características ambientais, algumas necessidades biológicas e adaptações fisiológicas de cada espécie de gastrópode pode explicar a localização nos níveis do costão rochoso (BOADEN & SEED, 1985;RAFFAELI & HOWKINS, 2012). Dentre as espécies de gastrópodes que constituem a malacofauna da região na costa sul brasileira, podemos destacar as espécies Littorina flava, Littorina ziczac, Littorina lineolata, Stramonita brasiliensis, Fissurella clenchi e Lottia subrugosa (RIOS, 2009;CLAREMONT et al., 2011;ROSENBERG, 2015). Portanto, este trabalho teve como objetivo analisar a distribuição dos gastrópodes de um costão rochoso na desembocadura do Complexo Estuarino de Paranaguá e relacionar com os parâmetros ambientais. ...
O objetivo deste trabalho é caracterizar a distribuição dos gastrópodes na desembocadura do Complexo Estuarino de Paranaguá. Foram realizadas em um costão rochoso da Ilha do Mel oito coletas mensais, durante dois períodos (julho a outubro de 2010; janeiro a abril de 2011), em três níveis (Superior, Médio e Inferior), com três réplicas. Os parâmetros ambientais foram avaliados in situ (temperatura do ar, da água e salinidade). Observou-se a presença de Lottia subrugosa, Litorina flava, Litorina sp., Stramonita brasiliensis e Onchidella indolens. A distribuição dos gastrópodes foi caracterizada como tendo predominante L. subrugosa no nível Inferior, Litorina sp. no nível Médio e L. flava no nível Superior. Pode-se constatar que as espécies de gastrópodes de um costão rochoso na desembocadura do Complexo Estuarino de Paranaguá estão mais relacionadas com a capacidade de cada espécie em suportar dessecação, alimentação e agregações para reprodução do que as variáveis ambientais avaliadas.
... Marine organisms, on the other hand, are frequently broad cast spawners and therefore have high dispersal potentials, making allo patric speciation seem, at least at first glance, to be more challenging. However, not so obvious geographic barriers have been well documented for many marine groups, ranging from the size and temperature of ocean basins (Claremont et al. 2011) to water currents and substrates affecting larval settling (Cowen and Sponaugle 2099) to physical barriers on a small scale due to microhabitat preference (e.g., degree of wave energy on a rocky coastline; Claremont et al. 2012). The consensus view is that allo patric speciation is the norm in the ocean (Claremont et al. 2012), though some examples of sympatric divergence also exist (Krug 2011). ...
... Marine organisms, on the other hand, are frequently broad cast spawners and therefore have high dispersal potentials, making allo patric speciation seem, at least at first glance, to be more challenging. However, not so obvious geographic barriers have been well documented for many marine groups, ranging from the size and temperature of ocean basins (Claremont et al. 2011) to water currents and substrates affecting larval settling (Cowen and Sponaugle 2099) to physical barriers on a small scale due to microhabitat preference (e.g., degree of wave energy on a rocky coastline; Claremont et al. 2012). The consensus view is that allo patric speciation is the norm in the ocean (Claremont et al. 2012), though some examples of sympatric divergence also exist (Krug 2011). ...
... The large predatory gastropod (whelk) Stramonita haemastoma (Linnaeus, 1767) was considered a widely-spread species complex, but recent genetic analysis separated the complex to five different species 86 . The main distribution of the Mediterranean S. haemastoma includes, besides the whole Mediterranean, the Iberian coast, the west African coast down to Angola and the Macaronesian Islands (Azores and the Canaries), and a population also exists on the Venezuelan coast (Fig. 2d). ...
Even during the current biodiversity crisis, reports on population collapses of highly abundant, non-harvested marine species were rare until very recently. This is starting to change, especially at the warm edge of species' distributions where populations are more vulnerable to stress. The Levant basin is the southeastern edge of distribution of most Mediterranean species. Coastal water conditions are naturally extreme, and are fast warming, making it a potential hotspot for species collapses. Using multiple data sources, I found strong evidence for major, sustained, population collapses of two urchins, one large predatory gastropod and a reef-building gastropod. Furthermore, of 59 molluscan species once-described in the taxonomic literature as common on Levant reefs, 38 were not found in the present-day surveys, and there was a total domination of non-indigenous species in molluscan assemblages. Temperature trends indicate an exceptional warming of the coastal waters in the past three decades. Though speculative at this stage, the fast rise in SST may have helped pushing these invertebrates beyond their physiological tolerance limits leading to population collapses and possible extirpations. If so, these collapses may indicate the initiation of a multi-species range contraction at the Mediterranean southeastern edge that may spread westward with additional warming.
... An exclusively tra-ditional morphological taxonomy has shown its limits, and recent studies on marine molluscs have integrated molecular and traditional approaches to resolve taxonomic questions (e.g. Puillandre et al. 2009, Claremont et al. 2011, Zou et al. 2012. ...
Northeastern Atlantic and Mediterranean gastropods previously ascribed to the buccinid genus Pollia Gray, 1837 are more correctly classified in the genus Aplus de Gregorio, 1885. Using an integrative taxonomy approach combining molecular, morphological and geographic data, we revisit the limits of the extant species in the area, and propose a molecular phylogenetic hypothesis based on 66 specimens from various localities in the Mediterranean Sea, including type localities of some nominal taxa. We used a preliminary morphological inspection, followed by a DNA-barcoding approach to propose species hypotheses, subsequently consolidated using additional data (phylogenetic, geographic and refined morphological data). Seven species hypotheses were eventually retained within our molecularly assayed samples, versus three classical morphologically recognized species. Among these, three correspond to Aplus dorbignyi (Payreaudeau, 1826) with its hitherto unrecognized geographical cognates A. gaillardoti (Puton, 1856) (eastern Mediterranean) and Aplus nodulosus (Bivona Ant., 1832) (Sicily); two closely related, yet considerably divergent, lineages are treated as a single species under Aplus scaber (Locard, 1892); the classically admitted Aplus scacchianus (Philippi, 1844) is confirmed by molecular evidence; Mediterranean populations attributable to Aplus assimilis (Reeve, 1846) may represent either cryptic native populations or an ongoing invasion of the Mediterranean by what was hitherto considered to be a West African species; finally, specimens from the Strait of Gibraltar may represent an undescribed species, but we conservatively refrain from formally introducing it pending the analysis of more material, and it is compared with the similar Aplus campisii (Ardovini, 2014), recently described from Sicily and not assayed molecularly, and Aplus scaber.
... A possible second species of Acanthais is the species I described as Stramonita semiplicata Vermeij, 2001 from the Cantaure Formation (early Miocene) of Venezuela. Claremont et al. (2011) and Landau et al. (2016) retained this species in Stramonita Schumacher, 1817. The Cantaure fossil differs from Stramonita most obviously by having a small but distinct labral tooth in well-preserved specimens (not preserved in the type specimen) and by having a low rounded columellar fold extending into the aperture. ...
... Images courtesy of STRI database. † inadvertently excluded, but the other claimed errors concern marine sister (not strictly geminate) species that are not found on either side of the Isthmus, according to the original distribution maps (7,8), or derive from conflicting dates between Lessios* (4) and the original literature. ...
... Finally, a number of process-based approaches to test Isolation by Environment have been built (Wang and Bradburd 2014). These include Isolation by Adaptation (Nosil et al. 2008) and Isolation by Ecology (Claremont et al. 2011;Shafer and Wolf 2013), but neither have yet been applied to desert freshwaters. ...
