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Molecular Analysis Of Acanthemblemaria Macrospilus (Teleostei: Chaenopsidae) With Description Of A New Species From The Gulf Of California, Mexico
Abstract
Molecular analysis of the chaenopsid tube blenny, Acanthemblemaria macrospilus Brock, reveals species-level differentiation and the existence of a new species, described here as Acanthemblemaria hastingsi, using molecular and morphological data. This new species is a member of the hancocki species group and is limited to the Gulf of California. It is distinguishable from A. macrospilus by mitochondrial gene sequences of cytochrome C oxidase I and D-loop region as well as by coloration. This differentiation is also supported to a lesser extent by the nuclear ribosomal protein S7 first intron. There is no geographic overlap in the ranges of these species, as they occur exclusively on either side of the Sinaloan Gap.
... Since the comprehensive treatment of the family Chaenopsidae by Stephens (1963), more named species have been added to Acanthemblemaria than to any other chaenopsid genus. Much of this growth has been due to the recognition that several species with broad distributions contain cryptic, often allopatric taxa (Hastings and Robertson, 1999a;Hastings and Springer, 2009a,b;Lin and Galland, 2010). ...
... In the Gulf of California, A. balanorum partially overlaps the range of the recently described sister species of A. macrospilus (A. hastingsi Lin and Galland, 2010; not included in this study). As in the A. spinosa, (A. ...
... Determining the geography of speciation for any taxonomic group is difficult because current species distributions may not reflect those at the time of speciation (Losos and Glor, 2003). In the case of Acanthemblemaria, this is exacerbated by evidence that extinction (Clarke, 1996;Eytan and Hellberg, 2010), poorly known geographic ranges (Dennis et al., 2004(Dennis et al., , 2005Hastings and Robertson, 1999b; this study), and the presence of cryptic taxa Hastings and Springer, 2009a;Lin and Galland, 2010; this study) may be common in this genus. ...
Neotropical reef fish communities are species-poor compared to those of the Indo-West Pacific. An exception to that pattern is the blenny clade Chaenopsidae, one of only three rocky and coral reef fish families largely endemic to the Neotropics. Within the chaenopsids, the genus Acanthemblemaria is the most species-rich and is characterized by elaborate spinous processes on the skull. Here we construct a species tree using five nuclear markers and compare the results to those from Bayesian and parsimony phylogenetic analyses of 60 morphological characters. The sequence-based species tree conflicted with the morphological phylogenies for Acanthemblemaria, primarily due to the convergence of a suite of characters describing the distribution of spines on the head. However, we were able to resolve some of these conflicts by performing phylogenetic analyses on suites of characters not associated with head spines. By using the species tree as a guide, we used a quantitative method to identify suites of correlated morphological characters that, together, produce the distinctive skull phenotypes found in these fishes. A time calibrated phylogeny with nearly complete taxon sampling provided divergence time estimates that recovered a mid-Miocene origin for the genus, with a temporally and geographically complex pattern of speciation both before and after the closure of the Isthmus of Panama. Some sister taxa are broadly sympatric, but many occur in allopatry. The ability to infer the geography of speciation in Acanthemblemaria is complicated by extinctions, incomplete knowledge of their present geographic ranges and by wide-spread taxa that likely represent cryptic species complexes.
... Distinct population structuring has been found over extremely short spatial scales using mitochondrial markers (Lin et al. 2009;Eytan and Hellberg 2010), and species delimitation of cryptic species using mitochondrial COI has shown large levels of sequence divergence (Victor 2010; Eytan and Hellberg 2010;Eytan et al. 2012). Multiple species of chaenopsids have shown evidence of significant allopatric population structuring; within the Gulf of California (Bernardi et al. 2003;Lin et al. 2009;Lin and Galland 2010;Riginos 2005) and the Caribbean (Eytan and Hellberg 2010). ...
