×

Die vorliegende Studie behandelt die Nahrungszusammensetzung dreier nichtsympatrischer Eidechsenarten von den Ägäischen Inseln, Griechenland. Der Mageninhalt von 157 Exemplaren von Podarcis milensis (62), Podarcis gaigeae (50) und Podarcis erhardii (45) wurde auf Beuterückstände untersucht. Alle Tiere kamen aus Museumssammlungen und waren im Sommer gefunden worden. In dieser Jahreszeit nehmen Podarcis milensis und Podarcis gaigeae ähnliche Nahrung auf, hauptsächlich Ameisen, Coleoptera und Insektenlarven, während Podarcis erhardii Coleoptera und Orthoptera erbeutet. Die Ergebnisse werden im Zusammenhang mit der verfügbaren Beute diskutiert.

×

In the herpetological collection of ZFMK 528 scientific species group names are represented by type materi- al. Of these, 304 names are documented by primary type specimens (onomatophores) while for 224 further names sec- ondary type specimens (typoids) are available, ranging chronologically from 1801 to 2010. The list is a shortened pred- ecessor of a comprehensive type catalogue in progress. It lists name bearing types with their catalogue numbers includ- ing information on further type series members also in other institutions, while secondary types are listed only by pres- ence, both in ZFMK and other collections including holotype repositories. Geographic origin and currently valid names are also provided.

×

In this paper, we demonstrate how to take advantage of the large number of spatial samples provided by commercial multispectral RGB imagers. We investigate the possibility to use various multidimensional histograms and probability distributions for decomposition and predictive models. We show how these methods can be used in an example using images of different Skyros wall lizards and demonstrate improved performance in prediction of color morph compared with traditional parameterization techniques of spatial variance.

×

The Greek lizard fauna consists of 26 species from which 5 are monotypic and the other ones are represented by a total of 86 subspecies. Five species and 61 subspecies are endemic of Greece. A checklist including the geographical distribution of each taxon in the Greek region is presented.

×

Island populations may evolve distinct behavioral repertoires as a response to the conditions of insular life. Strong intraspecific competition is typical in insular lizards and may include cannibalism. In this study, we investigated sexual and age patterns of aggression in two populations of the Skyros wall lizard (Podarcis gaigeae), one from the main island of Skyros (Aegean Sea, Greece) and another from the satellite islet Diavates. The latter is terrestrial predator-free biotope, hosting a dense population of large-bodied lizards that have been reported to exert cannibalism. In staged encounters, we examined the aggressive propensities of adult male and female lizards against their age-peers and juveniles. Males from both populations were much more aggressive than females toward juveniles and other adults. Males from Diavates were more frequently aggressive to juveniles and other male lizards than males from Skyros. Diavates cannibals also captured their targets at shorter latency. We ascribe this distinct behavioral pattern to the high population density. Infanticide and intra-male aggressiveness confer two great advantages to cannibals: food and elimination of future rival.

×

Island populations may evolve distinct behavioral repertoires as a response to the conditions of insular life. Strong intraspecific competition is typical in insular lizards and may include cannibalism. In this study, we investigated sexual and age patterns of aggression in two populations of the Skyros wall lizard (Podarcis gaigeae), one from the main island of Skyros (Aegean Sea, Greece) and another from the satellite islet Diavates. The latter is terrestrial predator-free biotope, hosting a dense population of large-bodied lizards that have been reported to exert cannibalism. In staged encounters, we examined the aggressive propensities of adult male and female lizards against their age-peers and juveniles. Males from both populations were much more aggressive than females toward juveniles and other adults. Males from Diavates were more frequently aggressive to juveniles and other male lizards than males from Skyros. Diavates cannibals also captured their targets at shorter latency. We ascribe this distinct behavioral pattern to the high population density. Infanticide and intra-male aggressiveness confer two great advantages to cannibals: food and elimination of future rival.

×

Lizards and Eleonora’s falcon occur on many Mediterranean islets. Data given in literature and new observations concerning their asymmetrical interactions, which have been reviewed and illustrated, allow to regard those as a commensal relationship typical on these micro-insular ecosystems. Some considerations on the ecological, ecomorphological and phenological traits involved on this commensalism are also briefly discussed.

×

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.

×

The Sporades are one of the most biologically important archipelagos in the Aegean Sea (Greece) and have received priority conservation over the last 50 years. However, despite numerous early efforts, its herpetofauna is only partially described, resulting in many distributional gaps that have prevented adequate understanding and management of the resident species communities. We review one century of bibliography from the Northern Sporades and combine this information with a review of museum specimens and insights from numerous extensive field surveys over the last near-decade to provide for the first time a comprehensive picture of the reptiles and amphibians of the archipelago. We report here on 26 new island records and find that the herptile communities of the region are largely derived from the herpetofauna of the nearby Thessaly mainland, with only a few introduced taxa. There is also a small but significant set of endemic taxa in the archipelago. Island species richness declines with decreasing island size and increasing duration of island isolation. Herptile communities on smaller islands are progressively nested subsets of the communities on larger islands. The presence of reptile species depends sensitively on the condition and management of native ecosystems. While non-aquatic species maintain largely healthy populations, most populations are under pressure from the combined effects of rampant tourist development, the destruction and degradation of rare wetland habitats, and the abandonment of traditional agricultural landscapes. We provide recommendations regarding sustainable management of the local reptile and amphibian populations.