Freshwater ecosystems in arid regions range from highly fragmented to highly connected, and connectivity has been assumed to be a major factor in the persistence of aquatic biota in arid environments. This review sought to synthesize existing research on genetic estimation of population connectivity in desert fresh-waters, identify knowledge gaps, and set priorities for future studies of connectiv-ity in these environments. From an extensive literature search, we synthesized the approaches applied, systems studied, and conclusions about connectivity reached in population genetic research concerning desert freshwater connectivity globally. We restrict our scope to obligate aquatic fauna that disperse largely via freshwa-ters and exclude those with active aerial dispersal abilities. We examined 92 papers, comprising 133 studies, published from 1987 to 2014. Most described studies of fishes and invertebrates in the deserts of Australia and North America. Connectivity declined with increasing scale, but did not differ significantly among arid regions or taxonomic classes. There were significant differences in connectiv-ity patterns between species with different dispersal abilities, and between spring and riverine habitats at local scales. Population connectivity in desert freshwaters is typically most influenced by the ecology of the species concerned and hydrological connectivity. Most studies did not assess predefined models of connectivity, but described gene flow and/or genetic structure. Climate change and anthro-pogenic impacts worldwide are likely to increase the incidence and impact of habitat fragmentation in already threatened desert freshwaters. To reduce this risk, biodiversity conservation and environmental management must address con-nectivity, but often the required information does not exist. Researchers can provide this by explicitly considering the effects of hydrology and species' ecology on connectivity, and incorporating these into connectivity models, which are vital for understanding connectivity in desert freshwaters.
... Molluscs have been used as a case study for many sequence-based taxonomic works, from tests of traditional species definitions (Barco et al. 2013a) to multigene-based species delimitation (Puillandre et al. 2009;Claremont et al. 2011;Krug et al. 2013) and biodiversity assessments (Puillandre et al. 2012;Modica et al. 2014). In contrast, DNA barcoding studies, either in its broad sense or aimed at testing specimen identification success, are relatively few. ...
Sequence-based specimen identification, known as DNA barcoding, is a common method complementing traditional morphology-based taxonomic assignments. The fundamental resource in DNA barcoding is the availability of a taxonomically reliable sequence database to use as a reference for sequence comparisons. Here we provide a reference library including 579 sequences of the mitochondrial cytochrome c oxidase subunit I (COI) for 113 North Sea mollusc species. We tested the efficacy of this library by simulating a sequence-based specimen identification scenario using Best Match (BM), Best Close Match (BCM) and All Species Barcode (ASB) criteria with three different threshold values. Each identification result was compared with our prior morphology-based taxonomic assignments. Our simulation resulted in 87.7% congruent identifications (93.8% when excluding singletons). The highest number of congruent identifications was obtained with BCM and ASB and a 0.05 threshold. We also compared identifications with genetic clustering (BINs) computed by the Barcode of Life Datasystem (BOLD). About 68% of our morphological identifications were congruent with BINs created by BOLD. Forty-nine sequences were clustered in 16 discordant BINs, and these were divided in two classes: sequences from different species clustered in a single BIN; and conspecific sequences divided in more BINs. Whereas former incongruences were likely caused by BOLD entries in need of a taxonomic update, the latter incongruences regarded taxa requiring further investigations. These include species with amphi-Atlantic distribution, whose genetic structure should be evaluated over their entire range to produce a reliable sequence-based identification system. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
... We evaluated some taxonomic assignments by comparing specimen identifications and Kimura 2-parameter (K2P) distance values obtained from the COI alignment using MEGA v. 6 (Tamura et al., 2013). We used the distance value of 0.03 as a threshold between intra-and interspecific distances among muricid species; this value is consistent with previous studies (Castelin et al., 2010;Claremont et al., 2011;Zou et al., 2012;Crocetta et al., 2012;Barco, Corso & Oliverio, 2013a;Barco et al., 2013b). ...
We investigated the relationships of the muricid subfamilies Haustrinae, Pagodulinae and the genus Poirieria using a molecular phylogenetic approach on a dataset of three mitochondrial genes (12S, 16S and COI). These taxa form a well-supported
clade within Muricidae. The phylogenetic analysis suggests that Poirieria is the sister group of Pagodulinae and that Axymene, Comptella, Pagodula, Paratrophon, Trophonella, Trophonopsis, Xymene, Xymenella, Xymenopsis and Zeatrophon are all worthy of genus-level rank within this subfamily. We propose the use of Enixotrophon for a group of species currently classified in Pagodula. The results also support a new taxonomic arrangement in Haustrinae.
Increasing habitat modification and species loss demand consistent efforts to describe and understand biodiversity patterns. The BIOTA/FAPESP Program was created in this context and it has been a successful initiative to promote studies on biodiversity and conservation in Brazil. The BIOTA/Araçá is an interdisciplinary project that provided a detailed evaluation of the biodiversity of Araçá Bay, a coastal seascape located on the North coast of the state of São Paulo, Southeast Brazil. The bay encompasses multiple habitats, such as beaches, mangroves, rocky shores, and a tidal flat, and provides important ecosystem services. Unfortunately, the bay is the subject of complex social-environmental conflicts that oppose economic, social, and environmental demands (i.e., the expansion of neighboring harbor activities vs. small-scale artisanal fisheries and protection of biodiversity). The present study presents a survey of the benthic species occurring in the different habitats of Araçá Bay, including data obtained during the BIOTA/Araçá project and previous assessments of the area. The benthic species play an important role in marine environments and studying the diversity of these organisms that live associated with the bottom is indispensable for comprehending the environment’s functioning. The macrofauna, meiofauna, and microorganisms associated with soft and hard bottom were listed, and additional information, such as the habitat and geographical distribution, were provided for each species. The checklist includes 826 species, almost 70% recorded during the BIOTA/Araçá project. The most speciose taxa were the annelids (225 spp.), mollusks (194 spp.), and crustaceans (177 spp.). Seven benthic species are endemic to Araçá Bay, 14 are considered threatened, and seven are economically exploited. Furthermore, the bay is the type locality of many taxa, and 11 new benthic species were described based on specimens sampled during the project. This project shows the importance of Araçá Bay as a unique biologically rich environment and highlights the need for conservation efforts in light of the current threats.
Species of the predatory gastropod genus Reishia Kuroda and Habe, 1971 (Muricidae) inhabit intertidal rocky shores in East Asia. Due to their highly variable external shell morphology, the taxonomy of this genus at species-level is still in need of re-evaluation. Using DNA-based delimitation methods, we aimed to ascertain the number of species of Reishia along the coasts of China and adjacent Asian areas. Also, we looked for diagnostic traits using morphology-based statistical approaches. Our genetic data suggest that the studied individuals comprised two separate species of a Reishia complex in this region, in contrast to the previously proposed four or more taxa. This conclusion is further supported by statistical analyses of shell morphological characteristics. The morphospecies R. bronni (Dunker, 1860), R. jubilaea (Tan and Sigurdsson, 1990), and R. luteostoma (Holten, 1803) were assigned to a single taxon, indicating that they might be synonyms of the same species. The morphospecies R. clavigera (Küster, 1860) singly formed one group, suggesting that it is likely a valid name. The estimated divergence time of the two identified taxa indicates that speciation might have been associated with the sea level and temperature fluctuations during the Plio-Pleistocene period. Our study on Reishia species provides crucial information for further research on the ecology, evolutionary biology, and conservation of this genus.
We provide preliminary insights into the global phylogeographic and evolutionary patterns across species of the hydrozoan superfamily Plumularioidea (Cnidaria: Hydrozoa). We analyzed 1,114 16S sequences of 198 putative species of Plumularioidea collected worldwide. We investigated genetic connections and divergence in relation to present‐day and ancient biogeographic barriers, climate changes and oceanic circulation. Geographical distributions of most species are generally more constrained than previously assumed. Some species able to raft are dispersed widely. Human‐mediated dispersal explains some wide geographical ranges. Trans‐Atlantic genetic connections are presently unlikely for most of the tropical‐temperate species, but were probably more frequent until the Miocene–Pliocene transition, before restriction of the Tethys Sea and the Central American Seaway. Trans‐Atlantic colonizations were predominantly directed westwards through (sub)tropical waters. The Azores were colonized multiple times and through different routes, mainly from the east Atlantic, at least since the Pliocene. Extant geminate clades separated by the Isthmus of Panama have predominantly Atlantic origin. Various ancient colonizations mainly directed from the Indian Ocean to the Atlantic occurred through the Tethys Sea and around South Africa in periods of lower intensity of the Benguela upwelling. Thermal tolerance, population sizes, dispersal strategies, oceanic currents, substrate preference, and land barriers are important factors for dispersal and speciation of marine hydroids.