Life history characteristics of cryptobenthic reef fishes (CRFs), such as their fast growth and reproductive rates, near-shore larval retention and high turnover, predispose these species to rapid diversification and cryptic speciation. This may be particularly true for isolated CRF populations. The sailfin blenny, Emblemaria pandionis, is widespread throughout the Caribbean and is found on the reefs of the Flower Garden Banks, an isolated reef system in the NW Gulf of Mexico. Using DNA barcoding and multi-locus delimitation, we show that E. pandionis is a species complex comprised of at least four distinct taxonomic units in the Caribbean, one at the Flower Garden Banks, a second in eastern Florida, a third in the central Caribbean and a fourth in Curaçao. The phylogenetic relationships within the E. pandionis species complex are defined by well-established phylogeographic barriers to gene flow in the Caribbean. Populations of E. pandionis from eastern Florida are genetically distinct from populations found in the Bahamas, highlighting the role of the Florida Strait as a strong barrier to gene flow and populations in Curaçao are deeply divergent from all other populations sampled in the Caribbean. Results from this study highlight the roles of isolated reefs and ocean currents in the speciation of cryptobenthic reef fishes.
... It has also been based on other genes and applied for situations that defy traditional morphologically-based identifications; e.g., species that share similar morphological characters (Krück et al., 2013), such as jellyfish (Prieto et al., 2013), or specimens of the larval stage (Neira and Keane, 2008; Ayala et al., 2016 ). DNA barcoding has proved a useful tool to ascertain species composition and diversity of wild fish populations as well as seafood products (Rach et al., 2008; Rasmussen and Morrissey, 2008; Janzen et al., 2009; Botti and Giuffra, 2010; Lin and Galland, 2010; Armani et al., 2015; Pappalardo and Ferrito, 2015; Tuuli et al., 2016). Therefore, applying such a method to identify species in fisheries catch can help provide critical information on composition and relative dance among exploited fishes (e.g., Neira and Keane, 2008; Botti and Giuffra, 2010; Ardura et al., 2013; Tzeng and Chiu, 2012). ...
An annotated checklist of the fish fauna associated to insular ecosystems in the Gulf of California is presented, which is composed of 615 species included in 3 classes, 37 orders, 121 families, and 338 genera. The list is based on fish collections and a critic analysis of related literature. The number of fish species associated to islands in the Gulf of California represents 67.5% of all species known for the entire Gulf (911 spp.) as well as 22.8% of the fish fauna from Mexico (2 692 spp.) and 50.3% for the Tropical Eastern Pacific (1 222 spp.). Zoogeographically, the fish species showed a higher affinity to the Sinuscalifornian (Cortez) province (71.2%), followed by the Mexican (60%), Panamic (54.8%) and Sandiegan (43.3%) provinces. Based on their distributional patterns, 10.2% of the species are endemic to the Gulf of California, 10.1% are circuntropical, 7.0% amphipacific, and 1.6% amphiamerican. Because of its great fish diversity, the insular area in the Gulf of California represents the richest insular complex in the Eastern Pacific.
The FISH-BOL campaign was initiated in 2005, and currently has barcoded for the cytochrome c oxidase subunit I (COI) gene about 8,000 of the 31,000 fish species currently recognised. This includes the great majority of the world's most important commercial species. Results thus far show that about 98% and 93% of marine and freshwater species, respectively, are barcode distinguishable. One important issue that needs to be more fully addressed in FISH-BOL concerns the initial misidentification of a small number of barcode reference specimens. This is unsurprising considering the large number of fish species, some of which are morphologically very similar and others as yet unrecognised, but constant vigilance and ongoing attention by the FISH-BOL community is required to eliminate such errors. Once the reference library has been established, barcoding enables the identification of unknown fishes at any life history stage or from their fragmentary remains. The many uses of the FISH-BOL barcode library include detecting consumer fraud, aiding fisheries management, improving ecological analyses including food web syntheses, and assisting with taxonomic revisions.