×

In recent years there has been an exponential increase in the amount of published DNA sequences, as it has become one of the most popular sources of data for reconstructing phylogenies. A number of studies have attempted to resolve the relationships of groups of lacertids using mitochondrial DNA sequence data, in particular Podarcis and Gallotia (e.g. THORPE et al., 1994; 1996; GONZALEZ et al., 1996; FU et al., 1997; HARRIS, 1997; HARRIS et al., 1998a; 1999; CASTILLA et al., 1999a,b). Reassessment of these data suggest some alternative phylogenies to those previously published, and also highlight possible problems. Two studies have attempted to unravel the phylogeny of the whole family using mitochondrial DNA sequences (FU, 1998; HARRIS et al., 1998b). By combining these essentially congruent data sets, and reanalysing levels of support for the phylogenies produced, a more complete estimate of relationships across the family is produced. This is then compared to alternative sources of evidence, primarily morphological (ARNOLD, 1989), biochemical (MAYER & BENYR, 1994) and karyological (OLMO et al., 1993). Reasons for discrepencies are discussed, as are the relative advantages and disadvantages of the different sources of phylogenetic inference.

×

Aim: Animal body sizes are often remarkably variable across islands, but despite much research we still have a poor understanding of both the patterns and the drivers of body size evolution. Theory predicts that interspecific competition and predation pressures are relaxed on small, remote islands, and that these conditions promote body size evolution. We studied body size variation across multiple insular populations of 16 reptile species co-occurring in the same archipelago and tested which island characteristics primarily drive body size evolution, the nature of the common patterns, and whether co-occurring species respond in a similar manner to insular conditions. Location: Aegean Sea islands. Time period: 1984–2016. Major taxa studied: Reptiles. Methods: We combined fieldwork, museum measurements and a comprehensive literature survey to collect data on nearly 10,000 individuals, representing eight lizard and eight snake species across 273 islands. We also quantified a large array of predictors to assess directly the effects of island area, isolation (both spatial and temporal), predation and interspecific competition on body size evolution. We used linear models and meta-analyses to determine which predictors are informative for all reptiles, for lizards and snakes separately, and for each species. Results: Body size varies with different predictors across the species we studied, and patterns differ within families and between lizards and snakes. Each predictor influenced body size in at least one species, but no general trend was recovered. As a group, lizards are hardly affected by any of the predictors we tested, whereas snake size generally increases with area and with competitor and predator richness, and decreases with isolation. Main conclusions: No factor emerges as a predominant driver of Aegean reptile sizes. This contradicts theories of general body size evolutionary trajectories on islands. We conclude that overarching generalizations oversimplify patterns and processes of reptile body size evolution on islands. Instead, species’ autecology and island particularities interact to drive the course of size evolution.

×

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.

×

Small-lizards from the Greek islands Milos and Skiros are compared with populations from the continent of Podarcis taurica ionica, Podarcis muralis albanica and Podarcis erhardii by employing protein-electrophoretic data for 18 genloci. The gen frequencies of the polymorph loci are given and the genetic distances are calulated according to Nei. Extension of genetic distances is discussed. Podarcis milensis can be confirmed as a species. Populations of Milos and Skiros have shown to be closest related, both have to be considered as closely related to Podarcis taurica and not to Podarcis muralis.

×

Aim Body size is instrumental in influencing animal physiology, morphology, ecology and evolution, as well as extinction risk. I examine several hypotheses regarding the influence of body size on lizard evolution and extinction risk, assessing whether body size influences, or is influenced by, species richness, herbivory, island dwelling and extinction risk. Location World-wide. Methods I used literature data and measurements of museum and live specimens to estimate lizard body size distributions. Results I obtained body size data for 99% of the world`s lizard species. The body size–frequency distribution is highly modal and right skewed and similar distributions characterize most lizard families and lizard assemblages across biogeographical realms. There is a strong negative correlation between mean body size within families and species richness. Herbivorous lizards are larger than omnivorous and carnivorous ones, and aquatic lizards are larger than non-aquatic species. Diurnal activity is associated with small body size. Insular lizards tend towards both extremes of the size spectrum. Extinction risk increases with body size of species for which risk has been assessed. Main conclusions Small size seems to promote fast diversification of disparate body plans. The absence of mammalian predators allows insular lizards to attain larger body sizes by means of release from predation and allows them to evolve into the top predator niche. Island living also promotes a high frequency of herbivory, which is also associated with large size. Aquatic and nocturnal lizards probably evolve large size because of thermal constraints. The association between large size and high extinction risk, however, probably reflects a bias in the species in which risk has been studied.

×

Aim Temperature influences most components of animal ecology and life history – but what kind of temperature? Physiologists usually examine the influence of body temperatures, while biogeographers and macroecologists tend to focus on environmental temperatures. We aim to examine the relationship between these two measures, to determine the factors that affect lizard body temperatures and to test the effect of both temperature measures on lizard life history. Location World-wide. Methods We used a large (861 species) global dataset of lizard body temperatures, and the mean annual temperatures across their geographic ranges to examine the relationships between body and mean annual temperatures.We then examined factors influencing body temperatures, and tested for the influence of both on ecological and life-history traits while accounting for the influence of shared ancestry. Results Body temperatures and mean annual temperatures are uncorrelated. However, accounting for activity time (nocturnal species have low body temperatures), use of space (fossorial and semi-aquatic species are ‘colder’), insularity (mainland species are ‘hotter’) and phylogeny, the two temperatures are positively correlated. High body temperatures are only associated with larger hatchlings and increased rates of biomass production. Annual temperatures are positively correlated with clutch frequency and annual longevity, and negatively correlated with clutch size, age at first reproduction and longevity. Main conclusions Lizards with low body temperatures do not seem to have ‘slower’ life-history attributes than species with high body temperatures. The longer seasons prevalent in warm regions, and physiological processes that operate while lizards are inactive (but warm enough), make environmental temperatures better predictors of lizard life-history variation than body temperatures. This surprisingly greater effect of environmental temperatures on lizard life histories hints that global warming may have a profound influence on lizard ecology and evolution.

