[Show abstract][Hide abstract] ABSTRACT: Our understanding of the effect of Pleistocene climatic changes on the biodiversity of European mammals mostly comes from phylogeographical studies of non-subterranean mammals, whereas the influence of glaciation cycles on subterranean mammals has received little attention. The lack of data raises the question of how and to what extent the current amount and distribution of genetic variation in subterranean mammals is the result of Pleistocene range contractions/expansions. The common mole (Talpa europaea) is a strictly subterranean mammal, widespread across Europe, and represents one of the best candidates for studying the influence of Quaternary climatic oscillation on subterranean mammals. Cytochrome b sequences, as obtained from a sampling covering the majority of the distribution area, were used to evaluate whether Pleistocene climate change influenced the evolution of T. europaea and left a trace in the genetic diversity comparable to that observed in non-subterranean small mammals. Subsequently, we investigated the occurrence of glacial refugia by comparing the results of phylogeographical analysis with species distribution modelling. We found three differentiated mitochondrial DNA lineages: two restricted to Spain and Italy and a third that was widespread across Europe. Phylogenetic inferences and the molecular clock suggest that the Spanish moles represent a highly divergent and ancient lineage, highlighting for the first time the paraphyly of T. europaea. Furthermore, our analyses suggest that the genetic break between the Italian and the European lineages predates the last glacial phase. Historical demography and spatial principal component analysis further suggest that the Last Glacial Maximum left a signature both in the Italian and in the European lineages. Genetic data combined with species distribution models support the presence of at least three putative glacial refugia in southern Europe (France, Balkan Peninsula and Black Sea) during the
Biological Journal of the Linnean Society 02/2015; 114(3):495-512. DOI:10.1111/bij.12459 · 2.26 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The black rat Rattus rattus is recognized as one of the world’s most harmful invasive species. It has spread across the globe by passive human transport and the dynamics of colonization have been investigated in several areas of the world. However, data for the Mediterranean basin are still lacking. We investigated the black rat colonization of the western Mediterranean basin by means of mitochondrial genes. Mitochondrial control region and cytochrome b gene were sequenced in order to quantify genetic diversity of western Mediterranean black rats. Maximum likelihood phylogenetic analysis based on cytochrome b was used to assign specimens to a specific lineage of the R. rattus species complex. The mitochondrial control region was used to reconstruct phylogeographic pattern by statistical parsimony network and to asses historical demography of western Mediterranean black rats. The results show an unexpectedly low diversity considering that the Mediterranean basin has been a trade route since very ancient times. The results mtDNA analysis are compatible with a single event of invasions of western Mediterranean by R. rattus.
[Show abstract][Hide abstract] ABSTRACT: The clouded anole Anolis nebulosus (Squamata: Polychrotidae) is widespread on the Pacific coast of Mexico. The species also inhabits Don Panchito, a small islet located near the coast of the Chamela-Cuixmala Biosphere Reserve in the state of Jalisco. We studied the extent of intraspecific differences in morphology (absolute size and body proportions) and in mtDNA sequences (16S and NDH2) between the population living on the islet (N = 18 for morphometry; N = 12 for mtDNA) and the one on the facing mainland (N = 38 for morphometry; N = 16 for mtDNA). The individuals on the islet are larger than those on the mainland with little overlap in size for either males (islet: 52.79 ± 1.82 mm; mainland: 40.96 ± 2.99 mm) or females (islet: 46.18 ± 3.24 mm; mainland 37.14 ± 2.13 mm). The presence of insular gigantism, as here found in A. nebulosus, seems uncommon in the genus and could be explained as a combination of low predation pressure and higher intraspecific competition on the island. Moreover, we found that sexual dimorphism (SD) is higher in the island population than in the mainland one. The molecular analysis shows the absence of shared haplotypes between the island and mainland populations. Ten mtDNA haplotypes belonged to the mainland population and three to the island population. The shape of the minimum spanning network and of the mismatch distribution indicates a single colonization event. These molecular data indicate a certain degree of isolation of the island population notwithstanding its proximity to the coast. The morphological characteristics of the anoles on Don Panchito match with the expectation of the so-called “reversed island syndrome” theory, which predicts an increased body size and sexual dimorphism in lizards living on very small islands characterized by unpredictable environmental conditions.