Phylogenetic relationships within tube blennies (Chaenopsinae) were reconstructed using Bayesian, maximum parsimony and likelihood analyses of multiple molecular markers (mitochondrial DNA: COI; nuclear DNA: TMO-4C4, RAG1, Rhodopsin, and Histone H3) and 148 morphological characters. This total-evidence based topology is well-resolved and congruent across analytical methods with strong support for the monophyly of the Chaenopsinae, all included genera and several internal nodes. A rapid radiation in the early evolution of chaenopsins is inferred from the relatively poor support values for relationships among basal lineages and their divergence into different habitats (rocky reefs, coral reefs and the reef/sand interface). Rates of molecular evolution in chaenopsins, as inferred by divergence among four putative transisthmian geminate species pairs, are rapid compared to other fishes. Conflicts among genetic markers and morphology are especially evident within the genus Coralliozetus, with different species relationships supported by morphology, TMO-4C4, and RAG1 plus Rhodopsin. This study hypothesizes a novel sistergroup relationship between Ekemblemaria and Hemiemblemaria, consistent with morphological, molecular and habitat use data. Our total evidence phylogenetic hypothesis indicates that previously hypothesized morphological characters supporting a close relationship between Hemiemblemaria and Chaenopsis plus Lucayablennius resulted from convergent evolution in these relatively free-swimming blennies.
Aphids in the genus Hyalopterus Koch (Hemiptera: Aphididae) are pests of stone fruit trees in the genus Prunus globally, causing damage directly through feeding as well as transmission of plant viruses. Despite their status as cosmopolitan pests, the genus is poorly understood, with current taxonomy recognizing two, likely paraphyletic, species: Hyalopterus pruni (Koch) and Hyalopterus amygdali (Blanchard). Here we present a systematic study of Hyalopterus using a molecular phylogeny derived from mitochondrial, endosymbiont, and nuclear DNA sequences (1,320 bp) and analysis of 16 morphometric characters. The data provides strong evidence for three species within Hyalopterus, which confirms previous analyses of host plant usage patterns and suggests the need for revision of this genus. We describe a new species H. persikonus Miller, Lozier & Foottit n. sp., and present diagnostic identification keys for the genus.
We present here a framework for the study of molecular variation within a single species. Information on DNA haplotype divergence is incorporated into an analysis of variance format, derived from a matrix of squared-distances among all pairs of haplotypes. This analysis of molecular variance (AMOVA) produces estimates of variance components and F-statistic analogs, designated here as phi-statistics, reflecting the correlation of haplotypic diversity at different levels of hierarchical subdivision. The method is flexible enough to accommodate several alternative input matrices, corresponding to different types of molecular data, as well as different types of evolutionary assumptions, without modifying the basic structure of the analysis. The significance of the variance components and phi-statistics is tested using a permutational approach, eliminating the normality assumption that is conventional for analysis of variance but inappropriate for molecular data. Application of AMOVA to human mitochondrial DNA haplotype data shows that population subdivisions are better resolved when some measure of molecular differences among haplotypes is introduced into the analysis. At the intraspecific level, however, the additional information provided by knowing the exact phylogenetic relations among haplotypes or by a nonlinear translation of restriction-site change into nucleotide diversity does not significantly modify the inferred population genetic structure. Monte Carlo studies show that site sampling does not fundamentally affect the significance of the molecular variance components. The AMOVA treatment is easily extended in several different directions and it constitutes a coherent and flexible framework for the statistical analysis of molecular data.
Examining the pattern of nucleotide substitution for the control region of mitochondrial DNA (mtDNA) in humans and chimpanzees, we developed a new mathematical method for estimating the number of transitional and transversional substitutions per site, as well as the total number of nucleotide substitutions. In this method, excess transitions, unequal nucleotide frequencies, and variation of substitution rate among different sites are all taken into account. Application of this method to human and chimpanzee data suggested that the transition/transversion ratio for the entire control region was approximately 15 and nearly the same for the two species. The 95% confidence interval of the age of the common ancestral mtDNA was estimated to be 80,000-480,000 years in humans and 0.57-2.72 Myr in common chimpanzees.