La génétique des populations a révélé que la diversité génétique des espèces marines était très souvent distribuée de façon discrète dans l’espace, en mosaïque de patchs populationnels génétiquement homogènes délimités par des discontinuités appelées barrière au flux génique. L’objectif de cette thèse était de contribuer à mieux comprendre les processus expliquant l’origine, le maintien et la position des barrières génétiques au niveau de la zone de transition entre l’Atlantique et la Méditerranée. Dans un premier temps a été étudiée la structure génétique de la moule Mytilus galloprovincialis. Contrairement au cline abrupt et étroit reporté en Espagne, nous avons découvert en Algérie une vaste zone hybride mosaïque sur 600 km de côtes à l'Est du front océanique Almeria-Oran. Dans un deuxième temps a été menée une étude de la structure génétique du gastéropode marin Stramonita haemastoma. Nous avons découvert deux lignées cryptiques différentiellement fixées pour des haplogroupes mitochondriaux, et différenciées sur 3 marqueurs microsatellites développés dans cette thèse. La distribution spatiale en mosaïque est étonnante avec un patch de la lignée atlantique enclavé au nord de la Méditerranée occidentale et bordé par une zone hybride au sud dans la région de Valence. Ces deux études mettent en avant l’importance de l’isolement reproductif intrinsèque dans l’explication de la distribution mosaïque de la diversité génétique marine. Bien que les frontières entre patchs correspondent à des barrières physiques à la dispersion ou à des écotones, l’hydrographie et l’environnement n’expliquent sans doute que la position des discontinuités génétiques mais ni leur origine ni leur maintien.
In recent years, coral associated viruses could play primal role in protecting coral health, yet their ecological traits are poorly investigated. In this study, the abundance and life cycles (lysogeny and lytic) of viruses associated with contrasted coral health states (healthy and bleached) were studied and compared. In addition, the density of bacteria and Symbiodium were also be determined by epifluorescence microscopy. The results showed that viral abundance increased 1.2 times and bacterial abundance decreased 0.6 times in healthy corals compared to bleached ones. The number of Symbiodinium significantly reduced 5.6 times in bleached corals compared to healthy corals. One of the most important results in this study was the coexistence of the both lysogenic and lytic viruses in healthy coral. The fraction of lysogenic bacteria was 2 times higher in healthy corals than in bleached ones. Healthy corals carried 3.5-fold more viral production than the diseased ones. Overall, the results showed that, in healthy state, corals might be a favorable environment for viral infection, promoting the development of both temperate and virulent phages. This coexistence might be crucial for coral viability through the complex links with their coral-associated bacterial hosts.
Como o objetivo de contribuir para o conhecimento das comunidades marinhas incrustantes, o presente estudo analisou a variação temporal em comunidades de moluscos encontradas em placas de recrutamento trimestrais e anuais instaladas em uma região portuária no nordeste do Brasil. Um conjunto de 30 placas artificiais foi submerso entre os pilares do píer a uma profundidade aproximada de 6 m. A cada três meses, um subconjunto de 15 placas era removido para o exame da biota presente. O segundo subconjunto de 15 placas foi deixado submerso por um ano, e depois removido para análise. No mesmo dia em que as placas eram removidas, elas eram substituídas por novas placas. Doze remoções/reposições de placas foram realizadas de outubro de 2009 a novembro de 2012. Duas classes de Mollusca foram encontradas nos painéis de recrutamento: Gastropoda e Bivalvia. Trinta táxons foram encontrados nas placas trimestrais e 23 táxons nas placas anuais. Duas espécies nãonativas da costa brasileira foram encontradas: Isognomon bicolor e Eualetes tulipa. Nas placas trimestrais, a espécie mais comum e abundante foi a ostra Crassostrea brasiliana e a espécie mais abundante nas placas anuais foi o bivalve Musculus lateralis.
The genetic diversity and population genetic structures of Drupella cornus populations from six localities in the northern Gulf of Eilat (GOE) and five localities in Tanzania (269 individuals) were investigated using mitochondrial cytochrome c oxidase subunit I (COI) gene sequences. Overall, 107 haplotypes, 47 in GOE and 61 in Tanzania, revealed similar haplotype diversity for the D. cornus populations within each location (0.9 ± 0.00025 and 0.903 ± 0.00078 respectively), with only a single haplotype shared between the two regions. Network analysis for the 107 COI haplotypes displayed two major clades separated by nine mutations, and Bayesian analyses of population structures revealed two clusters highly correlated with the collecting region. Analysis of molecular variance showed that 73% of the molecular variance for all Drupella populations is based on differences among regions. Within regions, most of the molecular variance is based on within population differences, north vs south in Tanzania (89%) and Israel vs Jordan in GOE (98%). Fu’s Fs and Tajima’s D values for all populations were negative, suggesting that the Drupella populations in both regions underwent population expansion or purifying selection. Based on the differences in genetic structuring within populations, the study strongly recommends application of conservation approaches that suit the description of the population in each region.
Conus is the largest genus of animals in the sea, occurring throughout the world’s tropical and subtropical oceans and contributing significantly to marine biodiversity. The shells of these marine mollusks are prized for their amazing variety and extraordinary beauty. The neurotoxic venoms they produce—injected by a hollow, harpoon-like tooth into prey animals that are then paralyzed and swallowed whole—have a range of pharmaceutical applications, from painkillers to antidepressants. This beautifully illustrated book identifies 53 valid species of the southeastern United States and the Caribbean, a region that supports a diverse but taxonomically challenging group of Conus. Introductory chapters cover the evolution and phylogeny of the genus, and notes on methodology are provided. Detailed species accounts describe key identification features, taxonomy, distribution, ecology, toxicology, life history, and evolutionary relationships. The book includes more than 2,100 photos of shells on 109 splendid color plates; more than 100 additional photos, many depicting live animals in color; and 35 color distribution maps. Identifies 53 valid species—the first reassessment of western Atlantic Conus in more than seventy years Features more than 2,100 photos of shells on 109 color plates Blends the traditional shell-character approach to identification with cutting-edge shell and radular tooth morphometrics and molecular genetic analyses Includes color images of live animals as well as color distribution maps.
Corallivorous Drupella (Muricidae) snails at Koh Tao are reported to have extended their range of prey species following a major coral bleaching event in 2010. Populations of their preferred Acropora prey had locally diminished in both size and abundance, and the snails had introduced free-living mushroom corals in their diet. Although the coral community largely recovered, the Drupella population grew and reached outbreak proportions. For this study, corallivorous muricids at Koh Tao were studied more intensively to examine their identities, distribution and prey choice four years after the bleaching event. Drupella rugosa was identified as the major outbreak species and occurred at densities > 3 m -2 in depth ranges of 2-5 and 5-8 m. The density of D. rugosa was related to the live coral cover, Acropora colony density, and depth. Resource selection ratios revealed that species of Acropora, Psammocora and Pavona corals were attacked more frequently than would be expected based on their availability. Strikingly, fungiid corals were now avoided as prey in the recovered coral community, despite them being part of the preferred diet directly after the bleaching. Although D. rugosa showed a clear prey preference, it appears to be plastic by changing with prey availability. The muricids Drupella margariticola and Morula spinosa occurred in much lower densities and were less often associated with corals. Snails of the opportunistic corallivore D. margariticola usually co-occurred in D. rugosa aggregations, although they also formed feeding aggregations by themselves. Whether M. spinosa generally associates with corals as a corallivore or a scavenger has yet to be determined. Molecular analyses did not reveal cryptic speciation among snails sampled from different coral hosts and also no geographic variation. The present study also showed that corallivory is more common among D. margariticola and M. spinosa than previously known.
