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Background Lizards of the genus Podarcis are widespread in the Mediterranean region, including islands and island archipelagos. These small-bodied lizards have a predominantly protective green-brown colouration. However, some populations display unusual patterns, in which the colouration is predominantly blue or uniformly black. This study explores the factors that influence this chromatic variation, whether environmental (climate and island conditions) or evolutionary (phylogenetic trait conservatism). The colouration of 1400 individuals (27 species) was analysed in the CIELAB colour space. Results Pagel’s λ indicated that colouration is weakly conserved within phylogenetic lineages. Although the island surface plays a key role in the chromatic variability of these lacertids, geographic isolation and climate hold less influence. The colouration of some small island populations tends to be uniform and dark, possibly due to intense intraspecific competition and lower predatory pressure. Conclusions This study highlights the importance of island populations in understanding the processes that favour the emergence of extreme phenotypes in small ectothermic vertebrates.

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The assessment of biodiversity by means that ignore the evolutionary relationships of the living forms can be quite misleading, resulting in the over-evaluation of some morphs and the ignorance of other evolutionary significant units. Molecular phylogeny, which is a potentially powerful tool for the conservation of biodiversity, provides essential evidence for setting conservation priorities on several taxa. Phylogenetic analyses can identify cryptic, genetically distinct lineages as well as non-distinctive lineages earlier perceived as separate taxa. The herpetofauna of the east Mediterranean region, which could be considered as one of nature’s most intensively active evolutionary laboratories, serves as an excellent example. Phylogenetic analyses on several lacertid taxa of this area have revealed cases of hidden diversity, paraphyly, new species and new endemics. In several cases the presence of cryptic species (Podarcis levendis, P. cretensis), species with very restricted distributions (P. gaigeae, P. milensis), paraphyletic (M. guttulta) or even polyphyletic species (O. elegans) were revealed. Such cases impose a considerable revision of the taxonomic views and conservation priorities. Based on these findings, many questions have been answered and certainly new ones have emerged, contributing not only to our knowledge on the east Mediterranean herpetofauna, but to broader issues of conservation biology, prioritizing conservation efforts and enhancing the need for a new multidisciplinary and innovative tool for screening and re-evaluating biodiversity.

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Recently, several works have focused on the lacertid lizards of the genus Podarcis, revealing cases of hidden diversity and paraphyly, and offering evidence that suggests the revision of the extant taxonomical arrangements within the genus. Hidden diversity and paraphyly have been shown to exist in the relationships betweentheBalkan species P. peloponnesiacaandP. erhardii as well. Herewecouple a molecular (mtDNA) dataset with a corresponding morphological one, consisting of morphometric and pholidotic characters, to check for concordance between the two. Phylogenetic analyses reinforced previous suggestions for paraphyly of P. erhardii with respect to P. peloponnesiaca.We found the variation of certain pholidotic characters concordant with the relationships inferred from partial mtDNA sequences, whereas morphometric characters were not. The latter is possibly due to greater influence of morphometric characters by environmental factors. To avoid the observed paraphyly we proceed with the description of the populations from Crete and the islet of Pori, until now designated as P. erhardii, as separate taxa at the species level.

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The ecological importance of islet endemics are in the front line of conservation efforts and thus the good knowledge of their biology is required. Podarcis levendis is a lacertid lizard, endemic to two rocky islets in the Cretan Sea, Greece, that was raised to specific level in 2008 and since then no data on its biology are available. Here we present the first ecological information on the species, focusing on population density, tail autotomy and feeding preferences. We recorded regenerated and damaged tails in the field and estimated population density with the transect method. We also dissected museum specimens and analyzed their stomach content. Regenerated tails were common and reached a considerable 71%. The latter finding could be attributed to the intense intraspecific competition due to high population density but also to the seasonal predation pressure by migratory birds. The diet of P. levendis coincides with that of other insular congenerics, including high percentages of plant material.

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Since the description of Podarcis levendis in 2008 only a few people have visited this species in ist habitat on the island of Pori and Lagouvardos. The authors have participated in a field trip to Pori where Podarcis levendis occours in high population density.