CLUSTAL X is a new windows interface for the widely-used progressive multiple sequence alignment program CLUSTAL W. The new
system is easy to use, providing an integrated system for performing multiple sequence and profile alignments and analysing
the results. CLUSTAL X displays the sequence alignment in a window on the screen. A versatile sequence colouring scheme allows
the user to highlight conserved features in the alignment. Pull-down menus provide all the options required for traditional
multiple sequence and profile alignment. New features include: the ability to cut-and-paste sequences to change the order
of the alignment, selection of a subset of the sequences to be realigned, and selection of a sub-range of the alignment to
be realigned and inserted back into the original alignment. Alignment quality analysis can be performed and low-scoring segments
or exceptional residues can be highlighted. Quality analysis and realignment of selected residue ranges provide the user with
a powerful tool to improve and refine difficult alignments and to trap errors in input sequences. CLUSTAL X has been compiled
on SUN Solaris, IRIX5.3 on Silicon Graphics, Digital UNIX on DECstations, Microsoft Windows (32 bit) for PCs, Linux ELF for
x86 PCs, and Macintosh PowerMac.
MrBayes 3 performs Bayesian phylogenetic analysis combining information from different data partitions or subsets evolving under different stochastic evolutionary models. This allows the user to analyze heterogeneous data sets consisting of different data types—e.g. morphological, nucleotide, and protein—and to explore a wide variety of structured models mixing partition-unique and shared parameters. The program employs MPI to parallelize Metropolis coupling on Macintosh or UNIX clusters.
Availability: http://morphbank.ebc.uu.se/mrbayes
Contact: fredrik.ronquist@ebc.uu.se
*
To whom correspondence should be addressed.
Two hundred and seven species of fish, mostly Australian marine fish, were sequenced (barcoded) for a 655 bp region of the mitochondrial cytochrome oxidase subunit I gene (cox1). Most species were represented by multiple specimens, and 754 sequences were generated. The GC content of the 143 species of teleosts was higher than the 61 species of sharks and rays (47.1% versus 42.2%), largely due to a higher GC content of codon position 3 in the former (41.1% versus 29.9%). Rays had higher GC than sharks (44.7% versus 41.0%), again largely due to higher GC in the 3rd codon position in the former (36.3% versus 26.8%). Average within-species, genus, family, order and class Kimura two parameter (K2P) distances were 0.39%, 9.93%, 15.46%, 22.18% and 23.27%, respectively. All species could be differentiated by their cox1 sequence, although single individuals of each of two species had haplotypes characteristic of a congener. Although DNA barcoding aims to develop species identification systems, some phylogenetic signal was apparent in the data. In the neighbour-joining tree for all 754 sequences, four major clusters were apparent: chimaerids, rays, sharks and teleosts. Species within genera invariably clustered, and generally so did genera within families. Three taxonomic groups-dogfishes of the genus Squalus, flatheads of the family Platycephalidae, and tunas of the genus Thunnus-were examined more closely. The clades revealed after bootstrapping generally corresponded well with expectations. Individuals from operational taxonomic units designated as Squalus species B through F formed individual clades, supporting morphological evidence for each of these being separate species. We conclude that cox1 sequencing, or 'barcoding', can be used to identify fish species.