×

Islands are usually species-poor and insular animal communities likewise usually harbour fewer species than equivalent mainland communities. Intraspecific competition on islands is therefore usually weaker than it is on the mainland. Predation pressure often also decreases on islands, and some in many instances some insular organisms face no predators at all. Faced with such relaxed predation and competition pressures insular animals can evolve to exploit the wider resource spectrum than they can access in more species-rich environments. An extension of this scenario, called the “niche variation hypothesis”, results in populations of depauperate communities evolving greater morphological variability. This variability is often thought to manifest itself in enhanced sexual size dimorphism, with the larger sex growing larger still, whereas individuals of the smaller sex grow smaller, so as to reduce intra-specific competition. A clear prediction of this theory is therefore that communities with more competitors or predators will be less dimorphic. We tested this by measuring the sexual size dimorphism (SSD) of two Podarcis species in two Aegean archipelagos. We measured SVLs of female and male lizards across many islands and examined it against the number of other lacertid lizards, the number all lizards, and the numbers of snake species on each island. For each species (Podarcis gaigeae, 16 islands; P. erhardii, 27 islands) we also examined whether the presence, rather than the number of lacertids, lizards, and snakes, affects the degree of SSD. Podarcis gaigeae was, on average, more dimorphic than P. erhardii (males 14% longer vs. 6%). In neither species, however, was the degree of SSD affected by either the number or the presence of snakes, lacertid lizards or lizards in general. We conclude that on small islands lacking other reptiles the resource base is likely more limited as well, and thus does not allow the sexes to diverge to specialize on different-sized prey.

×

The authros report on their observations on Podarcis gaigeae (Skyros Wall Lizard) on the Skyros archipelago. In Addition to the island of Skyros, two offshore islets with populations of particularly large lizards have been visited.

×

Skyros island is well known for the famous pony, a typical case of dwarfism. At the same Archipelago though, there is an impressive case of gigantism, the endemic lizard of Skyros (Podarcis gaigeae), present only in the islet Mesa Diavates. This population is characterised by high density and cannibalism while a numerous seagull colony nests in the islet. According to the “island rule”, all these features favour gigantism. This study tried to clarify the underlying factors of gigantism and its implications to the overall biology of lizards. It failed to detect another incident of gigantism after sampling all islets of the Archipelago. This finding certifies the uniqueness of the Diavates population, though all insular lizards had larger body size than their Skyros conspecifics while an intermediate case was found at Lakonissi. High food availability is the main factor diversifying Diavates from the rest of the islets, supported by breeding seagulls that provide nutrients. Thanks to seabird contribution to the energy flow and the particular substrate of the islet, vegetation is lush and has switched to more nitrophilous species, fueling an augmented primary productivity. Minimal predation pressure has increased lizard population densities, which experience stronger intraspecific competition, expressed even as cannibalism. Under these circumstances large body size turns to be an advantage for both juveniles (since they may survive from cannibalism) and male adults (that have access to an extra food resource through cannibalism but also possess higher social status, territoriality and reproductive success). The impact of gigantism on reproductive output was strong. Contrary to classical life-history strategies that predict for clutches of either many but smaller eggs or few but larger eggs, in this case females from Diavates lay many and larger eggs. No effect was found regarding thermoregulation. The occurrence of gigantism and unusual reproductive investment in these small island populations is probably best explained by the occurrence of two underlying factors: (i.) the existence of striking cannibalistic behaviours in the form of attacks to the tail and intense intraspecific predation on juveniles, and (ii.) substantial marine subsidies by resident seabird colonies

×

Grazing of goats on Mediterranean islets is a common practice. Its consequences on plant communities are well documented, although not on vertebrates. We aim to shed light on the effect of livestock farming on lizards by investigating five populations of the insular lizard, Podarcis gaigeae, differing in the duration and intensity of grazing. Data on grazing regime, invertebrate abundance, tick prevalence, infestation levels, gull nests and lizard densities were collected during a period of 6 consecutive years. Grazing had a negative impact on insect populations, thus decreasing food availability for lizards. Tick prevalence and infestation levels were higher in places of continuous grazing. Goat activity disturbed gulls, which avoid nesting, so depriving the islets of marine subsidies. As a consequence of all these factors, lizard densities were higher in ungrazed and lower in grazed biotopes. Grazing effects were more severe on islets communities than on the main island populations. Our data imply that management action should be taken to conserve the highly diverse islet populations.

×

Temperature sensitivity of digestive processes has important ramifications for digestive performance in ectothermic vertebrates. We conducted a comparative analysis of temperature effects on digestive processes [gut passage times (GPTs) and apparent digestive efficiencies (ADEs)] in five lacertid lizards occurring in insular (Podarcis erhardii, P. gaigeae), and mainland (P. muralis, P. peloponnesiaca, Lacerta graeca) Mediterranean environments. GPTs were negatively correlated to temperature with mainland taxa having 10–20% longer GPTs than island taxa. In contrast to previous studies that estimate ADEs using bomb calorimetry, we compare ADEs by analyzing discrete efficiencies for lipids, sugars and proteins at three temperature regimes (20, 25, and 30°C); each of these categories produces different results. ADEs for lipids and sugars showed a monotonic increase with temperature whereas ADEs for proteins decreased with temperature. Island taxa had consistently higher ADEs than their mainland counterparts for lipids and for proteins but not for sugars. They are characterized by superior energy acquisition abilities despite significantly shorter GPTs. Their increased digestive performance relative to the mainland species appears to allow them to maximize energy acquisition in unproductive island environments where food availability is spatially and seasonally clustered.

