Petros Lymberakis

Molecular phylogeny and biogeography of the wall-lizard Podarcis erhardii (Squamata: Lacertidae).

Erhards wall lizard, Podarcis erhardii (Sauria: Lacertidae), is highly diversified in Greece and especially in the southern Aegean region. Out of the 28 recognized subspecies, 27 are found in Greece from the North Sporades island-complex in the North Aegean (grossly south of the 39th parallel) to the island of Crete in the South. The species exhibits great morphological and ecological plasticity and inhabits many different habitats from rocky islets and sandy shores to mountaintops as high as 2000m. By examining intraspecific variability at a segment of the mitochondrial gene cytochrome b we have found that that extant populations of P. erhardii are paraphyletic. Furthermore, we have found that subspecies previously defined on the basis of morphological characteristics do not correspond to different molecular phylogenetic clades, so that their status should be reconsidered. The DNA based biogeographical and phylogenetic history of Podarcis in Southern Greece is congruent with available paleogeographic data of the region, which supports the view that DNA sequences may be a useful tool for the study of palaeogeography.

Phylogeography of Balkan wall lizard (Podarcis taurica) and its relatives inferred from mitochondrial DNA sequences

Wall lizards of the genus Podarcis (Sauria, Lacertidae) comprise 17 currently recognized species in southern Europe, where they are the predominant reptile group. The taxonomy of Podarcis is complex and unstable. Based on DNA sequence data the species of Podarcis falls into four main groups that have substantial geographical conherence (western island group, southwestern group, Italian group and Balkan group). The Balkan species are divided in two subgroups: the subgroup of Podarcis taurica (P. taurica, P. milensis, P. gaigeae and perhaps P. melisellensis), and the subgroup of Podarcis erhardii (P. erhardii and P. peloponnesiaca). We addressed the question of phylogenetic relations among the species of the P. taurica subgroup encountered in Greece, as they can be inferred from partial mtDNA (cyt b and 16S) sequences. Our data support the monophyly of P. taurica subgroup and suggest that P. gaigeae, P. milensis and P. melisellensis form a clade, which thereinafter connects to P. taurica. Within the previous clade, P. gaigeae is more closely related to P. milensis than to P. melisellensis. However, the specimens of P. taurica were subdivided in two different groups. The first one includes the specimens from northeastern Greece, and the other group includes the specimens from the rest of continental Greece and Ionian islands. Because the molecular clock of the cyt b and 16 rRNA genes was not rejected in our model test, it is possible to estimate times of speciation events. Based on the splitting of the island of Crete from Peloponnisos [c. 5 million years ago (Ma)], the evolutionary rate for the cyt b is 1.55% per million years (Myr) and for the 16S rRNA is 0.46% per Myr. These results suggest that the evolutionary history of P. taurica in Greece is more complex than a single evolutionary invasion. The data analysed, stress the need for a reconsideration of the evolutionary history of Greek Podarcis species and help overcome difficulties that classical taxonomy has encountered at both the species level.

Complex estimates of evolutionary relationships in Tarentola mauritanica (Reptilia: Gekkonidae) derived from mitochondrial DNA sequences

Mitochondrial DNA (12S rRNA, 16S rRNA) sequences were analysed within Tarentola mauritanica and other selected species of Tarentola. Several highly genetically distinct lineages occur in North Africa, revealing phylogroups in southern and central Morocco, northern Morocco, Algeria, Tunisia, and Libya. A single haplotype characterizes populations across Spain, Portugal, Italy, Menorca, Crete, and Tunisia raising the possibility of an anthropogenic introduction followed by rapid population expansion throughout southern Europe. T. mauritanica is paraphyletic with respect to T. angustimentalis, a Canary islands endemic. The high genetic diversity observed across North Africa suggests T. mauritanica may represent a species complex.

Slow worm, Anguis fragilis (Reptilia: Anguidae) as a species complex: Genetic structure reveals deep divergences

Phylogenetic relationships of the Western Palearctic legless lizard genus Anguis were inferred based on a fragment of mitochondrial DNA and two nuclear protein-coding loci, C-mos and PRLR. A. cephallonica from the Peloponnese was confirmed as a valid species. It is the sister taxon to a clade comprising all other evolutionary lineages, which were shown to represent three distinct species: (1) A. fragilis sensu stricto occurring in Western and Central Europe, the north-western Balkans, with possibly isolated populations in the eastern Balkans, and presumably also in western Scandinavia and Italy; (2) A. colchica distributed from the eastern Czech Republic and the Baltic region eastward to northern Iran, presumably also in eastern Scandinavia, and the north-eastern Balkans; (3) A. graeca restricted to the southern Balkans, and partially sympatric with A. cephallonica. According to the more variable mitochondrial marker, A. graeca appears to be the sister species to A. colchica, and these taxa together form a sister clade to A. fragilis, whereas the less variable nuclear markers show A. colchica to be closer to A. fragilis. The C-mos gene has not provided substantial variation within this species complex, while the PRLR gene, which was used for the first time in phylogeographic study in a reptile, distinguished all species successfully. Intra-specific differentiation of A. colchica is discussed, and subspecific status of the Caucasian and Caspian populations is proposed. The uncovered genetic differences should be taken into account in all future biogeographical, morphological and ecological studies, as well as in conservation.