A number of methods have been proposed for addressing how to optimize the analysis of multiple data sets from diverse mitochondrial and nuclear gene partitions in the pursuit of robust organismal phylogenies. The present study used separate, simultaneous, and conditional data combination methods to analyze 3,135 bp of data from four mitochondrial partitions and the seventh intron of the beta fibrinogen gene in the Asian pit viper genus, Trimeresurus sensu stricto. The phylogenetic utility and homogeneity of all partitions were estimated via a combination of homogeneity partition tests, homoplasy indices, and partitioned Bremer support. Despite the detection of significant heterogeneity of phylogenetic signal between the mitochondrial and nuclear partitions, the simultaneous analysis represented the best-supported topology of all the data. The relatively slow rate (approximately one quarter of the rate of mtDNA) and functionally unconstrained molecular evolution of the intron resulted in much lower levels of homoplasy compared with the mitochondrial partitions. This was further shown via partitioned Bremer support, which, when considered throughout hierarchical clade levels, highlighted the phylogenetic strength and limitations of the intron at deeper and shallower phylogenetic levels, respectively. The simultaneous analysis helped to resolve the phylogenetic relationships of taxa that were unresolved throughout all individual gene trees and tentatively supports the existence of morphologically and genetically distinct clades within the genus. Topological appraisals of the mitochondrial gene partitions suggest that the cytochrome b and the NADH subunit 4 gene partitions are better estimators of phylogenetic relationships than are the 12S and 16S ribosomal RNA partitions at the taxonomic levels under consideration.
We announce the release of the fourth version of MEGA software, which expands on the existing facilities for editing DNA sequence data from autosequencers, mining Web-databases, performing automatic and manual sequence alignment, analyzing sequence alignments to estimate evolutionary distances, inferring phylogenetic trees, and testing evolutionary hypotheses. Version 4 includes a unique facility to generate captions, written in figure legend format, in order to provide natural language descriptions of the models and methods used in the analyses. This facility aims to promote a better understanding of the underlying assumptions used in analyses, and of the results generated. Another new feature is the Maximum Composite Likelihood (MCL) method for estimating evolutionary distances between all pairs of sequences simultaneously, with and without incorporating rate variation among sites and substitution pattern heterogeneities among lineages. This MCL method also can be used to estimate transition/transversion bias and nucleotide substitution pattern without knowledge of the phylogenetic tree. This new version is a native 32-bit Windows application with multi-threading and multi-user supports, and it is also available to run in a Linux desktop environment (via the Wine compatibility layer) and on Intel-based Macintosh computers under the Parallels program. The current version of MEGA is available free of charge at (http://www.megasoftware.net).
A new member of the "hancocki" species complex, Acanthemblemaria castroi, is described from the Galapagos Islands. A new species, Coralliozetus springeri, is described from the Pacific coast of Panama, forming a geminate pair with C. cardonae from the Caribbean Sea. The description of the latter species is supplemented as is that of Chaenopsis schmitti Böhlke. The ranges of three species are extended: Coralliozetus boehlkei Stephens to Cocos Island, Coralliozetus angelica (Böhlke and Mead) to Socorro Island, the Revillagigedos, and Acanthemblemaria balanorum Brock to Bahia Piñas, Panama. Meristic variation with latitude, size reduction in the Cocos Island population, and reproductive behavior are described for Acanthemblemaria macrospilus Brock.
A parsimony analysis of the relationships of Acanthemblemaria species was conducted based on 60 morphological characters. Outgroups included the two species of Ekemblemaria, the apparent sister group of Acanthemblemaria, and a hypothetical outgroup based on character state distributions within potential second outgroups. The monophyly of Acanthemblemaria, containing 17 species, is supported by 5 synapomorphies: a fleshy or ossified process on the nasal bone adjacent to the first anterofrontal pore, spines on the raised ridges of the frontals, serrations or spines on the orbital margin of the frontal, serrations or spines on the orbital margin of the lateral ethmoid, and two rows of palatine teeth. Three equally parsimonious trees were found, and a strict consensus tree revealed that relationships were fully resolved except within a portion of the "hancocki species group" (Fig. 1). Species groups recognized by recent workers were supported and species relationships proved to be highly nested. The two species of Ekemblemaria and two species pairs of Acanthemblemaria follow the eastern Pacific-Caribbean distributional track, with one of the latter indicating a rarely reported relationship between the southern Caribbean and the Galapagos Islands.