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Environmental temperatures considerably affect the reptilian ability for thermoregulation and harsh climatic conditions may impose a highly effective body temperature regulation to lizards. Such de- manding conditions are more common to extreme mainland habitats (e.g. deserts or mountains). To the contrary, islands have more benign climate conditions thanks to the thermal buffering effect of the surrounding sea. However, this favorable effect may be eliminated in small size islets where the scarcity of thermal shelters and exposure to high winds create challenging conditions. Here we investigate the impact of a tough islet habitat on the thermoregulation of Podarcis levendis, a lacertid lizard endemic to two rocky islets in the north Cretan Sea, Greece. To evaluate the thermoregulatory effectiveness of P. levendis we measured operative and body temperatures in the field and the preferred body temperatures in the lab. Analyses of the thermal data revealed an accurate, precise, and effective thermoregulator, achieving very high thermoregulation values (E 1⁄4 0.91, de db 1⁄4 7.6). This high effectiveness comes to compensate living in an inhospitable habitat as the operative temperatures denote (de 1⁄47.79). Our findings, together with the limited published literature, suggested the lack of a general pattern for all insular lizards and indicated a possible deviation for islet habitats.

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Many animals display complex colour patterns that comprise several adjacent, often contrasting colour patches. Combining patches of complementary colours increases the overall conspicuousness of the complex pattern, enhancing signal detection. Therefore, selection for conspicuousness may act not only on the design of single colour patches, but also on their combination. Contrasting long- and short-wavelength colour patches are located on the ventral and lateral surfaces of many lacertid lizards. As the combination of long- and short-wavelength-based colours generates local chromatic contrast, we hypothesized that selection may favour the co-occurrence of lateral and ventral contrasting patches, resulting in complex colour patterns that maximize the overall conspicuousness of the signal. To test this hypothesis we performed a comparative phylogenetic study using a categorical colour classification based on spectral data and descriptive information on lacertid coloration collected from the literature. Our results demonstrate that conspicuous ventral (long wavelength-based) and lateral (short wavelength-based) colour patches co-occur throughout the lacertid phylogeny more often than expected by chance, especially in the subfamily Lacertini. These results suggest that selection promotes the evolution of the complex pattern rather than the acquisition of a single conspicuous colour patch, possibly due to the increased conspicuousness caused by the combination of colours with contrasting spectral properties.

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The complex geological history of the Balkan Peninsula and especially of the Hellenic area (multiple geological events of land connections) during the late Tertiary have likely contributed to the diversification and distribution of many terrestrial animals. Located at the margin of the Eurasian and African plates, this area has experienced tremendous geological alterations since the late Tertiary. Connections offered the opportunities for biological dispersal, while submergence of land bridges brought about distributive isolation among related taxa. If this was a major element influencing the formation of the rich fauna of the Hellenic area, then the phylogenetic relationships of terrestrial taxa should reflect these paleogeographic events. Compared with what is known for the geological history of this region, the impact of those geological events on the historical biogeography of terrestrial animals is less well understood. The reconstruction of phylogenies is of primary importance in the understating of the dynamic patterns of evolution, i.e. the biogeography of a group and the bases of its biological diversity at any level. Although the phylogeny of the genus Podarcis has been the subject of much discussion the relationships among the species are still unclear. Because morphology is so uniform, it provides few characters for phylogenetic analysis, and these tend to be conflicting. Various karyological, immunological and protein electrophoretic studies have been made, but these usually involve only a minority of species, and results from different species combinations are equivocal. Wall lizards of the genus Podarcis (Sauria, Lacertidae) comprises 17-18 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 geographic coherence (Western Island group, South western group, Italian group and Balkan group). The Balkan species are divided in two subgroups: the subgroup of P. taurica (P. taurica, P. milensis, P. gaigeae and perhaps P. melisellensis), and the subgroup of P. erhardii (P. erhardii and P. peloponnesiaca). We addressed the question of phylogenetic relations among the species of Podarcis encountered in Balkan Peninsula, as they can be inferred from partial mtDNA (cyt b and 16S) and nuclear (c-mos) sequences. Our data support the monophyly of Podarcis and suggest that there are three phylogenetic clades: the clade of P. taurica (P. taurica, P. gaigeae, P. milensis, and P. melisellensis); the clade of P. erhardii (P. erhardii and P. peloponnesiaca) and the clade of P. muralis (P. muralis and P. sicula). The phylogenetic affiliations produced from the molecular data do not agree with the species and especially subspecies groupings predicted from the morphological classification of the populations sampled. By examining intraspecific variability we have found that extant populations of P. erhardii are paraphyletic. The high level of genetic differentiation observed in the mtDNA data between the P. erhardii populations from the Crete and Pori islands and the rest of P. erhardii samples from Cyclades and continental Greece and its phylogenetic position raises questions regarding the inclusion of those populations (Crete and Pori) within P. erhardii. Since, based on morphology, P. peloponnesiaca is a well defined species found in sympatry with P. e. livadhiaca and accepted today as such, then Podarcis from Crete and Pori would also need to be raised to specific rank to avoid the paraphyly of P. erhardii. However, although the differentiation of populations from Crete and Pori islands is clear, we suggest the use of PhyloCode in order to avoid taxonomic confusion at least until further research mainly on morphology becomes available. Thus, for the time being, we refer to wall lizards of Crete and Pori P. erhardii*. With regard to morphological subspecies of P. taurica, P. gaigeae and P. erhardii, it is clear that they do not represent monophyletic units and should be re-evaluated in the light of new evidence. The topology of the phylogenetic trees produced and the genetic distances among the clades of the Podarcis may describe a biogeographic hypothesis for these species in the Balkan area. The pattern of the distribution of the proposed taxa is congruent with existing paleogeographic evidence, as inferred by the application of a molecular clock, which supports the view that DNA sequences may be a useful tool for the study of paleogeography. The data analyzed, stress the need for a reconsideration of the evolutionary history of Balkan Podarcis species and help overcome difficulties that classical taxonomy has encountered at both the species and subspecies level. As a whole, the examination of mtDNA lineages in the lizards of genus Podarcis may contribute substantially to the refining of its taxonomic status. Phylogenetic information can now be added to the knowledge of their morphology and distribution, producing a more accurate taxonomy for this group. Our results also confirm that the molecular information in conjunction with geological data can be used to resolve questions about the paleogeography of a region or on the phylogeography of a species.