This is the last in a series of systematic accounts of the 60 worldwide species of the littorinid genus Echinolittorina. The taxonomy and distributions of molluscs in the eastern Atlantic are poorly known and littorinids are no exception. Recent molecular studies have clarified the number of species and their relationships, and are used as the basis of this systematic account. Detailed morphological descriptions are provided here for the eight known living species in the tropical and warm temperate eastern Atlantic, from the Mediterranean to Namibia, including the islands of Cape Verde, Canaries, São Tomé, Ascension and St Helena. The descriptions give details of shell, operculum, pigmentation of headfoot, reproductive anat-omy, spermatozoa, egg capsules and radulae. Diagnoses include reference to mitochondrial gene sequences (COI). A key is based on shell, penial shape, pallial oviduct and geographical distribution, and includes all other littorinid species (mem-bers of genera Tectarius, Afrolittorina, Littoraria, Melarhaphe and Littorina) found in the eastern Atlantic region. Three new species are described: E. peregrinator, E. caboverdensis and E. soroziczac. One name change is proposed: Littorina lemniscata Philippi, 1846 was formerly listed as a junior synonym of E. miliaris from Ascension Island, but examination of types has shown this to be a senior synonym of E. galapagiensis (Stearns, 1892) from the tropical eastern Pacific, which should now be called E. lemniscata. Full synonymies are given for all taxa, and the taxonomic, evolutionary and ecological literature reviewed. Distribution maps are based on examination of 312 samples and on reliable literature records. These reveal close correspondence with the biogeographic division of the region into three provinces (Lusitanian; West African; St Helena and Ascension). The allopatry of sister taxa is maintained by barriers of ocean currents, river deltas and distri-bution of continental and oceanic conditions. The eight species belong to four clades (E. peregrinator; E. soroziczac; E. punctata group; E. granosa group), each of which is sister to one or more species from the western Atlantic or belongs to a clade with western Atlantic and eastern Pacific distribution. This supports trans-Atlantic dispersal from the west, esti-mated to have occurred in the Early Miocene and in the Plio-Pleistocene.
The pantropical sea urchin genus Eucidaris contains four currently recognized species, all of them allopatric: E. metularia in the Indo-West Pacific, E. thouarsi in the eastern Pacific, E. tribuloides in both the western and eastern Atlantic, and E. clavata at the central Atlantic islands of Ascension and St. Helena. We sequenced a 640-bp region of the cytochrome oxidase I (COI) gene of mitochondrial DNA to determine whether this division of the genus into species was confirmed by molecular markers, to ascertain their phylogenetic relations, and to reconstruct the history of possible dispersal and vicariance events that led to present-day patterns of species distribution. We found that E. metularia split first from the rest of the extant species of the genus. If COI divergence is calibrated by the emergence of the Isthmus of Panama, the estimated date of the separation of the Indo-West Pacific species is 4.7-6.4 million years ago. This date suggests that the last available route of genetic contact between the Indo-Pacific and the rest of the tropics was from west to east through the Eastern Pacific Barrier, rather than through the Tethyan Sea or around the southern tip of Africa. The second cladogenic event was the separation of eastern Pacific and Atlantic populations by the Isthmus of Panama. Eucidaris at the outer eastern Pacific islands (Galapagos, Isla del Coco, Clipperton Atoll) belong to a separate clade, so distinct from mainland E. thouarsi as to suggest that this is a different species, for which the name E. galapagensis is revived from the older taxonomic literature. Complete lack of shared alleles in three allozyme loci between island and mainland populations support their separate specific status. Eucidaris galapagensis and E. thouarsi are estimated from their COI divergence to have split at about the same time that E. thouarsi and E. tribuloides were being separated by the Isthmus of Panama. Even though currents could easily convey larvae between the eastern Pacific islands and the American mainland, the two species do not appear to have invaded each other's ranges. Conversely, the central Atlantic E. clavata at St. Helena and Ascension is genetically similar to E. tribuloides from the American and African coasts. Populations on these islands are either genetically connected to the coasts of the Atlantic or have been colonized by extant mitochondrial DNA lineages of Eucidaris within the last 200,000 years. Although it is hard to explain how larvae can cross the entire width of the Atlantic within their competent lifetimes, COI sequences of Eucidaris from the west coast of Africa are very similar to those of E. tribuloides from the Caribbean. FST statistics indicate that gene flow between E. metularia from the Indian Ocean and from the western and central Pacific is restricted. Low gene flow is also evident between populations of E. clavata from Ascension and St. Helena. Rates of intraspecific exchange of genes in E. thouarsi, E. galapagensis, and E. tribuloides, on the other hand, are high. The phylogeny of Eucidaris confirms Ernst Mayr's conclusions that major barriers to the dispersal of tropical echinoids have been the wide stretch of deep water between central and eastern Pacific, the cold water off the southwest coast of Africa, and the Isthmus of Panama. It also suggests that a colonization event in the eastern Pacific has led to speciation between mainland and island populations.
After the middle Pliocene uplift of the Central American seaway (3.1 to 3.6 million years ago), the western Atlantic fauna became isolated from that of the eastern Pacific, but connections with the tropical Indo-West-Pacific and eastern Atlantic were maintained. By analyzing the distibution, fossil record, and relationships of shallow-water shell-bearing molluscs (those living in less than 100 m depth) in the western Atlantic, we ascertained the extent to which the western Atlantic has served as a recipient and as a donor region for invading taxa
At least 33 species in the western Atlantic are late Pliocene or Pleistocene invaders from the Indo-West-Pacific (17 species) or eastern Atlantic (16 species), whereas at least 39 species dispersed eastward across the Atlantic from the Americas to West Africa. Eleven species derived from the Indo-West-Pacific are included in both tallies, because they probably first dispersed westward from the Indian Ocean around southern Africa to Brazil and the Caribbean region before spreading eastward across the Atlantic to West Africa. Most of this dispersal is probably by means of planktonic larvae, but some species could have been spread as rafting adults.
Oceanic currents and prior extinction histories determine the pattern of interchange among tropical marine biotas. Within the tropics, the western Atlantic suffered the greatest molluscan extinctions since the early Pliocene (about 60 to 70%); it is also the region in which the great majority of immigrants have become common and geographically widespread. Extinction in the eastern Atlantic, eastern Pacific, and Indo-West-Pacific has been much less, and immigrants to these regions often have restricted geographical distribution there, and could be represented by populations that are not self-sustaining.
The ‘Eastern Pacific Barrier’ (EPB), 5400 km of uninterrupted deep water between the central and eastern Pacific, constitute the greatest marine obstacle to the dispersal of shallow–water organisms. However, some species are found on both sides o the EPB. These ‘transpacific’ species are considered by ‘dispersal’ biogeographers as evidence of invasions through the barrier.
‘Vicariance’ biogeographers, on the other hand, think that transpacific species are morphologically conservative remnant of previously continuous distributions. We compared nucleotide sequences in a 642 bp region of mitochondrial DNA, and electrophoreticall detected alleles in 17 enzymatic loci of central and eastern Pacific populations of Echinothrix diadema, an Indo–Pacific sea urchin recently reported from the eastern Pacific. Both types of molecules produced clear evidence o massive, recent gene flow across the EPB. Thus, rather than being isolated relicts of Tethyan distributions, conspecific population from the eastern and central Pacific are genetically connected. Though the EPB is biogeographically important as a cause o speciation in many groups, it allows genetic connections in others, possibly through larval transport during El Niño events.