The utilization of the spatial resources of refuge type, size and depth placement is investigated in the three sympatric species of Acanthemblemaria at the cape region of Baja California, Mexico. A. balanorum occupies barnacle testes (Balanus tintinnabulum), A. macrospilus occupies barnacles and mollusk tubes (vermetid gastropods and pholadids), and A. crockeri occupies only mollusk tubes (pholadids). Refuge diameter overlap is higher than overlap in depth. A. crockeri consistently occupies depths below 5m. Competition experiments for barnacle refuges among the three species indicate that A. balanorum is a superior competitor for such refuges. Prior residency of a less superior species changes the outcome of refuge competition in its favor. The morphological specialization of A. balanorum and A. macrospilus is evident in a high correlation between head size and standard length. A. balanorum selects refuges with entrance diameters highly correlated to standard length.
The Tropical Eastern Pacific Biogeographic Region (TEP) is delimited by steep thermal gradients to the north and south, by a wide expanse of open ocean (the East Pacific Barrier) to the west, and by the Central American land mass to the east. Four provinces within the TEP have been recognized based on the distribution of rocky shore fishes and marine invertebrates: the Cortez, Mexican, Panamic, and Galápagos Provinces. For rocky shore fishes, hypothesized barriers between these provinces are areas lacking rocky outcroppings, specifically the Central American Gap between the Panamic and Mexican Provinces, the Sinaloan Gap between the Mexican and Cortez Provinces, and the Pelagic Gap between the mainland and the Islas Galápagos. The occurrence of 33 chaenopsid fish species within these provinces, as well as other oceanic islands or archipelagos in the TEP (Isla de Malpelo, Isla del Coco, and Islas Revillagigedo) were tallied based on literature records and observations of museum specimens. Chaenopsid distributions within the TEP support these hypothesized provinces and their intervening gaps. Twenty-one species (64% of the TEP chaenopsid fauna) are restricted to a single mainland province or one of the oceanic islands or archipelagos. Of the mainland provinces, the Cortez and Panamic exhibit similar levels of endemism (50%), but the Mexican Province has only one endemic (10%). Of the remaining chaenopsids in the Mexican Province, three are widespread, occurring in all three mainland provinces, four are shared only with the Cortez Province, and two are shared only with the Panamic Province. Within the TEP, the Pelagic Gap is the most effective (crossed by only 3 of 33 species adjacent to it), followed by the Central American Gap (crossed by 5 of 21 species), and the Sinaloan Gap (crossed by 7 of 17 species). Only one species, Chaenopsis alepidota, which is found off southern California and in the Cortez Province, crosses a barrier delimiting the TEP. Species-level phylogenetic hypotheses for the Chaenopsidae imply exclusively allopatric speciation for these fishes in the TEP. Of the barriers delimiting the TEP, the most important in the recent evolution of chaenopsids is the Isthmian Barrier which is implicated in six speciation events. Within the TEP, the Central American Gap and Sinaloan Gap are each implicated in three speciation events, while the Pelagic Gap is implicated in three speciation events of island endemics from mainland populations and one inter-island speciation event.
The diets of three syntopic Gulf of California Acanthemblemaria (A. balanorum, A. crock-eri and A. macrospilus) and A. castroi from the Galapagos Island are nearly uniformly composed of harpacticoid copepods and other small benthic-vagile or planktonic crustaceans. On occasion, large prey items such as crabs or other small fishes are taken. HORN'S index of niche overlap indicates that the three syntopic Acanthemblemaria are not separated along the food resource utilization axis. Slight variations in diets among the syntopic species seem to be related to differences in degree of microhabitat specialization.