[Show abstract][Hide abstract] ABSTRACT: Standard karyotypes of two species of the genus Scincella, S. assata and S. cherriei, both from Chiapas State, Mexico, were described for the first time. The diploid chromosome number was 28 in S. assata, whereas 30 in S. cherriei. The karyotypes of the two species, while differing in the number of microchromosomes, 14-15 in S. assata and 16-17 in S. cherriei, share four pairs of large metacentric, two pairs of medium-sized metacentric, and one particular pair (number 7) of chromosomes. Female S. assata carries chromosome pair 7 composed of two identical medium-sized subtelocentric chromosomes. This chromosome pair is heteromorphic in males of both species, i.e., one com-ponent of the pair is similar to the homomorphic chromosomes 7 of the S. assata female, while the other is nearly one-half the size of its counterpart and resembles a microchromosome. The homology of such externally different elements is deducted from the presence of an asymmetric bivalent in spermatocytes at diplotene-diakinesis. Female S. cherriei was not available. We suspect that the two Scincella species possess an XY sex determination system, as previously reported for the North American congeneric species, S. lateralis.
[Show abstract][Hide abstract] ABSTRACT: The karyotype of a sphaerodactylid gecko Euleptes europaea (Gené, 1839) was assembled for the first time in this species. It is made of 2n = 42 gradually decreasing in size chromosomes, the highest chromosome number so far acknowledged in the family Sphaerodactylidae. The second chromosome pair of the karyotype appears slightly heteromorphic in the male individual. Accordingly, FISH with a telomeric probe revealed an uneven distribution of telomeric repeats on the two homologues of this pair, which may be indicative of an XY sex-determination system in the species, to be further investigated.
[Show abstract][Hide abstract] ABSTRACT: The Italian Peninsula was one of the main refugia in southern Europe during the climatic oscillations of the Pleistocene, and was considered a ‘hotspot’ of biodiversity. A number of phylogeographic analyses identified highly divergent lineages in Italy that apparently did not contribute to the post-glacial re-colonization of Europe, supporting the existence of refugia within refugia in the southern-most part of Italy. For the bank vole Myodes glareolus, genetic analyses highlighted a low variability for this species on the Italian peninsula, suggesting that cryptic refugia of central Europe were the main source of postglacial re-colonization in Europe.
In this work, we analysed the mtDNA phylogeography of M. glareolus with a special emphasis on the Italian refugium. We extended previous analyses by including new sequences from a wider range of samples across the Italian peninsula. Our results suggest a high mitochondrial diversity of the bank vole in Italy and support the existence of an ancient and deeply divergent population in the Calabria region. This population did not participate to the recent re-colonization of Italy while we highlight the possible occurrence of multiple and more recent colonization events between Europe and Italy. The phylogeographic pattern observed in Italy appears compatible with refugia-within-refugia scenario.
Journal of Zoology 05/2012; 287:41-52. DOI:10.1111/j.1469-7998.2011.00884.x · 1.88 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The African genus Lygodactylus Gray, is composed of roughly 60 spe-cies of diurnal geckos that inhabit tropical and temperate Africa, Madagascar, and South America. In this study, we assessed the phylogenetic position of L. angularis, for which molecular data were so far lacking, by means of sequence analysis of the mitochondrial 16S rDNA gene. We also compared intraspecific vs. interspecific genet-ic divergences using an extended data set (34 species, 153 sequences), to determine whether a fragment of this gene can be useful for species identification and to reveal the possible existence of new cryptic species in the genus. The analysis placed L. angu-laris in a monophyletic group together with members of "fischeri" and "picturatus" groups. Nevertheless, the independence of the "angularis" lineage is supported by the high genetic divergence. Comparison of intraspecific vs. interspecific genetic dis-tances highlights that, assuming an equal molecular rate of evolution among the stud-ied species for the used gene, the threshold value useful for recognising a candidate new species can be tentatively placed at 7%. We identified four species that showed an intraspecific divergence higher than, or close to, the 7% threshold: L. capensis (8.7%), L. gutturalis (9.3%), L. madagascariensis (6.5%) and L. picturatus (8.1%). Moreover, two species, L. mombasicus and L. verticillatus, are paraphyletic in terms of gene gene-alogy. Thus, the study shows that a short fragment of the 16S rDNA gene can be an informative tool for species-level taxonomy in the genus Lygodactylus.