The earliest known members of the Thais clade of rapanine muricid neogastropods comprise four species from the Cantaure Formation (early Miocene: Burdigalian) of Venezuela; three of these species are new. Neorapana rotundata Gibson-Smith et al., 1997, is most closely related to the Recent Pacific Mexican N. tuberculata (Sowerby, 1835), and represents the only known Atlantic occurrence of the genus. Thais brevicula new species is closest to T. callaoensis (Gray, 1828) from the Recent of northern Peru and the Galápagos. A review of the genus Thais indicates that the typical members of this group occur in the South Atlantic, West Africa, and eastern Pacific, but not in the Recent fauna of the southern Caribbean. Stramonita bifida new species is a large species related to the Recent S. haemastoma floridana (Conrad, 1837), which occurs throughout the Caribbean. A review of American species of Stramonita indicates that the taxon S. biserialis (de Blainville, 1832) from the Recent fauna of the eastern Pacific, and the taxon S. h. haemastoma (Linnaeus, 1767), may each be composed of more than one species despite the teleplanic dispersal of their larvae. Stramonita semiplicata new species is closely related to the Recent S. bicarinata (de Blainville, 1832) from the South Atlantic, and represents a lineage that occurred in the Caribbean region until at least the late Miocene. It may have given rise to the eastern Pacific genus Acanthais. The higher diversity and greater antipredatory specialization of eastern Pacific as compared to western Atlantic members of the Thais clade may have resulted from higher post-Miocene rates of speciation and lower extinction rates in the eastern Pacific.
Members of the neogastropod muricid subfamily Rapaninae are abundant, shallow-water predators whose phylogeny was previously investigated by Kool (1993b), who used mainly anatomical characters. In order to deepen understanding of the evolution of this important clade and to incorporate functional, ecological, and fossil evidence, we performed a phylogenetic analysis based on 34 shell characters in 45 genus-level taxa, including five muricid outgroups. Cladograms based on shell characters alone differed from those founded on anatomical features, and these analyses differed from the phylogenetic reconstruction combining all available morphological evidence. The preferred cladogram incorporates all evidence and reveals a “Thais group” and an “Ergalatax clade” that both emerge from the derived portion of a more primitive, paraphyletic group of other rapanines. The Ocenebrinae, the other four outgroup taxa, and three ergalataxine taxa all lie outside the rapanine clade that includes the remaining ergalataxines as a derived subclade. We used the phylogenetic results to probe aspects of the ecological history of the Rapaninae. Our data imply that antipredatory shell defenses (elongated aperture, denticles on the inner side of the outer lip, and robust external spines and tubercles) evolved multiple times, mainly in post–early Miocene clades in the Indo–West Pacific region. These results support earlier nonphylogenetic inferences. We compared known prey types and methods of predation of living rapanines with their distribution on our phylogenetic tree. The plesiomorphic mode of feeding in the Rapaninae is drilling of hard-shelled prey. Feeding by other means and on such soft-bodied prey as sipunculan and polychaete worms evolved several times independently among post–early Miocene rapanines in the Indo–West Pacific. Methods of predation on hard-shelled prey that involve edge-drilling or attack by way of the aperture also evolved independently several times, but did so throughout the geographical range of the subfamily. Specialization for life on the upper shore occurred in at least eight lineages, all but two of which are confined to the Indo–West Pacific. Ecological diversification of the Rapaninae was therefore most common in the tropical Indo–West Pacific during and after early Miocene time. This diversification occurred in a setting of already high biological diversity and intense competition and predation.
Understanding the patterns, causes, and consequences of biotic interchange - the movement of species between neighboring biotas - is crucial for evaluating the effects of human-introduced species in the modern biosphere. Since at least the early Miocene, the tropical and subtropical western Atlantic has comprised two biogeographic provinces, the Gatunian (including the Caribbean) and the Caloosahatchian (North Carolina to Florida and the Yucatán peninsula). Although these adjacent provinces are not separated by a land barrier, exchange of species between them has been limited and intermittent. A synthesis of taxonomic, phylogenetic, stratigraphic, and biogeographic data on six gastropod and two bivalve groups reveals a dramatic shift in the pattern of interchange between these provinces. About 31% of early Miocene Caloosahatchian subgenus- and species-group-level taxa invaded the Gatunian Province by the late Miocene, but no taxa extended their ranges in the opposite direction. Beginning in the early Pliocene and continuing into the early Pleistocene, 40 taxa (roughly one-third of Gatunian diversity) invaded the Caloosahatchian Province from the Caribbean, whereas only four taxa extended their range from Florida into the Caribbean. Comparisons between the ranked percentage of Gatunian invaders in Florida and the magnitude of regional extinction there for each of four middle Pliocene to early Pleistocene intervals reveal no consistent relation between invasion and prior or concurrent extinction. During the Pliocene, invaders not only compensated for extinctions, but also accounted for almost all the observed increase in standing diversity in Florida. Only after the large extinction event at the end of the Pliocene did invaders from the Gatunian Province not fully compensate for the loss of species. Although the Miocene interaction between the Gatunian and Caloosahatchian biotas involved two fully tropical entities, the Plio-Pleistocene interaction exemplifies a general pattern in which tropical species often spread to higher latitudes during warm intervals, but warm-temperate or subtropical species rarely become established in the Tropics. Some evidence indicates that tropical Caribbean molluscs are exposed and adapted to more intense competition and predation than their subtropical counterparts in Florida, implying a role for individual-level biotic interactions in determining the predominant direction of interchange. Intensification of north-flowing currents in the western Atlantic may also contribute to the nearly one-way movement of taxa from the Caribbean to Florida during the Pliocene and early Pleistocene. The changing pattern of interchange from the Miocene to the Pliocene further reflects a change in the geography of species richness, with the richer province serving as the chief donor and the province with lower diversity acting as the main recipient of invaders. Diversity, ocean circulation, and the competitive environment thus account for the observed switch in the predominant direction of invasion in the western Atlantic during the Neogene. The fact that almost 90% of Gatunian immigrants to Florida differentiated taxonomically there indicates that invasion is intermittent. Long-term consequences of this and many other cases of interchange between provinces include enrichment of the regional and global species pool and the spread of adaptations reflecting intense competition and predation.
A\e southern oyster drills, Stramonita haemastoma floridana (Conrad, 1837), have been collected from two Chesapeake Bay western shore tributaries. Four specimens were collected be- tween Brown Shoal and Thomas Rock in the lower James River in February 2005. Thirteen live southern oyster drills were collected from Back Biver in April 2006. Identification of these drills as Stramonita haemastoma floridana has been confirmed using DNA bar-coding data. Southern oyster drills collected in Chesapeake Bay are genetically nearly identical to populations from the Atlantic coast, and differ significantly from popula- tions from the Azores and from the Gulf of Mexico. These collections mark the first reported records of live southern oys- ter drills from within the Chesapeake Bay estuar)'. It is un- known if these drills represent isolated introductions or expan- sions of the northern range this species. Water temperature patterns in Chesapeake Bay and the Mid-Atlantic Bight from 1990-2005 are similar to those obser\'ed in the late 1950s when Stramonita haemastoma floridana was first found living in Chincoteague Bay, Maryland.
Successful dispersal between populations leaves a genetic wake that can reveal historical and contemporary patterns of connectivity. Genetic studies of differentiation in the sea suggest the role of larval dispersal is often tempered by adult ecology, that changes in differentiation with geographic distance are limited by disequilibrium between drift and migration, and that phylogeographic breaks reflect shared barriers to movement in the present more than common historical divisions. Recurring complications include the presence of cryptic species, selection on markers, and a failure to account for differences in heterozygosity among markers and species. A better understanding of effective population sizes is needed. Studies that infer parentage or kinship and coalescent analyses employing more markers are both likely to spur progress, with analyses based on linkage disequilibrium potentially bridging results from these studies and reconciling patterns that vary at ecological and evolutionary timescales.