×

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.

×

Differences in ecological conditions can result in the evolution of dramatic inter-population shifts in whole suites of traits. We studied variation in reproductive output in three lizard populations of the Skyros Wall Lizard (Podarcis gaigeae, Lacertidae) endemic to the Skyros Archipelago (Greece), which live under similar climatic conditions but differ in predation pressure and food availability. Based on the “island syndrome” hypothesis, we predicted that females from island populations would produce larger, but fewer offspring. The study populations differ conspicuously in average body size, with males from the satellite Lakonissi and Diavates islets being respectively 20% and 39% larger than males from the main Skyros Island. Lizards from these predator-free islets produced eggs of larger size than the main Skyros population; however, they also produced significantly larger clutches than the Skyros population (2.31±0.83 and 2.73±1.0 vs. 1.97±0.58 eggs). All inter-population differences in clutch size, clutch volume, and egg size were explained by corresponding differences in average body size of the dams, revealing that across all populations, reproductive effort scaled similarly with maternal body size. There was no evidence of trade-offs between egg size and clutch size as generally encountered in many reptile taxa. The occurrence of this unusual pattern of reproductive investment among islet populations of giants is probably best explained by the occurrence of two underlying drivers: first, the substantial marine subsidies by resident seabird colonies and second, the existence of intense cannibalistic behaviors in the form of attacks to the tail and severe intraspecific predation on juveniles. This suggests that subsidies-driven gigantism in island endemics may free species from such trade-offs and allow a population to maximize reproductive output in multiple, normally conflicting dimensions.

×

Resource availability, competition, and predation commonly drive body size evolution. We assess the impact of high food availability and the consequent increased intraspecific competition, as expressed by tail injuries and cannibalism, on body size in Skyros wall lizards (Podarcis gaigeae). Lizard populations on islets surrounding Skyros (Aegean Sea) all have fewer predators and competitors than on Skyros but differ in the numbers of nesting seabirds. We predicted the following: (1) the presence of breeding seabirds (providing nutrients) will increase lizard population densities; (2) dense lizard populations will experience stronger intraspecific competition; and (3) such aggression, will be associated with larger average body size. We found a positive correlation between seabird and lizard densities. Cannibalism and tail injuries were considerably higher in dense populations. Increases in cannibalism and tail loss were associated with large body sizes. Adult cannibalism on juveniles may select for rapid growth, fuelled by high food abundance, setting thus the stage for the evolution of gigantism.

×

Effective digestion is decisive for survival. In nature, where most animals feed sporadically, high digestive performance guarantees they will gain the most out of their infrequent meals. Larger body size implies higher energy requirements and digestion should function properly to provide this extra energy. Comparing Skyros wall lizards (Podarcis gaigeae) from Skyros Island to large (“giant”) lizards from a nearby islet, we tested the hypothesis that digestion in large individuals is more efficient than in small individuals. We anticipated that giant lizards would have higher gut passage time (GPT), longer gastrointestinal (GI) tracts and higher apparent digestive efficiencies (ADE) for lipids, sugars and proteins. These predictions were only partially verified. Giant lizards indeed had longer (than expected based on body length) GI tract and longer GPTs but achieved higher ADE only for proteins, while ADEs for lipids and sugars did not differ from the normal-sized lizards. We postulated that the observed deviations from the typical digestive pattern are explained by cannibalism being more prominent on the islet. Giant lizards regularly consume tail fragments of their conspecifics and even entire juveniles. To break down their hard-to-digest vertebrate prey, they need to extend GPT and thus they have developed a longer GI tract. Also, to fuel tail regeneration they have to raise ADEproteins. It seems that larger size, through the evolution of longer GI tract, enables giant lizards to take advantage of tails lost in agonistic encounters as a valuable food source.

×

Caudal autotomy is one of the most effective and widespread defensive mechanisms among lizards. When predators grasp the tail, lizards are able to shed it from the point of the attack and further. Numerous factors have been reported to affect tail-shedding performance such as temperature, age, predation pressure, intraspecific competition etc. Interestingly, the impact of sex on tail loss remains greatly understudied. Here, we analyzed tail autotomy performance, simulated in the lab, in 12 species of lacertid lizards belonging to five genera (Algyroides, Anatololacerta, Hellenolacerta, Ophisops, Podarcis). Our aim was to investigate whether sex affects caudal autotomy and/or the duration of post-autotomic tail movement. We failed to detect any effect of sex on tail loss in the species examined. Also, we did not find any sexual impact on the duration of tail movement after autotomy, with a single exception. Our findings suggest that autotomy serves as a defensive tactic equally in both sexes and is used in the same extent.