We present here a new version of the Arlequin program available under three different forms: a Windows graphical version (Winarl35), a console version of Arlequin (arlecore), and a specific console version to compute summary statistics (arlsumstat). The command-line versions run under both Linux and Windows. The main innovations of the new version include enhanced outputs in XML format, the possibility to embed graphics displaying computation results directly into output files, and the implementation of a new method to detect loci under selection from genome scans. Command-line versions are designed to handle large series of files, and arlsumstat can be used to generate summary statistics from simulated data sets within an Approximate Bayesian Computation framework.
The Gulf of California endemic reef fish, Acanthemblemaria crockeri (Blennioidei, Chaenopsidae), reportedly has two colour morphs, one with melanic lateral spots ('Gulf' morph) and one with orange spots ('Cape' morph). In this study, we recorded colour morph in both males and females and collected mitochondrial DNA sequence data for cytochrome c oxidase I (COI) and tRNA-Pro/D-loop of specimens from throughout the Gulf to explore the genetic basis of the colour morphs. Two highly divergent (HKY + I distance = 11.9% for COI), reciprocally monophyletic lineages were identified, consistent with the presence of two parapatric species. A 30-km gap between the distributions of mitochondrial lineages roughly corresponds to a hypothesized former seaway across the Baja California peninsula north of La Paz, although the estimated divergence time (1.84 million years ago) is more recent than the hypothetical seaway (3-4 million years ago). Surprisingly, the distribution of mitochondrial species is not congruent with the distribution of either male or female colour morphs. Our analysis also revealed significant population differentiation within both species and no shared haplotypes among populations. The northern Gulf species includes four populations (NB, CB, NM and CM) corresponding to northern and central Baja and northern and central mainland sites, while the Cape species includes two populations (SB and SM) corresponding to the Baja and mainland sides of the southern Gulf. The NB/CB division corresponds to a hypothesized Plio-Pleistocene mid-peninsular seaway. The level of genetic divergence documented in this lineage is extraordinary for a marine fish with a pelagic larval stage within a semi-enclosed basin.
Clinus cottoides is a fish endemic to the coast of South Africa, predominantly inhabiting rock pools. All South African clinids are viviparous, but probably breed throughout the year; as such, their dispersal may be limited, unlike species with pelagic larval stages. We analysed 343 fish from 14 localities on the west, south and east coasts using two mitochondrial genes and the second intron of the S7 ribosomal gene. Mitochondrial DNA analyses recovered significant genetic differentiation between fish populations from the east coast and other sampling locations, with a second break found between Gansbaai and Cape Agulhas on the south coast. Nuclear DNA recovered shallower, but significant, levels of population structure. Coalescent analyses suggested remarkably asymmetrical gene flow between sampling locations, suggesting that the cold Atlantic Benguela Current and Indian Ocean Agulhas counter-current play important roles in facilitating dispersal. There was no gene flow between the east coast and the other sites, suggesting that these populations are effectively isolated. Divergence times between them were estimated to at least 68 000 years. Neutrality tests and mismatch distributions suggest recent population expansions, with the exception of peripheral western and eastern populations (possibly a consequence of environmental extremes at the edge of the species distribution). Analyses of the current South African marine protected areas network show that it is not connected and that De Hoop, one of South Africa's largest marine reserves, appears to be an important source population of recruits to both the south and southwest coasts.
We amplified and sequenced the mitochondrial control region from 23 species representing six families of teleost fish. The length of this segment is highly variable among even closely related species due to the presence of tandemly repeated sequences and large insertions. The position of the repetitive sequences suggests that they arise during replication both near the origin of replication and at the site of termination of the D-loop strand. Many of the conserved sequence blocks (CSBs) observed in mammals are also found among fish. In particular, the mammalian CSB-D is present in all of the fish species studied. Study of potential secondary structures of RNAs from the conserved regions provides little insight into the functional constraints on these regions. The variable structure of these control regions suggests that particular care should be taken to identify the most appropriate segment for studies of intraspecific variation.
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Atlantic fishes of the genus Acanthemblemaria, with description of three new species and comments on Pacific species (Clinidae: Chaenopsinae)
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