Population connectivity plays significant roles on both evolutionary and ecological time-scales, however quantifying the magnitude and pattern of demographic exchange between populations of marine organisms is hindered by the difficulty of tracking the trajectory and fate of propagules. We explore biophysical correlates of population substructure to determine how well pelagic larval duration (PLD) correlates with population genetic estimates of connectivity in a sample of 300 published studies. In direct contrast to a number of previous reviews, we find that average PLD is poorly correlated with genetic structure (FST). Furthermore, even this weak correlation is anchored by non-pelagic dispersal, because removal of the zero PLD class (direct developers) from the analysis resulted in a non-significant relationship between FST and PLD. For species in which minimum, maximum and mean PLD were available, it is noteworthy that both minimum and maximum PLD are better correlated with FST than the mean larval duration, which has been used in all such previous studies. A 3-way ANCOVA reveals that genetic marker class (mtDNA, allozymes, and microsatellites) as opposed to habitat or swimming ability, are responsible for most of the variation in FST (F = 7.113, df = 2, p = 0.001), with higher values of FST obtained from mtDNA than with either microsatellites or allozymes (which were not significantly different). Our meta-analysis refutes previous reviews suggesting that PLD is a good predictor of gene flow in marine systems.
After a 12-million-year (My) process, the Central American Isthmus was completed 2.8 My ago. Its emergence affected current flow, salinity, temper-ature, and primary productivity of the Pacific and the Atlantic and launched marine organisms of the two oceans into independent evolutionary trajec-tories. Those that did not go extinct have diverged. As no vicariant event is better dated than the isthmus, molecular divergence between species pairs on its two coasts is of interest. A total of 38 regions of DNA have been sequenced in 9 clades of echinoids, 38 of crustaceans, 42 of fishes, and 26 of molluscs with amphi-isthmian subclades. Of these, 34 are likely to have been separated at the final stages of Isthmus completion, 73 split earlier and 8 maintained post-closure genetic contact. Reproductive isolation has developed between several isolates, but is complete in only the sea urchin Diadema. Adaptive divergence can be seen in life history parameters. Lower primary productivity in the Caribbean has led to the evolution of higher levels of maternal provisioning in marine invertebrates.
Aim Our aims were: (1) to reconstruct a molecular phylogeny of the cephalaspidean opisthobranch genus Bulla , an inhabitant of shallow sedimentary environments; (2) to test if divergence times are consistent with Miocene and later vicariance among the four tropical marine biogeographical provinces; (3) to examine the phylogenetic status of possible Tethyan relict species; and (4) to infer the timing and causes of speciation events.
Location Tropical and warm‐temperate regions of the Atlantic, Indo‐West Pacific, Australasia and eastern Pacific.
Methods Ten of the 12 nominal species of Bulla were sampled, in a total sample of 65 individuals, together with cephalaspidean outgroups. Phylogenetic relationships were inferred by Bayesian analysis of partial sequences of the mitochondrial cytochrome c oxidase I (COI) and 16S rRNA and nuclear 28S rRNA genes. Divergence times and rates of evolution were estimated using uncorrelated relaxed‐clock Bayesian methods with fossil calibrations (based on literature review and examination of fossil specimens), implemented in beast . The geographical pattern of speciation was assessed by estimating the degree of overlap between sister lineages.
Results Four clades were supported: Indo‐West Pacific (four species), Australasia (one species), Atlantic plus eastern Pacific (three species) and Atlantic (two species), with estimated mean ages of 35–46 Ma. Nominal species were monophyletic, but deep divergences were found within one Indo‐West Pacific and one West Atlantic species. Species‐level divergences occurred in the Miocene or earlier. The age of a sister relationship across the Isthmus of Panama was estimated at 7.9–32.1 Ma, and the divergence of a pair of sister species on either side of the Atlantic Ocean occurred 20.4–27.2 Ma.
Main conclusions Fossils suggest that Bulla originated in the Tethys realm during the Middle Eocene. Average ages of the four main clades fall in the Eocene, and far pre‐date the 18–19 Ma closure of the Tethys Seaway. This discrepancy could indicate earlier vicariant events, selective extinction or errors of calibration. Similarly, the transisthmian divergence estimate far pre‐dates the uplift of the Panamanian Isthmus at about 3 Ma. Speciation events occurred in the Miocene, consistent with tectonic events in the central Indo‐West Pacific, isolation of the Arabian Sea by upwelling and westward trans‐Atlantic dispersal. Differences in habitat between sister species suggest that ecological speciation may also have played a role. The basal position of the Australasian species supports its interpretation as a Tethyan relict.
Aim In this study, I examined the relative contributions of geography and ecology to species diversification within the genus Nerita, a prominent clade of marine snails that is widely distributed across the tropics and intertidal habitats. Specifically, I tested whether geographical patterns of speciation correspond primarily to allopatric or sympatric models, and whether habitat transitions have played a major role in species diversification.
Location Indo-West Pacific, eastern Pacific, Atlantic, tropical marine intertidal.
Methods I used a previously reconstructed molecular phylogeny of Nerita as a framework to assess the relative importance of geographical and ecological factors in species diversification. To evaluate whether recently diverged clades exhibit patterns consistent with allopatric or sympatric speciation, I mapped the geo-graphical distribution of each species onto the species-level phylogeny, and examined the relationship between range overlap and time since divergence using age–range correlation analyses. To determine the relative contribution of habitat transitions to divergence, I traced shifts in intertidal substrate affinity and vertical zonation across the phylogeny using parsimony, and implemented randomization tests to evaluate the resulting patterns of ecological change.
Results Within the majority of Nerita clades examined, age–range correlation analysis yielded a low intercept and a positive slope, similar to that expected under allopatric speciation. Approximately 75% of sister species pairs have maintained allopatric distributions; whereas more distantly related sister taxa often exhibited complete or nearly complete geographical overlap. In contrast, only 19% of sister species occupy distinct habitats. For both substrate and zonation, habitat transitions failed to concentrate towards either the tips or the root of the phylogeny. Instead, habitat shifts have occurred throughout the history of Nerita, with a general transition from the lower and mid-littoral towards the upper and supra-littoral zones, and multiple independent shifts from hard (rock) to softer substrates (mangrove, mud and sand).
Main conclusions Both geography and ecology appear to have influenced diversification in Nerita, but to different extents. Geography seems to play a principal role, with allopatric speciation driving the majority of Nerita divergences. Habitat transitions appear insignificant in shaping the early and recent history of speciation, and promoting successive diversification in Nerita; however, shifts may have been important for respective divergences (i.e. those that correspond to the transitions) and enhancing diversity throughout the clade.
Nine collections in the southeastern USA of the thaidid molluscStramonita haemastoma, comprising 963 individuals, were made between June 1988 and November 1989, and examined for allozyme variation at 18 electrophoretically-detected loci. Two genetically-differentiated groups were identified and are referred to ascanaliculata-like andfloridana-like snails, based on previously-described subspecies ofS. haemastoma. The two groups were differentiated genetically at a level that is characteristic of congeneric species in other molluscan taxa. The two groups maintained their genetic differences in areas of sympatry, although rare hybrid individuals occurred (about 1.2% of the total set). Shell and radular characters showed little variation within or between the two groups. Within each group, allozyme allele frequencies showed little geographic variation across distances as great as 1 500 km. This result is consistent with the suggestion that species with planktonic larvae (such asS. haemastoma) should have higher rates of gene flow than related brooding species.
Containing much original, previously unpublished research, this book describes the conspicuous. colourful, and ecologically important snail genus Conus. It provides what is probably the best and most extensive data set of life parameters available from any tropical invertebrate taxon. The conclusions drawn are likely to apply to many coral-reef invertebrates and thus ensure the book's significance for all those interested in the study of biodiversity.