Cryptic diversity among Western Palearctic tree frogs: Postglacial range expansion, range limits, and secondary contacts of three European tree frog lineages (Hyla arborea group)

We characterize divergence times, intraspecific diversity and distributions for recently recognized lineages within the Hyla arborea species group, based on mitochondrial and nuclear sequences from 160 localities spanning its whole distribution. Lineages of H. arborea, H. orientalis, H. molleri have at least Pliocene age, supporting species level divergence. The genetically uniform Iberian H. molleri, although largely isolated by the Pyrenees, is parapatric to H. arborea, with evidence for successful hybridization in a small Aquitanian corridor (southwestern France), where the distribution also overlaps with H. meridionalis. The genetically uniform H. arborea, spread from Crete to Brittany, exhibits molecular signatures of a postglacial range expansion. It meets different mtDNA clades of H. orientalis in NE-Greece, along the Carpathians, and in Poland along the Vistula River (there including hybridization). The East-European H. orientalis is strongly structured genetically. Five geographic mitochondrial clades are recognized, with a molecular signature of postglacial range expansions for the clade that reached the most northern latitudes. Hybridization with H. savignyi is suggested in southwestern Turkey. Thus, cryptic diversity in these Pliocene Hyla lineages covers three extremes: a genetically poor, quasi-Iberian endemic (H. molleri), a more uniform species distributed from the Balkans to Western Europe (H. arborea), and a well-structured Asia Minor-Eastern European species (H. orientalis).

Conquering the Sahara and Arabian deserts: systematics and biogeography of Stenodactylus geckos (Reptilia: Gekkonidae)

BackgroundThe evolutionary history of the biota of North Africa and Arabia is inextricably tied to the complex geological and climatic evolution that gave rise to the prevalent deserts of these areas. Reptiles constitute an exemplary group in the study of the arid environments with numerous well-adapted members, while recent studies using reptiles as models have unveiled interesting biogeographical and diversification patterns. In this study, we include 207 specimens belonging to all 12 recognized species of the genus Stenodactylus. Molecular phylogenies inferred using two mitochondrial (12S rRNA and 16S rRNA) and two nuclear (c-mos and RAG-2) markers are employed to obtain a robust time-calibrated phylogeny, as the base to investigate the inter- and intraspecific relationships and to elucidate the biogeographical history of Stenodactylus, a genus with a large distribution range including the arid and hyper-arid areas of North Africa and Arabia.ResultsThe phylogenetic analyses of molecular data reveal the existence of three major clades within the genus Stenodactylus, which is supported by previous studies based on morphology. Estimated divergence times between clades and sub-clades are shown to correlate with major geological events of the region, the most important of which is the opening of the Red Sea, while climatic instability in the Miocene is hypothesized to have triggered diversification. High genetic variability is observed in some species, suggesting the existence of some undescribed species. The S. petrii - S. stenurus species complex is in need of a thorough taxonomic revision. New data is presented on the distribution of the sister species S. sthenodactylus and S. mauritanicus.ConclusionsThe phylogenetic hypothesis for the genus Stenodactylus presented in this work permits the reconstruction of the biogeographical history of these common desert dwellers and confirms the importance of the opening of the Red Sea and the climatic oscillations of the Miocene as major factors in the diversification of the biota of North Africa and Arabia. Moreover, this study traces the evolution of this widely distributed and highly specialized group, investigates the patterns of its high intraspecific diversity and elucidates its systematics.

Tail Shedding in Island Lizards [Lacertidae, Reptilia]: Decline of Antipredator Defenses in Relaxed Predation Environments

The ability of an animal to shed its tail is a widespread antipredator strategy among lizards. The degree of expression of this defense is expected to be shaped by prevailing environmental conditions including local predation pressure. We test these hypotheses by comparing several aspects of caudal autotomy in 15 Mediterranean lizard taxa existing across a swath of mainland and island localities that differ in the number and identity of predator species present. Autotomic ease varied substantially among the study populations, in a pattern that is best explained by the presence of vipers. Neither insularity nor the presence of other types of predators explain the observed autotomy rates. Final concentration of accumulated tail muscle lactate and duration of movement of a shed tail, two traits that were previously thought to relate to predation pressure, are in general not shaped by either predator diversity or insularity. Under conditions of relaxed predation selection, an uncoupling of different aspects of caudal autotomy exists, with some elements (ease of autotomy) declining faster than others (duration of movement, lactate concentration). We compared rates of shed tails in the field against rates of laboratory autotomies conducted under standardized conditions and found very high correlation values (r > 0.96). This suggests that field autotomy rates, rather than being a metric of predatory attacks, merely reflect the innate predisposition of a taxon to shed its tail.