×

Gigantism is a well known phenomenon in various taxa and has been described from many insular populations. Intraspecific competition emerges as one of the most acceptable among the various explanations that has been proposed. Though intra-species competition is considered rather uncommon among lacertids, there is strong evidence from dense insular populations supporting the opposite theory. In this paper we report another case of gigantism in a system comprised excusively of islands. Skyros wall lizard (Podarcis gaigeae) is endemic to Skyros Archipelago (western Aegean Sea). In 2 cases gigantic populations were discovered in the tiny islets Diavates and Lakonissi, close to the west coast of the main island. Both islets host dense populations (800 and 500 ind /ha respectively). In this study we assess the reproductive characteristcs of these two populations and we compare them to a population from Skyros. Tail autotomy is related traditionaly to predation regime. However predation pressure in our study system varied from relaxed (Skyros) to minimum (Diavates and Lakonissi). Hence we believe that the high proportions of regenerated tails observed in the islet populations (45-65% in comparison to 30% in the case of Skyros) could be interpreted as sign of a strong intraspecific competition. This approach is further reinforced by the high canibalism in Diavates. In our study we combined field and laboratory observations with measurements from museum speciments. In all cases females produced two or three clutches and oviposition lasted from early March until middle summer. Clutch size was bigger in the case of the gigantic populations of Diavates (2.69 eggs) and Lakonissi (2.17) in comparison to Skyros population (1.94). Egg volume, and subsequently clutch volume, followed that grade according to which the bigger eggs were born in Diavates and the smaller in Skyros. SVL of juveniles replicated once more that same pattern: females from Diavates gave birth to young giants (33 cm) while hatchlings` size in Lakonissi was smaller (30.2 cm) but still higher than in Skyros (27.8 cm). Statistical analysis revealed that clutch size corrected for maternal SVL is correlated to egg volume only in the case of Diavates giants. According to our results bigger lizards produce more and larger hatchlings. Under this light gigantism could be a solution to eliminate the body morphology constrains on the reproductive output in lizards, offering the opportunity to increase both clutch size and egg volume and consequently offspring size. It is well established that large juveniles are better survivors, a pivotal advantage when grow up under difficult conditions, as in the case of the islets under study.

×

The practice of free-range goat grazing in islets is common throughout Mediterranean Sea with well-documented consequences on plant communities. In the case of lizards grazing has been reported to alter vegetation providing less cover from avian predators, increasing thus predation risk. In this study we focused on the impact of grazing on populations of the Skyros Wall lizard (Podarcis gaigeae), an endemic lacertid of Skyros Archipelago (Aegean Sea, Greece). Our aim was to detect and assess possible direct and/or indirect efects on several features of lizards’ overall biology. Five biotopes (three islets and two localities from Skyros Island) that difer in the duration and intension of grazing were included in the project. For a time-window of six years we realized monthly samplings during spring and summer (reproductive period of P. gaigeae) and recorded invertebrate population densities, lizard ectoparasites prevalence, presence and density of sea gulls and lizard population densities. As expected, grazing had a strong negative inluence on plant communities. The restriction of vegetation impoverished considerably invertebrate populations, decreasing thus food availability for lizards, which feed mainly on insects. Furthermore it resulted in a serious degradation of the biotope quality since lizards in islets use plants as shelters or thermoregulation sites. Ectoparasite loads (ticks and mites) were higher in places where goats were present in large numbers for long periods. Goat activity disturbs sea gulls that normally nest on remote islands. Islets where grazing was continuous hosted few or even none breeding pair. Since sea gulls support in terms of energy many islets of Skyros Archipelago through marine subsidies, the devastation of their breeding colonies afected negatively small insular ecosystems. Finally, population densities of lizards were higher in biotopes with no grazing (Diavates islet and the dunal ecosystem of Palamari at Skyros Island) and much lower in places with intense grazing.

×

Tail autotomy, the self‐induced tail separation from the body, is a common and effective antipredator mechanism in lizards. In this study, we examine the muscle energetics of tail shedding in six lacertid lizard species (Podarcis erhardii, Podarcis peloponnesiaca, Podarcis muralis, Podarcis gaigeae, Podarcis milensis, and Lacerta graeca) from the northeast Mediterranean region. Very long periods of postautotomy tail movement were demonstrated for all species ( min), and differences among species were not statistically significant. Postautotomy tail movement, powered by anaerobic muscle activity, resulted in a strong increase in lactate concentrations and a concomitant depletion of muscle glycogen of exhausted tails relative to resting tails. No significant differences were found in either lactate or glycogen concentrations among the species examined. Duration of movement was negatively correlated with final lactate concentrations. The lack of differentiation in postautotomy energetic physiology in this group of species that have evolved under very different predation environments indicates that postautotomy muscle metabolism involves an overall conservative suite of characters.

×

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.

×

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.

×

Wall lizards of the genus Podarcis (Sauria, Lacertidae) comprises 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 fall into four main groups that they have substantial geographic conherence (Western Island group, Southwestern group, Italian group and Balkan group). The Balkan species, is divided in two subgroups, the subgroup of P. taurica, P. milensis, P. gaigeae, P. melisellensis and the subgroup of P. erhardi and P. peloponnesiaca, which are highly diversified and present great morphological and ecological plasticity, inhabiting many different ecotypes. We address the question of phylogenetic relations among the species of the Podarcis taurica subgroup encountered in Greece, as they can be inferred from partial mtDNA (cyt b and 16S) and nuclear (c-mos) sequences. Our data suggest that P. gaigeae is closely related to P. milensis and both P. gaigae and P. milensis to P. taurica. However the specimens of P. taurica are subdivided in two different groups. The first includes the specimens from Russia and Northeastern Greece and the other the specimens from the rest of continental Greece and Ionian Islands. This result suggests that the evolutionary history of P. taurica in Greece is more complex than a single evolutionary invasion. The data analyzed 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 specific but mostly the sub- specific level of this genus.