[Show abstract][Hide abstract] ABSTRACT: Tropical dry forests contribute to a substantial proportion of the herpetological diversity of Mexico. The south-western coast of Jalisco is one of the more important areas by number of endemics and the high presence of endangered and restricted species. In this paper we used a combined karyological and molecular genetic (sequences of mtDNA genes for NDH2, cytb or 16S rDNA) approach to genetically characterize 13 lizard species belonging to seven families that inhabit the dry forests of the Chamela-Cuixmala Biosphere Reserve (Anguidae: Gerrhonotus cf. liocephalus; Eublepharidae: Coleonyx elegans; Phyllodactylidae: Phyllodactylus lanei; Gekkonidae: Hemidactylus frenatus; Phrynosomatidae: Sceloporus melanorhinus, S. utiformis, Urosaurus bicarinatus; Polychrotidae: Norops nebulosus; Scincidae: Mabuya unimarginata, Plestiodon parvulus; Teiidae: Ameiva undulata, Aspidoscelis communis, A. lineattissima). The karyotypes of six species were here described for the first time (G. liocephalus, 2n = 38, 14 macrochromosomes and 24 microcromosomes; C. elegans, 2n = 24 FN = 26; N. nebulosus 2n = 30, 13 macro-and 17 microchromosomes; M. unimarginata 2n = 32, 18 macro-and 14 microchromosomes; P. parvulus 2n = 26, 12 macro-and 14 microchromosomes; A. undulata 2n = 50, 26 macro-and 24 microchromosomes). Chromosomal heteromorphism was found in C. elegans, N. nebulosus, and S. melanorhinus. For P. lanei we found a karyotype different from that previously described in other localities. This variation matched with a high genetic divergence usually found in different species. The DNA typing of mtDNA genes allowed the identification of the taxonomic affinities of five Mexican endemic species, namely: U. bicarinatus, A. nebulosus, P. parvulus, A. lineattissima and A. communis. The specimen of Gerrhonotus from Chamela is very divergent by 16S rDNA and probably does not belong to the so far studied species of Gerrhonotus. High genetic divergence has been also observed between samples of A. undulata and U. bicarinatus from different regions. In these latter two cases, additional data are needed to understand the taxonomic status of these populations.
[Show abstract][Hide abstract] ABSTRACT: The range of the genus Talpa covers almost all Europe up to Western Asia. This genus has never been the object of comprehensive systematic studies using molecular and genetic techniques, such that the evolutionary relationships among species remain unclear. Talpa shows high levels of endemism, and the influence of past glaciation cycles on the distribution pattern of several species has been hypothesized. In this work, we assessed the molecular systematics of the genus using the mitochondrial gene cytochrome b from eight of the nine extant species of Talpa moles. Furthermore, molecular clock estimations were used to hypothesize a biogeographic scenario in concordance with fossil data. Results suggest a monophyletic origin of the genus and a common ancestor for the western European moles T. europaea, T. caeca, T. romana and T. occidentalis. The eastern species T. altaica and T. caucasica are basally divergent. The estimated ages of divergence among lineages are in accordance with a Miocene origin of the extant moles. The genus likely originated in Asia, spreading into Europe during the Pliocene. The evolution of moles appears to have been driven by changes in moisture levels that influenced extinction and speciation events during the Miocene and the Pliocene. Pleistocene climatic oscillations likely caused the range shrinkages and expansions that led to the current distribution pattern of most Talpa species.