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Wall lizards of the genus Podarcis (Sauria, Lacertidae) are the predominant reptile group in southern Europe, including 24 recognized species. Mitochondrial DNA data have shown that, with the exception of P. muralis, the Podarcis species distributed in the Balkan peninsula form a species group that is further sub-divided into two subgroups: the one of “P. tauricus” consisting of P. tauricus, P. milensis, P. gaigeae, and P. melisellensis, and the other of “P. erhardii” comprising P. erhardii, P. levendis, P. cretensis, and P. peloponnesiacus. In an attempt to explore the Balkan Podarcis phylogenomic relationships, assess the levels of genetic structure and to re-evaluate the number of extant species, we employed phylogenomic and admixture approaches on ddRADseq (double digested Restriction site Associated DNA sequencing) genomic data. With this efficient Next Generation Sequencing approach, we were able to obtain a large number of genomic loci randomly distributed throughout the genome and use them to resolve the previously obscure phylogenetic relationships among the different Podarcis species distributed in the Balkans. The obtained phylogenomic relationships support the monophyly of both aforementioned subgroups and revealed several divergent lineages within each subgroup, stressing the need for taxonomic re-evaluation of Podarcis’ species in Balkans. The phylogenomic trees and the species delimitation analyses confirmed all recently recognized species (P. levendis, P. cretensis, and P. ionicus) and showed the presence of at least two more species, one in P. erhardii and the other in P. peloponnesiacus.

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The monophyletic species subgroup of Podarcis tauricus is distributed in the western and southern parts of the Balkans, and includes four species with unresolved and unstudied inter- and intra-specific phylogenetic relationships. Using sequence data from two mitochondrial and three nuclear genes and applying several phylogenetic methods and species delimitation approaches to an extensive dataset, we have reconstructed the phylogeny of the Podarcis wall lizards in the Balkans, and re-investigated the taxonomic status of the P. tauricus species subgroup. Multilocus analyses revealed that the aforementioned subgroup consists of five major clades, with P. melisellensis as its most basal taxon. Monophyly of P. tauricus sensu stricto is not supported, with one of the subspecies (P. t. ionicus) displaying great genetic diversity (hidden diversity or cryptic species). It comprises five, geographically distinct, subclades with genetic distances on the species level. Species delimitation approaches revealed nine species within the P. tauricus species subgroup (P. melisellensis, P. gaigeae, P. milensis, and six in the P. tauricus complex), underlining the necessity of taxonomic re-evaluation. We thus synonymize some previously recognized subspecies in this subgroup, elevate P. t. tauricus and P. g. gaigeae to the species level and suggest a distinct Albanian-Greek clade, provisionally named as the P. ionicus species complex. The latter clade comprises five unconfirmed candidate species that call for comprehensive studies in the future.