Molecular phylogenetics and historical biogeography of the west-palearctic common toads (Bufo bufo species complex).

In most pan-Eurasiatic species complexes, two phenomena have been traditionally considered key processes of their cladogenesis and biogeography. First, it is hypothesized that the origin and development of the Central Asian Deserts generated a biogeographic barrier that fragmented past continuous distributions in Eastern and Western domains. Second, Pleistocene glaciations have been proposed as the main process driving the regional diversification within each of these domains. The European common toad and its closest relatives provide an interesting opportunity to examine the relative contributions of these paleogeographic and paleoclimatic events to the phylogeny and biogeography of a widespread Eurasiatic group. We investigate this issue by applying a multiproxy approach combining information from molecular phylogenies, a multiple correspondence analysis of allozyme data and species distribution models. Our study includes 304 specimens from 164 populations, covering most of the distributional range of the Bufo bufo species complex in the Western Palearctic. The phylogenies (ML and Bayesian analyses) were based on a total of 1988 bp of mitochondrial DNA encompassing three genes (tRNAval, 16S and ND1). A dataset with 173 species of the family Bufonidae was assembled to estimate the separation of the two pan-Eurasiatic species complexes of Bufo and to date the main biogeographic events within the Bufo bufo species complex. The allozyme study included sixteen protein systems, corresponding to 21 presumptive loci. Finally, the distribution models were based on maximum entropy. Our distribution models show that Eastern and Western species complexes are greatly isolated by the Central Asian Deserts, and our dating estimates place this divergence during the Middle Miocene, a moment in which different sources of evidence document a major upturn of the aridification rate of Central Asia. This climate-driven process likely separated the Eastern and Western species. At the level of the Western Palearctic, our dating estimates place most of the deepest phylogenetic structure before the Pleistocene, indicating that Pleistocene glaciations did not have a major role in splitting the major lineages. At a shallow level, the glacial dynamics contributed unevenly to the genetic structuring of populations, with a strong influence in the European-Caucasian populations, and a more relaxed effect in the Iberian populations.

Neogene climatic oscillations shape the biogeography and evolutionary history of the Eurasian blindsnake.

Typhlops vermicularis is the only extant scolecophidian representative occurring in Europe. Its main distribution area, the eastern Mediterranean, has a complicated geological and climatic history that has left an imprint on the phylogenies and biogeography of many taxa, especially amphibians and reptiles. Since reptiles are sensitive indicators of palaeogeographical and palaeoclimatic events, we investigated the intraspecific genealogy of T. vermicularis in a phylogeographical framework. A total of 130 specimens were analyzed, while the use of formalin and ethanol as preservatives called for a special treatment of the samples. Partial sequences of two mitochondrial (12S and ND2) and one nuclear (PRLR) marker were targeted and the results of the phylogenetic analyses (NJ, ML and BI) and the parsimony-network revealed the existence of 10 evolutionary significant units within this species. In combination with the results of the dispersal-vicariance analysis, we may conclude that the Eurasian blindsnake has encountered a sequence of extinction events, followed by secondary expansion from refugia. Estimation of divergence times showed that severe climatic changes between significantly wetter and drier conditions in the Late Neogene have played a key role on the evolutionary and biogeographical history of T. vermicularis. Additionally, both markers (mtDNA and nDNA) distinguished a largely-differentiated evolutionary lineage (Jordan and south Syria), which could even be reckoned as a full species. Our study reveals the existence of cryptic evolutionary lineages within T. vermicularis, which calls for further attention both on the protection of intraspecific varieties and the respective geographic areas that hold them.

Phylogeography of the ocellated skink Chalcides ocellatus (Squamata, Scincidae), with the use of mtDNA sequences: a hitch-hiker's guide to the Mediterranean.

We analyze geographic genetic variation in C. ocellatus to evaluate the influences of major climatic, paleogeographic and anthropogenic factors in its biogeographic history. Ninety four specimens from 61 populations were collected across all of its geographical range and analyzed based on partial mitochondrial sequences (cyt b, 12S, and ND1). Our results demonstrate that an ancestral form of C. ocellatus, which expanded in northwestern Africa at the end of Miocene, diverged in at least three separate evolutionary lineages approximately 4.57Ma: C. humilis spread south of the Sahara, while the other two (C. ocellatus sensu stricto) were restricted in the coastal North African region. The complicated history of the ocellated skink is a result of multiple vicariant phenomena followed by multiple active or passive dispersals. The Messinian salinity crisis and the re-flooding of the Mediterranean basin, the climatic transition from Middle to Upper Pliocene, and the hyperarid phase of the Sahara, affected the distribution and diversification of C. ocellatus, while in historical times it was introduced in the central Mediterranean islands and eastern Mediterranean region from Tunisia and Cyrenaica, respectively.