[Show abstract][Hide abstract] ABSTRACT: Factors affecting the distribution of species in fragmented landscapes, and their relative importance, are often unclear. Few studies have deliberately compared various hypotheses in relatively controlled conditions. Moreover, most studies to date have not incorporated false absences in their modeling. Following a multiple hypotheses testing framework, we tested the relative role of landscape structure, patch and neighborhood configuration, patch internal structure, presence or absence of predators, and presence or absence and abundance of potential competitor species on the occupancy patterns of three rodent species (Myodes glareolus (Schreber, 1780), Apodemus flavicollis (Melchior, 1834), Apodemus sylvaticus (L., 1758)) in a highly fragmented landscape in Tuscany, central Italy. Distribution patterns and occupancy dynamics of the three rodent species were affected by patch and patch neighborhood characteristics, as well as the vicinity of other patches occupied by the species. However, we found no relevant effect of the surrounding landscape structure, patch internal structure, predator patch use, and abundance or distribution of potential competitor species. The observed spatial correlation between populations and the evidence of colonization or extinction events suggest that a metapopulation approach could provide a good framework for understanding the long-term dynamics of these populations.
Canadian Journal of Zoology 08/2009; 87(8-8):662-670. DOI:10.1139/Z09-054 · 1.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The European snow vole Chionomys nivalis has a patchy distribution restricted to rocky habitats across southern Europe and the Near and Middle East. We carried out a phylogeographic study to provide a biogeographic scenario, based on molecular data, outlining the major processes that determined the current distribution of the species. The samples include 26 snow voles from 14 different populations across the entire species range from Spain to Anatolia and Israel. Nearly complete sequences (1037 bp) of the mitochondrial gene for cytochrome b were sequenced. Relationships among haplotypes were inferred with neighbour-joining, maximum likelihood, maximum parsimony analyses and minimum spanning network. An analysis of mismatch distribution was used to cast light on past demographic expansion. We found 22 different haplotypes that fall into six distinct lineages, all but one is supported by high bootstrap values with all methods. Four lineages are allopatric (Tatra Mts., Iberia, Balkans and Middle East) while divergent haplotypes from two lineages show sympatry in the Alps and the Apennines. The basal relationships of these lineages could not be established by any tree. The mean pairwise genetic distance between lineages ranges from 2.4 to 4.2%. The shape of the mismatch distribution indicated a past expansion event dating back to between 158 000 and 84 000 years ago. These data can be interpreted with the existence of southern glacial refugia (Iberia, Balkans, Middle East and Italy) and one additional northern glacial refugium. The lack of phylogenetic resolution among lineages and the shape of mismatch distribution are indicative of a simultaneous and rapid splitting due to a relatively fast initial expansion of populations. Moreover, the analysis supports the hypothesis of the European origin of C. nivalis and its subsequent eastward dispersion during the Middle Pleistocene.
[Show abstract][Hide abstract] ABSTRACT: The genus Crocidura Wagler, 1832 represents the most diverse group of Soricidae. It is widely accepted that the genus is in need of revision, because the taxonomy of several species is still unresolved. In this paper, we present a chromosomal (standard and G-banding) and molecular genetic (16S rDNA, 1112bp; cytochrome b, 501bp) characterization of specimens of Crocidura luna from Zambia. We compare these data with those obtained for the same species from Burundi. The genetic divergence (uncorrected p-distance) between the two samples is 4.1% for cytochrome b and 1.1% for 16S. These values are usually found among close sister species or different populations of the same species in Crocidura. The karyotype found in C. luna (2ns28 and FN=56) is of particular interest, as it represents one of the lowest diploid numbers among the genus Crocidura. Moreover, it presents large chromosomal differences compared to the karyotype of C. luna, previously described in the specimens from Burundi with 2n=36 and NF=56.
[Show abstract][Hide abstract] ABSTRACT: This paper describes a study of the 5S ribosomal RNA genes (5S rDNA) in a group of 6 species belonging to 4 genera of Mugilidae. In these 6 species, the relatively short 5S rDNA repeat units, generated by PCR and ranging in size from 219 to 257 bp, show a high level of intragenomic homogeneity of both coding and spacer regions (NTS-I). Phylogenetic reconstructions based on this data set highlight the greater phylogenetic and genetic diversity of Mugil cephalus and Oedalechilus labeo compared with the genera Liza and Chelon. Comparative sequence analysis revealed significant conservation of the short 5S rDNA repeat units across Chelon and Liza. Moreover, a second size class of 5S rDNA repeat units, ranging from roughly 800 to 1100 bp, was produced in the Liza and Chelon samples. Only short 5S rDNA repeat units were found in M. cephalus and O. labeo. The sequences of the long 5S rDNA repeat units, obtained in Chelon labrosus and Liza ramada, differ owing to the presence of 2 large insertion/deletions (indels) in the spacers (NTS-II) and show considerable sequence identity with NTS-I spacers. Interspecific sequence variation of NTS-II spacers, excluding the indels, is low. Southern-blot hybridization patterns suggest an intermixed arrangement of short and long repeat units within a single chromosome locus.