×

Wall lizards of the genus Podarcis (Sauria, Lacertidae) comprise 17 currently recognized species in southern Europe, where they are the predominant nonavian 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, southwestern group, Italian group, and Balkan Peninsula group). The Balkan Peninsula species are divided into 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. pelo- ponnesiaca). In the present study, the question of phylogenetic relationships among the species of Podarcis encountered in the Balkan Peninsula was addressed using partial mtDNA sequences for cytochrome b (cyt b) and 16S rRNA (16S). The data support the mono- phyly of Podarcis and suggest that there are three phylogenetic clades: the clade A (P. taurica, P. gaigeae, P. milensis, and P. melisell- ensis); the clade B (P. erhardii and P. peloponnesiaca), and the clade C (P. muralis and P. sicula). By examining intraspeciWc relationships it was found that extant populations of P. erhardii are paraphyletic. Furthermore, subspecies previously deWned on the basis of morphological characteristics do not correspond to diVerent molecular phylogenetic clades, suggesting that their status should be reconsidered. The distinct geographic distribution of the major clades of the phylogenetic tree and its topology suggest a spatial and temporal sequence of phylogenetic separations that coincide with some major paleogeographic separations during the geological history of the Aegean Sea. The results stress the need for a reconsideration of the evolutionary history of Balkan Podarcis species and help overcome diYculties that classical taxonomy has encountered at both the species and subspecies level.

×

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. pelopon- nesiaca ). 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 his- tory of Greek Podarcis species and help overcome difficulties that classical taxonomy has encountered at both the species level.

×

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.

×

The Balkan Peninsula constitutes a biodiversity hotspot with high levels of species richness and endemism. The complex geological history of the Balkans in conjunction with the climate evolution are hypothesized as the main drivers generating this biodiversity. We investigated the phylogeography, historical demography, and popula- tion structure of closely related wall-lizard species from the Balkan Peninsula and southeastern Europe to better understand diversification processes of species with limited dispersal ability, from Late Miocene to the Holocene. We used several analytical methods integrating genome-wide SNPs (ddRADseq), microsatellites, mitochondrial and nuclear DNA data, as well as species distribution modelling. Phylogenomic analysis resulted in a completely resolved species level phylogeny, population level analyses confirmed the existence of at least two cryptic evolutionary lineages and extensive within species genetic structuring. Divergence time estimations indicated that the Messinian Salinity Crisis played a key role in shaping patterns of species divergence, whereas in- traspecific genetic structuring was mainly driven by Pliocene tectonic events and Quaternary climatic oscillations. The present work highlights the effectiveness of utilizing multiple methods and data types coupled with extensive geographic sampling to uncover the evolutionary processes that shaped the species over space and time.

×

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.

×

Ectotherms are vastly affected by climatic conditions as they rely on external sources of heat to regulate their body temperature, and changes in their habitat thermal quality could seriously affect their overall biology. To overcome the problems of a thermally unfavorable habitat, lizards need to either adjust their thermoregulatory behavior or respond to directional selection and shift their preferred body temperatures. To assess the impact of habitat thermal quality on the thermoregulatory profile, we studied multiple islet and ‘mainland’ populations of the Skyros wall lizard Podarcis gaigeae, an endemic lacertid to Skyros Archipelago, Greece. We evaluated the effectiveness of thermoregulation (E) using the three main thermal parameters: body (Tb), operative (Te), and preferred (Tpref) temperatures. We first hypothesized that the spatial homogeneity, the scarcity of thermal shelters, and the exposure to higher winds on islets would result in more demanding climate conditions. Second, we anticipated that islet lizards would achieve higher E in response to the lower thermal quality therein. As hypothesized, thermal parameters differed between populations but not in the expected manner. Skyros ‘mainland’ habitats reached higher temperatures, had more intense fluctuations, and were of lower thermal quality. As a result, lizards showed higher accuracy, precision, and effectiveness of thermoregulation. Noteworthy, we found that lizards from different populations have shifted their thermal profile and preferred body temperatures to cope with the particular conditions prevailing in their habitats. The latter supports the labile view on the evolution of thermoregulation.

×

The evolution of striking phenotypes on islands is a well-known phenomenon, and there has been a long-standing debate on the patterns of body size evolution on islands. The ecological causes driving divergence in insular populations are, however, poorly understood. Reduced predator fauna is expected to lower escape propensity, increase body size and relax selection for crypsis in small-bodied, insular prey species. Here, we investigated whether escape behaviour, body size and dorsal coloration have diverged as predicted under predation release in spatially replicated islet and mainland populations of the lizard species Podarcis gaigeae. We show that islet lizards escape approaching observers at shorter distances and are larger than mainland lizards. Additionally, we found evidence for larger between-population variation in body size among the islet populations than mainland populations. Moreover, islet populations are significantly more divergent in dorsal coloration and match their respective habitats poorer than mainland lizards. These results strongly suggest that predation release on islets has driven population divergence in phenotypic and behavioural traits and that selective release has affected both trait means and variances. Relaxed predation pressure is therefore likely to be one of the major ecological factors driving body size divergence on these islands.

×

When sexually selected traits diverge because of different local selective environments, premating isolation might arise as a correlated response. However, sexually selected traits might also diverge by stochastic forces. Here, we show that odour-based mate preferences and scent composition have diverged between islet- and mainland populations of Skyros wall lizard, Podarcis gaigeae. We quantified the degree of scent-mediated premating isolation between populations. Islet lizards preferred scent from islet lizards, whereas the mainland populations were less discriminatory. The pheromone compositions differed more between islets than between islet- and mainland populations and did not differ significantly between mainland populations. There was a tendency for population divergence in pheromones to be positively correlated with neutral genetic divergence. This might indicate a role for genetic drift in evolutionary change in these signals and partial decoupling between signals and preferences. Our results suggest that chemical signals and associated mate preferences can diverge through stochastic and selective forces and influence premating isolation.