The littorinid genus Echinolittorina is of global distribution on rocky shores in topical latitudes, but in terms of the number of sympatric species and of phylogenetic diversity the genus reaches is greatest richness in the western Atlantic biogeographic region. The systematics of Echinolittorina in the western Atlantic have been controversial, owing to both intraspecific variability and convergence in traditional taxonomic characters of the shell and radula, and also to lack of anatomical descriptions. As a result of recent molecular studies the species can now be defined. Detailed morphological descriptions are provided here for the ten known living species, including details of shell, operculum, pigmentation of headfoot, reproductive anatomy, spermatozoa, egg capsules and radulae. Diagnoses include reference to mitochondrial gene sequences (COI). A key is based on shells, opercula, penial shapes and geographical distributions, and includes all other littorinid species (members of genera Littoraria, Cenchritis and Tectarius) found in the western Atlantic region, to avoid confusion. Based on molecular phylogenetic analysis, the ten species are assigned to four subgenera: Fossarilittorina, Lineolittorina n. subgen., Amerolittorina n. subgen. and Echinolittorina. One new species is described: E. placida n. sp. from the Gulf of Mexico. One name change is proposed: E. jamaicensis (C.B. Adams, 1850) replaces Nodilittorina riisei (Mörch, 1876), N. glaucocincta (Mörch, 1876) and N. mordax Bandel & Kadolsky, 1982. It is confirmed that the forms previously discriminated as Nodilittorina tuberculata (Menke, 1828) and N. dilatata (d’Orbigny, 1842) belong to a single species, E. tuberculata (Menke, 1828). These five ‘species’ of ‘Nodilittorina’ were diagnosed solely by striking differences in their radulae in a previous taxonomic study, but it is here shown that this variation is intraspecific, although the cause is unknown. New COI sequences are included in a phylogenetic analysis to support this conclusion. Full synonymies are given for all taxa, and the taxonomic, evolutionary and ecological literature reviewed. Distribution maps are based on examination of 1091 samples and on reliable literature records. The biogeography of the western Atlantic marine region is discussed, based on the ten distribution maps, emphasizing the mutual isolation of the Gulf of Mexico, Caribbean Sea, Brazilian mainland and Brazilian oceanic archipelagos, and the significance of the contrast between oceanic and continental distribution patterns. In E. mespillum there is a conspicuous polymorphism of shell colour with a geographical pattern, and mimicry is suggested. The natural distribution of E. placida n. sp. is on the sparse rocky outcrops of the southern Gulf of Mexico, but following the widespread construction of sea walls along the sedimentary coastline of the Gulf since the late nineteenth century, this species has spread for 4500 km around the Gulf, to Florida and as far as North Carolina in about 100 years. Occasional black shells are found within populations of normally variegated Echinolittorina species, which has not been recorded in congeners from other oceans.
The pantropical sea urchin genus Eucidaris contains four currently recognized species, all of them allopatric: E. metularia in the Indo-West Pacific, E. thouarsi in the eastern Pacific, E. tribuloides in both the western and eastern Atlantic, and E. clavata at the central Atlantic islands of Ascension and St. Helena. We sequenced a 640-bp region of the cytochrome oxidase I (COI) gene of mitochondrial DNA to determine whether this division of the genus into species was confirmed by molecular markers, to ascertain their phylogenetic relations, and to reconstruct the history of possible dispersal and vicariance events that led to present-day patterns of species distribution. We found that E. metularia split first from the rest of the extant species of the genus. If COI divergence is calibrated by the emergence of the Isthmus of Panama, the estimated date of the separation of the Indo-West Pacific species is 4.7-6.4 million years ago. This date suggests that the last available route of genetic contact between the Indo-Pacific and the rest of the tropics was from west to east through the Eastern Pacific Barrier, rather than through the Tethyan Sea or around the southern tip of Africa. The second cladogenic event was the separation of eastern Pacific and Atlantic populations by the Isthmus of Panama. Eucidaris at the outer eastern Pacific islands (Galapagos, Isla del Coco, Clipperton Atoll) belong to a separate clade, so distinct from mainland E. thouarsi as to suggest that this is a different species, for which the name E. galapagensis is revived from the older taxonomic literature. Complete lack of shared alleles in three allozyme loci between island and mainland populations support their separate specific status. Eucidaris galapagensis and E. thouarsi are estimated from their COI divergence to have split at about the same time that E. thouarsi and E. tribuloides were being separated by the Isthmus of Panama. Even though currents could easily convey larvae between the eastern Pacific islands and the American mainland, the two species do not appear to have invaded each other's ranges. Conversely, the central Atlantic E. clavata at St. Helena and Ascension is genetically similar to E. tribuloides from the American and African coasts. Populations on these islands are either genetically connected to the coasts of the Atlantic or have been colonized by extant mitochondrial DNA lineages of Eucidaris within the last 200,000 years. Although it is hard to explain how larvae can cross the entire width of the Atlantic within their competent lifetimes, COI sequences of Eucidaris from the west coast of Africa are very similar to those of E. tribuloides from the Caribbean. FST statistics indicate that gene flow between E. metularia from the Indian Ocean and from the western and central Pacific is restricted. Low gene flow is also evident between populations of E. clavata from Ascension and St. Helena. Rates of intraspecific exchange of genes in E. thouarsi, E. galapagensis, and E. tribuloides, on the other hand, are high. The phylogeny of Eucidaris confirms Ernst Mayr's conclusions that major barriers to the dispersal of tropical echinoids have been the wide stretch of deep water between central and eastern Pacific, the cold water off the southwest coast of Africa, and the Isthmus of Panama. It also suggests that a colonization event in the eastern Pacific has led to speciation between mainland and island populations.
A technique is presented for the partitioning of nucleotide diversity into within- and between-population components for the case in which multiple populations have been surveyed for restriction-site variation. This allows the estimation of an analogue of FST at the DNA level. Approximate expressions are given for the variance of these estimates resulting from nucleotide, individual, and population sampling. Application of the technique to existing studies on mitochondrial DNA in several animal species and on several nuclear genes in Drosophila indicates that the standard errors of genetic diversity estimates are usually quite large. Thus, comparative studies of nucleotide diversity need to be substantially larger than the current standards. Normally, only a very small fraction of the sampling variance is caused by sampling of individuals. Even when 20 or so restriction enzymes are employed, nucleotide sampling is a major source of error, and population sampling is often quite important. Generally, the degree of population subdivision at the nucleotide level is comparable with that at the haplotype level, but significant differences do arise as a result of inequalities in the genetic distances between haplotypes.
The earliest known members of the Thais clade of rapanine muricid neogastropods comprise four species from the Cantaure Formation (early Miocene: Burdigalian) of Venezuela; three of these species are new. Neorapana rotundata Gibson-Smith et al., 1997, is most closely related to the Recent Pacific Mexican N. tuberculata (Sowerby, 1835), and represents the only known Atlantic occurrence of the genus. Thais brevicula new species is closest to T. callaoensis (Gray, 1828) from the Recent of northern Peru and the Galápagos. A review of the genus Thais indicates that the typical members of this group occur in the South Atlantic, West Africa, and eastern Pacific, but not in the Recent fauna of the southern Caribbean. Stramonita bifida new species is a large species related to the Recent S. haemastoma floridana (Conrad, 1837), which occurs throughout the Caribbean. A review of American species of Stramonita indicates that the taxon S. biserialis (de Blainville, 1832) from the Recent fauna of the eastern Pacific, and the taxon S. h. haemastoma (Linnaeus, 1767), may each be composed of more than one species despite the teleplanic dispersal of their larvae. Stramonita semiplicata new species is closely related to the Recent S. bicarinata (de Blainville, 1832) from the South Atlantic, and represents a lineage that occurred in the Caribbean region until at least the late Miocene. It may have given rise to the eastern Pacific genus Acanthais. The higher diversity and greater antipredatory specialization of eastern Pacific as compared to western Atlantic members of the Thais clade may have resulted from higher post-Miocene rates of speciation and lower extinction rates in the eastern Pacific.
Stramonita penelaevis new species from the Caloosahatchee Formation of southeastern Florida is a smooth rocky-shore muricid gastropod. Stramonita penelaevis, the first member of its clade from Florida, represents a group that has become geographically restricted to the South Atlantic since the late Pliocene.