[Show abstract][Hide abstract] ABSTRACT: We studied the intraspecific genetic variation of 17 Neomys anomalus (Cabrera, 1907) (eight localities) and 24 Neomys fodiens (Pennant, 1771) (nine localities) in Europe. As molecular marker, we used the sequences of the mtDNA gene for cytochrome b (1140 bp from 24 specimens; 272 bp from 15 specimens). The phylogenetic analysis of N. fodiens shows slight divergence among haplotypes, with only one supported clade including two geographically distant haplotypes from Calabria (southern Italy) and Pyrenees (France); these haplotypes diverge from the others by 2.9% and 2.1%, respectively. In N. anomalus, one haplotype from Spain is very different, diverging from all others by 8-10% of the sequence. This level of divergence is similar to that found between N. anomalus and another species, Neomys teres. There are two other supported clades in N. anomalus, an Italian subclade and an eastern subclade comprising haplotypes from Turkey and Slovenia. Moreover, we found a different genetic structure between the two species with greater divergence in N. anomalus than in N. fodiens. The phylogeographic patterns are discussed in a temporal framework and considering the different ecological characteristics of these two species.
Journal of Zoological Systematics and Evolutionary Research 03/2007; 45(3):255 - 262. DOI:10.1111/j.1439-0469.2006.00391.x · 1.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The European representatives of the subfamily Talpinae belong to the monophyletic genus Talpa. Five out of the nine species of Talpa occur in Western Europe. A wide central area is occupied by Talpa europaea, while the small sized Talpa caeca occurs in southern Europe. Three endemic species are restricted to the peripheral areas of the genus range and show a parapatric distribution with respect to T. europaea, i.e. the Iberian T. occidentalis, the southern Italian T. romana and the Balkan T. stankovici. The karyotypes of moles are very conservative, with the majority of the species showing 2n = 34. Allozyme data first allowed to assess the specific status of endemic taxa and the low levels of heterozygosity. Nei's genetic distances suggest that T. occidentalis, T. romana and T. stankovici early diverged from an europaea–caeca line. Preliminary results from mtDNA analyses strongly support the monophyly of Western European moles, but are still not able to solve the relationships within this clade. Estimates of time of divergences indicate a basal split of an Eastern and a Western lineage during the Miocene-Pliocene transition, while the divergence among the Western European moles should have occurred in association to the Pliocene-Pleistocene climatic oscillations.
Mammal Study 12/2005; 30(sp1):13-17. DOI:10.3106/1348-6160(2005)30[S13:OAEOWE]2.0.CO;2 · 0.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The African gerbils of the genus Tatera are widespread and abundant throughout sub-Saharan Africa. There is still today a certain controversy concerning the taxonomy of these rodents and very few attempts have been made to assess their systematic relationships. The present paper introduces findings based on the partial sequences of cytochrome b (495 bp) and the 16S rRNA (469 bp) mitochondrial genes of six (T. robusta, T. nigricauda, T. vicina, T. leucogaster, T. valida, and T. kempi) species together with two additional taxa. We also report the karyotypes of T. vicina and T. leucogaster. We propose that T. vicina should be considered as a valid species and show the monophyly of the robusta species group, with the exclusion of T. leucogaster. Our results show there is a different chromosomal evolutionary pattern within the two major lineages, which is recognizable through molecular phylogenetics. One is characterized by karyotype stability and the other by a considerable number of chromosomal rearrangements. The lineage divergence coincides with the formation of the East African Rift. The processes that led to the origin of the East African species seem to be related to the subsequent climatic changes, which caused cyclic contraction and expansion of the savannah biomes. Furthermore, geological activities that characterized East Africa during Plio-Pleistocene may also have contributed to lineage divergence.