×

Sexually selected traits are often condition-dependent and are expected to be affected by genome-wide distributed deleterious mutations and inbreeding. However, sexual selection is a powerful selective force that can counteract inbreeding through purging of deleterious mutations. Inbreeding and purging of the inbreeding load for sexually selected traits has rarely been studied across natural populations with different degrees of inbreeding. Here we investigate inbreeding effects (measured as marker-based heterozygosity) on condition-dependent sexually selected signalling trait and other morphological traits across islet- and mainland populations (n = 15) of an endemic lizard species (Podarcis gaigeae). Our data suggest inbreeding depression on a condition-dependent sexually selected signalling character among mainland subpopulations with low or intermediate levels of inbreeding, but no sign of inbreeding depression among small and isolated islet populations despite their higher overall inbreeding levels. In contrast, there was no such pattern among ten other morphological traits which are primarily naturally selected and presumably not involved in sexual signalling. These results are in line with purging of recessive deleterious alleles, or purging in combination with stochastic fixation of alleles by genetic drift, for a sexual signalling character in the islet environment, which is characterized by low population sizes and strong sexual selection. Higher clutch sizes in islet populations also raise interesting questions regarding the possibility of antagonistic pleiotropy. Purging and other non-exclusive explanations of our results are discussed.

×

Background: Patterns of spatial variation in discrete phenotypic traits can be used to draw inferences about the adaptive significance of traits and evolutionary processes, especially when compared to patterns of neutral genetic variation. Population divergence in adaptive traits such as color morphs can be influenced by both local ecology and stochastic factors such as genetic drift or founder events. Here, we use quantitative color measurements of males and females of Skyros wall lizard, Podarcis gaigeae, to demonstrate that this species is polymorphic with respect to throat color, and the morphs form discrete phenotypic clusters with limited overlap between categories. We use divergence in throat color morph frequencies and compare that to neutral genetic variation to infer the evolutionary processes acting on islet- and mainland populations. Results: Geographically close islet- and mainland populations of the Skyros wall lizard exhibit strong divergence in throat color morph frequencies. Population variation in throat color morph frequencies between islets was higher than that between mainland populations, and the effective population sizes on the islets were small (Ne:s < 100). Population divergence (FST) for throat color morph frequencies fell within the neutral FST-distribution estimated from microsatellite markers, and genetic drift could thus not be rejected as an explanation for the pattern. Moreover, for both comparisons among mainland-mainland population pairs and between mainland-islet population pairs, morph frequency divergence was significantly correlated with neutral divergence, further pointing to some role for genetic drift in divergence also at the phenotypic level of throat color morphs. Conclusions: Genetic drift could not be rejected as an explanation for the pattern of population divergence in morph frequencies. In spite of an expected stabilising selection, throat color frequencies diverged in the islet populations. These results suggest that there is an interaction between selection and genetic drift causing divergence even at a phenotypic level in these small, subdivided populations.

×

Allopatry and allopatric speciation can arise through two different mechanisms: vicariance or colonization through dispersal. Distinguishing between these different allopatric mechanisms is difficult and one of the major challenges in biogeographical research. Here, we address whether allopatric isolation in an endemic island lizard is the result of vicariance or dispersal. We estimated the amount and direction of gene flow during the divergence of isolated islet populations and subspecies of the endemic Skyros wall lizard Podarcis gaigeae, a phenotypically variable species that inhabits a major island and small islets in the Greek archipelago. We applied isolation-with-migration models to estimate population divergence times, population sizes and gene flow between islet-mainland population pairs. Divergence times were significantly correlated with independently estimated geological divergence times. This correlation strongly supports a vicariance scenario where islet populations have sequentially become isolated from the major island. We did not find evidence for significant gene flow within P. g. gaigeae. However, gene-flow estimates from the islet to the mainland populations were positively affected by islet area and negatively by distance between the islet and mainland. We also found evidence for gene flow from one subspecies (P. g. weigandi) into another (P. g. gaigeae), but not in the other direction. Ongoing gene flow between the subspecies suggests that even in this geographically allopatric scenario with the sea posing a strong barrier to dispersal, divergence with some gene flow is still feasible.

×

Although rapid evolution of body size on islands has long been known, the ecological mechanisms behind this island phenomenon remain poorly understood. Diet is an important selective pressure for morphological divergence. Here we investigate if selection for novel diets has contributed to the multiple independent cases of island gigantism in the Skyros wall lizard (Podarcis gaigeae) and if diet, predation, or both factors best explain island gigantism. We combined data on body size, shape, bite force, and realized and available diets to address this. Several lines of evidence suggest that diet has contributed to the island gigantism. The larger islet lizards have relatively wider heads and higher bite performance in relation to mainland lizards than would be expected from size differences alone. The proportions of consumed and available hard prey are higher on islets than mainland localities, and lizard body size is significantly correlated with the proportion of hard prey. Furthermore, the main axis of divergence in head shape is significantly correlated with dietary divergence. Finally, a model with only diet and one including diet and predation regime explain body size divergence equally well. Our results suggest that diet is an important ecological factor behind insular body size divergence, but could be consistent with an additional role for predation.

×

We will present data on pre-mating isolation between island populations and mainland populations of Skyros wall lizard, Podarcis gaigeae, using interest in chemical cues from the other sex as a proxy for mate preferences. Skyros wall lizard exhibit substantial morphological divergence in island populations within only a few hundred meters from the mainland source populations. Island gigantism has evolved at least twice, indicating that parallel ecological selection pressures are causing phenotypic divergence. This makes Skyros wall lizard an interesting model system for studying population divergence and speciation mechanisms. We have also detetected pronounced between-population differences in feeding structure from geometric morphometrics study of the skull. Differences in feeding structure are likely to be correlated with local diets, since a higher, shorter head-shape in lizards correspond to an increase in bite-force. Molecular genetic data from 10 microsatellite loci revealed that the island populations are much more diverged from each other and from the mainland populations, than the mainland populations are from each other. Reduction in gene flow could presumably have facilitated local adaptation in morphology and behavior on the islets.