New fossils of Stramonita (Schumacher, 1817) from southern Peru and Chile provide evidence that modern S. chocolata (Duclos, 1832) evolved during the late Pliocene on the coast of western South America. Three new species, S. caracolensis, sp. nov., S. huaricanganensis, sp. nov., and S. zinsmeisteri, sp. nov., are short-lived late Pliocene taxa that morphologically link S. chocolata to older populations of S. biserialis (Blainville, 1832). The appearance of morphological novelty in South American Stramonita, the only entirely temperate lineage of the genus, coincides with a major species-level extinction of Peruvian mollusks. One new feature, a thicker, more refractory, outer calcitic layer, may have been an adaptive response to severe bioerosion caused by boring demosponges and polychaetes.
This is the last in a series of systematic accounts of the 60 worldwide species of the littorinid genus Echinolittorina. The taxonomy and distributions of molluscs in the eastern Atlantic are poorly known and littorinids are no exception. Recent molecular studies have clarified the number of species and their relationships, and are used as the basis of this systematic account. Detailed morphological descriptions are provided here for the eight known living species in the tropical and warm temperate eastern Atlantic, from the Mediterranean to Namibia, including the islands of Cape Verde, Canaries, São Tomé, Ascension and St Helena. The descriptions give details of shell, operculum, pigmentation of headfoot, reproductive anat-omy, spermatozoa, egg capsules and radulae. Diagnoses include reference to mitochondrial gene sequences (COI). A key is based on shell, penial shape, pallial oviduct and geographical distribution, and includes all other littorinid species (mem-bers of genera Tectarius, Afrolittorina, Littoraria, Melarhaphe and Littorina) found in the eastern Atlantic region. Three new species are described: E. peregrinator, E. caboverdensis and E. soroziczac. One name change is proposed: Littorina lemniscata Philippi, 1846 was formerly listed as a junior synonym of E. miliaris from Ascension Island, but examination of types has shown this to be a senior synonym of E. galapagiensis (Stearns, 1892) from the tropical eastern Pacific, which should now be called E. lemniscata. Full synonymies are given for all taxa, and the taxonomic, evolutionary and ecological literature reviewed. Distribution maps are based on examination of 312 samples and on reliable literature records. These reveal close correspondence with the biogeographic division of the region into three provinces (Lusitanian; West African; St Helena and Ascension). The allopatry of sister taxa is maintained by barriers of ocean currents, river deltas and distri-bution of continental and oceanic conditions. The eight species belong to four clades (E. peregrinator; E. soroziczac; E. punctata group; E. granosa group), each of which is sister to one or more species from the western Atlantic or belongs to a clade with western Atlantic and eastern Pacific distribution. This supports trans-Atlantic dispersal from the west, esti-mated to have occurred in the Early Miocene and in the Plio-Pleistocene.
The phylogeny of the genus Echinolittorina, and phylogeography of some of its members, have previously been examined using molecular data, so that species can now be defined by a combination of phylogenetic, morphological and geographical criteria. The 26 species recognized in the Indo-West Pacific biogeographical region form a monophyletic group, here defined as the subgenus Granulilittorina Habe & Kosuge, 1966. Morphological descriptions are provided for these 26 species, including details of shell, pigmentation of headfoot, reproductive anatomy, spermatozoa, egg capsules and radulae. Diagnoses include reference to mitochondrial gene sequences (COI). A key is based on shells, tentacle pigmentation, penial shape and geographical distribution. Seven new species are described: E. marisrubri, E. omanensis, E. austrotrochoides, E. marquesensis, E. wallaceana, E. tricincta, E. philippinensis. Three name changes are proposed: E. malaccana (Philippi, 1847) and E. cecillei (Philippi, 1851) are valid names for two members of the former 'E. trochoides' group; E. biangulata (von Martens, 1897) replaces 'E. quadricincta'. Full synonymies are given for all taxa, and the taxonomic, evolutionary and ecological literature reviewed. Distribution maps are based on examination of 1701 samples and reliable literature records. The contrast between continental and oceanic distribution patterns is emphasized; one clade of five species and two additional species are shown to have an association with upwelling areas. All species are known (or predicted from protoconch size and oviduct anatomy) to have planktotrophic development, and rare extralimital records suggest a maximum open-water dispersal distance of 1000-2100 km. The most useful morphological characters for identification are the shell, penial shape and copulatory bursa in the pallial oviduct. Sister species can be morphologically similar, but are almost always entirely allopatric, so that distributional information is important for identification. Substantial intraspecific variation is present in the shell shape and sculpture of most species; where there is a pronounced geographical pattern this may have a genetic basis, but ecophenotypic effects are also implicated, e.g. by predictable associations in some species of strongly nodulose sculpture with limestone substrates and with dry habitats where growth rate may be slow. Morphological characters are superimposed on a molecular phylogeny to demonstrate the synapomorphies of clades. This is essentially a morphostatic radiation of largely allopatric species with little morphological differentiation; ecological divergence is limited to specialization to oceanic, continental or upwelling areas and to small differences in zonation level.
From 915 plankton samples taken during the years 1968-1971 in the Gulf of Naples the prosobranch veliger larvae were separated and identified. The tows taken cover the entire annual cycle and were taken at different day-times and depths down to 300 m. The collection contains 68 different larval forms, 47 of which could be identified. From the remaining 21 larval forms 13 belong to a known genus whereas 8 remain unidentified. 35 larvae are here described or identified for the first time. The descriptions chiefly deal with size, shape and sculpture of the larval shell; they are completed and illustrated by photographs taken with the scanning electron microscope. It can be stated that shape and sculpture of the larval shell are very constant in many (if not all) species. In some closely related species the features of the larval shells differ more significantly than those of the adult shells and may, therefore, be of great taxonomic value. Some remarks are given on the annual occurrence and vertical distribution, the diurnal vertical migration and the behaviour of the swimming larvae.
Uncertainty and controversy surround the geographical and ecological circumstances that create genetic differences between populations that eventually lead to reproductive isolation. Two aspects of marine organisms further complicate this situation: (1) many species possess planktonic larvae capable of great dispersal; and (2) obvious barriers to movement between populations are rare. Past studies of speciation in the sea have focussed on identifying the effects of past land barriers and on biogeographical breakpoints. However, assessing the role such undeniable barriers actually play in the initial divergence leading to reproductive isolation requires phylogenetic studies of recent radiations living in varying degrees of sympatry and allopatry to see which barriers (if any) tend to separate sister species. Here I infer phylogenetic relationship between 23 species of the marine snail Tegula using DNA sequences from two regions of the mitochondrial genome: cytochrome c oxidase I (COI) and the small ribosomal subunit (12S). These snails possess planktonic larvae with moderate dispersal capabilities and have speciated rapidly, with over 40 extant species arising since the genus first appeared in the mid-Miocene (about 15 M.Y.B.P.). Trees constructed from the COI and 12S regions (which yielded 205 and 137 phylogenetically informative sites, respectively) were robust with respect to tree-building method, bootstrapping, and the relative weightings of transitions, transversions, and gaps. Within clades where all extant species have been sampled, five of six identified sister species pairs broadly coexist on the same side of biogeographical boundaries. These data suggest strong geographical barriers to gene flow may not always be required for speciation in the sea; transient allopatry or even ecological barriers may suffice. A survey of the geographic distributions of marine radiations suggests that coastal distributions may favor the sympatry of sister taxa more than island distributions do.
1. Ten species of prosobranch gastropod veligers collected from the open waters of the North Atlantic Ocean have been identified by comparison of their larval shells with the protoconchs of identifiable juvenile or adult museum specimens. The larvae described are those of Cymatium parthenopeum (von Salis), Cymatium nicobaricum (Roding), and Charonia variegata (Lamarck) belonging to the family Cymatiidae; Tonna galea (Linne) and Tonna maculosa (Dillwyn) belonging to the family Tonnidae; Phalium granulatum (Born) belonging to the family Cassidae; Thais haemastoma (Linne), a muricid; Phil