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In recent years, great attention has been paid to many Podarcis species for which the observed intra-specific variability often revealed species complexes still characterized by an unresolved relationship. When compared to other species, P. siculus underwent fewer revisions and the number of species hidden within this taxon may have been, therefore, underestimated. However, recent studies based on genetic and morphological data highlighted a marked differentiation of the populations inhabiting the western Pontine Archipelago. In the present work we used published genetic data (three mitochondrial and three nuclear gene fragments) from 25 Podarcis species to provide a multilocus phylogeny of the genus in order to understand the degree of differentiation of the western Pontine populations. In addition, we analyzed new morphometric traits (scale counts) of 151 specimens from the main islands of the Pontine Archipelago. The phylogenetic analysis revealed five principal Podarcis groups with biogeographic consistency. The genetic distinctiveness of the Podarcis populations of the western Pontine Islands is similar or even more ancient than those observed in numerous other pairs of Podarcis sister species. In the light of these evidences we raise the western Pontine lizards to specific rank; thus they should be referred to as Podarcis latastei.

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Research on the taxonomy of European amphibians and reptiles has increased noticeably over the last few decades, indicating the need for recognition of new species and the cancellation of others. This paper provides a critical review of recent changes and draws up a tentative species list.

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The last species list of the European herpetofauna was published by Speybroeck, Beukema and Crochet (2010). In the meantime, ongoing research led to numerous taxonomic changes, including the discovery of new species-level lineages as well as reclassifications at genus level, requiring significant changes to this list. As of 2019, a new Taxonomic Committee was established as an official entity within the European Herpetological Society, Societas Europaea Herpetologica (SEH). Twelve members from nine European countries reviewed, discussed and voted on recent taxonomic research on a case-by-case basis. Accepted changes led to critical compilation of a new species list, which is hereby presented and discussed. According to our list, 301 species (95 amphibians, 15 chelonians, including six species of sea turtles, and 191 squamates) occur within our expanded geographical definition of Europe. The list includes 14 non-native species (three amphibians, one chelonian, and ten squamates).

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In recent years, there have been numerous studies focusing on the systematics of the wall lizards of the genus Podarcis, uncovering several cases of cryptic diversity, such as the cases of the Cretan (southern Aegean) and Pori (islet between Crete and Peloponnisos) wall-lizards that were recently recognized as distinct species (P. cretensis and P. levendis, respectively). In this study, nucleotide sequences from five genes (two mitochondrial – 16S rRNA & cytb and three nuclear – MC1R, pod15b & pod55) were used to infer intra- and inter- phylogenetic relationships of P. cretensis, P. levendis, and P. peloponnesiacus through Bayesian Inference and Maximum Likelihood approaches using P. erhardii as outgroup. Moreover, the boundaries of the putative species were evaluated by employing several species delimitation methods, aiming to ‘determine’ the exact number of species and their phylogenetic status. The phylogenetic analyses revealed that all the examined species are monophyletic. Among them P. levendis, although without statistical support, appear to be more closely related to P. peloponnesiacus. The Cretan species is further subdivided into three major groups of lineages with distinct geographic distributions whereas P. peloponnesiacus into two. The above results combined with the analyses of species delimitation stress the need for a taxonomic reconsideration of the studied taxa both at the species and subspecies level.

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The evolutionary history of taxa with limited overseas dispersal abilities is considered to be majorly infl;uenced by vicariant events constituting them as model organisms for the interpretation of evolutionary processes. An excellent candidate are the wall lizards of the genus Podarcis exhibiting an impressive level of genetic and morphological diversification and harboring several cases of recently discovered cryptic diversity. In this study, we investigated the effect of palaeogeographic events on the wall lizards’ biodiversity patterns in the Aegean (Greece) as well as the evolutionary processes that acted both in space and time. To accomplish that we studied a group of three endemic Podarcis species (i.e., P. cretensis, P. levendis, and P. peloponnesiacus) both at the intra and interspecific levels employing mitochondrial and nuclear DNA sequence data as well as microsatellites. Furthermore, presence information coupled with bioclimatic data (i.e., species distribution modeling, and niche similarity analyses) shed light on the necessary ecological factors for the species’ occurrence. These approaches revealed yet another case of cryptic diversity for this group of lizards, with the existence of two slightly overlapping lineages within P. peloponnesiacus and highly structured populations within P. cretensis. Species diversification occurred during the Pliocene with P. peloponnesiacus divergence into the two lineages dating back to 1.86 Mya. Furthermore, temperature and precipitation related environmental parameters were the most important ones regarding the current distribution of the studied species. Based on the results, we propose a more detailed phylogeographic scenario where both the paleogeography of the area and several environmental parameters have shaped the genetic diversity and the current distribution pattern of this species group.