×

Sexual selection is often viewed as a promoter of population divergence, but some forms of sexual selection could rather hamper divergence. Here, we investigate if sexual selection promotes divergence in sexually selected traits. We studied population variation in sexual selection in relation to colour morph and body size in islet and mainland populations of the Skyros wall lizard (Podarcis gaigeae). Females were most likely to mate with orange-throated males with small body sizes, and male body size and colouration were therefore subject to correlational sexual selection. In contrast, male mating probabilities were not affected by any female phenotypic character. We also found variation in a female resistance trait (escape propensity), with females being more prone to escape when exposed to males from other habitats. Sexual selection could potentially affect the frequencies of throat colour morphs in this species by favouring orange throated males of small body size, but there was no evidence of sexual selection for local mates or rare phenotypes. Our results do thus not support a role for sexual selection as a promoter of population divergence in this species.

×

Tissue regeneration is a fundamental evolutionary adaptation, which is well known in lizards that can regenerate their entire tail. However, numerous parameters of this process remain poorly understood. Lizard tail serves many functions. Thus, tail autotomy comes with many disadvantages and the need for quick regeneration is imperative. To provide the required energy and materials for caudal tissue building, lizards are expected to undergo a number of physiological and biochemical adjustments. Previous research showed that tail regeneration induces changes in the digestive process. Here, we investigated if and how tail regeneration affects the digestive performance in five wall lizard species deriving from mainland and island sites and questioned whether the association of tail regeneration and digestion is affected by species relationships or environmental features, including predation pressure. We expected that lizards from high predation environments would regenerate their tail faster and modify accordingly their digestive efficiency, prioritizing the digestion of proteins; the main building blocks for tissue repair. Second, we anticipated that the general food shortage on islands would inhibit the process. Our findings showed that all species shifted their digestive efficiency, as predicted. Elongation rate was higher in sites with stronger predation regime and this was also applied to the rate with which protein digestion raised. Gut passage time increases during regeneration so as to improve the nutrient absorbance, but among the islanders, the pace was more intense. The deviations between species should be attributed to the different ecological conditions prevailing on islands rather than to their phylogenetic relationships.

×

Body size shapes the overall biology of organisms. We assessed the impact of size on temperature regulation in populations of normal-sized and large-bodied insular Mediterranean lizards (Podarcis gaigeae, Lacertidae). We hypothesized that large lizards would achieve higher body temperatures and thermoregulate more effectively than their smaller kin. Large- and small-bodied lizards share the same thermoregulation pattern, achieving similar body temperatures in the field. Large lizards, however, prefer higher set-point temperatures. Lizards in both populations thermoregulate effectively, but large lizards thermoregulated less effectively than normal-sized lizards. The particular conditions at the islet that harbors the large-bodied population (harsh intraspecific competition) seem to account for this pattern.

×

The ability of vertebrates to evolve different defence strategies in response to varying parasitism regimes remains poorly understood. Hosts may adopt two different strategies to defend themselves against parasites: tolerance (hosts alleviate the negative fitness consequences of parasite infection) and resistance (hosts strengthen their immune response as parasite burden increases). Both strategies are effective, but fitness has been reported to decline faster in less-tolerant individuals. Here, we assessed the number of splenocytes and the cell-mediated response (proxies for resistance) and body condition (a proxy for tolerance) in four populations of a Greek endemic lizard (Podarcis gaigeae), each exposed to different infection risks (defined as the cumulative effect of parasite burden and duration of exposure). We anticipated that populations with heavy parasite burden would enhance the efficacy of their immune response (resistance) compared to lizards deriving from parasite-poor habitats. We also predicted that populations with longer exposure to parasites would be adopted and be more tolerant. Each factor (duration of exposure and parasite burden) had a distinct effect on the immune response, and thus, our results were rather complicated. Lizards with heavy parasite burden and aperiodic exposure demonstrated resistance, whereas lizards with heavy parasite burden and chronic exposure were more tolerant. Populations with low parasite burden and minimal exposure were more resistant. Our results suggest that the development of some immunological strategies may be differentiated under different infection risks, even within the same species.

×

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.

×

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.

×

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).

×

Most recent molecular studies revealed the phylogeny of Greek Podarcis species, which for years remained elusive, due to discordant data produced from various chromosomal, complement fixation and protein studies. In this report, we analyzed cellular immune responses of spleen- derived lymphocytes from six allopatric Podarcis species encountered in Greece, by assessing two-way mixed lymphocyte reaction (MLR)- induced proliferation. On the basis of stimulation indices (S.I.) as determined from cultures set up from xenogeneic splenocytes coincubated in pairs, we generated a phylogenetic tree, fully consistent with the phylogenetic relationships of Podarcis as determined by parallel analyses based on partial mitochondrial (mt) DNA sequences. Although the exact mechanisms triggering lymphocyte responses in lizard two-way xenogeneic MLR are not fully understood, our results show the potential use of cell-mediated immune responses as an additional approach to mtDNA analysis, for species delimitation within specific lizard taxa.

×

Fifteen polymorphic markers were developed from a microsatellite-enriched library for the lizard Podarcis gaigeae. The loci were checked for variability in 68 individuals from a population on the island of Skyros, Greece. The number of alleles ranged from 3 to 23 per locus and expected heterozygosity from 0.29 and 0.94. Most markers were also polymorphic in three closely related Podarcis species, namely P. erhardi, P. taurica and P. milensis. The markers will be used to examine gene flow and differentiation of island and mainland populations of P. gaigeae.