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Simple Summary: Understanding individual variation in reproductive investment, such as the number and size of eggs a mother produces in a single clutch, is an important species characteristic with implications for resilience to environmental change and conservation. In this study, we aimed to identify the main determinants of female reproductive investment in an island lizard species that experiences different local selection pressures depending on island size and local conditions such as vegetation cover, food availability, and predator species. We found that the number of eggs produced by a female is not just a function of maternal size, but is also strongly shaped by the richness of the local predator community: lizard populations living on islands with the fewest predators showed a >50% reduction in clutch size, as well as corresponding reductions in clutch volume. Our results emphasize the importance of local ecological conditions on vertebrate reproductive investment. Reproductive investment, including the number of offspring produced, is one of the fundamental characteristics of a species. It is particularly important for island vertebrates, which face a disproportionate number of threats to their survival, because it predicts, among other things, a species' resilience to environmental disruption. Taxa producing more offspring recover more quickly from environmental perturbations and survive environmental change better. However, ecologists do not understand which primary drivers shape a species' reproductive investment well. Here, we compare the reproductive efforts of 14 island populations of the Aegean Wall Lizard (Podarcis erhardii), which lives across widely diverging environmental conditions. We test three hypotheses, namely that reproductive investment (measured as clutch size, clutch volume) is (1) positively associated with predation risk ['Predation Risk Hypothesis']; (2) positively associated with the presence of reliable vegetation cover that provides shelter ['Gravid Female Protection Hypothesis']; and (3) limited by (and hence positively correlated with) food availability ['Food Limitation Hypothesis']. Although field data are somewhat consistent with all three hypotheses, statistical analyses provide strong support for the Predation Risk Hypothesis. The results not only shed light on which fundamental forces shape reproductive investment in island vertebrates, but can also help shape conservation priorities. [ABSTRACT FROM AUTHOR]

Simple Summary: As ectotherms that do not produce metabolic heat to regulate their body temperature, lizards largely rely on the thermal quality of the environment for most aspects of their biology. To compensate for geographically induced changes in the thermal environment, different lizard populations within a single species should either regulate their behavior or shift their thermal preferences, responding to directional selection. Here, we studied the thermal ecology of the endemic Skyros wall lizard (Podarcis gaigeae) and assessed the influence of thermal habitat quality on body temperature and preferred body temperatures. Our findings suggest that the species thermoregulate effectively in a wide variety of habitats and support the view that the thermal characteristics of certain species are plastic and respond to environmental changes. 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. [ABSTRACT FROM AUTHOR]

Cognition is an essential tool for animals to deal with environmental challenges. Nonetheless, the ecological forces driving the evolution of cognition throughout the animal kingdom remain enigmatic. Large‐scale comparative studies on multiple species and cognitive traits have been advanced as the best way to facilitate our understanding of cognitive evolution, but such studies are rare. Here, we tested 13 species of lacertid lizards (Reptilia: Lacertidae) using a battery of cognitive tests measuring inhibitory control, problem‐solving, and spatial and reversal learning. Next, we tested the relationship between species' performance and (a) resource availability (temperature and precipitation), habitat complexity (Normalized Difference Vegetation Index), and habitat variability (seasonality) in their natural habitat and (b) their life history (size at hatching and maturity, clutch size, and frequency). Although species differed markedly in their cognitive abilities, such variation was mostly unrelated to their ecology and life history. Yet, species living in more variable environments exhibited lower behavioral flexibility, likely due to energetic constrains in such habitats. Our standardized protocols provide opportunities for collaborative research, allowing increased sample sizes and replication, essential for moving forward in the field of comparative cognition. Follow‐up studies could include more detailed measures of habitat structure and look at other potential selective drivers such as predation. [ABSTRACT FROM AUTHOR]

Animals exhibit considerable and consistent among-individual variation in cognitive abilities, even within a population. Recent studies have attempted to address this variation using insights from the field of animal personality. Generally, it is predicted that animals with "faster" personalities (bolder, explorative, and neophilic) should exhibit faster but less flexible learning. However, the empirical evidence for a link between cognitive style and personality is mixed. One possible reason for such conflicting results may be that personality–cognition covariance changes along ecological conditions, a hypothesis that has rarely been investigated so far. In this study, we tested the effect of habitat complexity on multiple aspects of animal personality and cognition, and how this influenced their relationship, in five populations of the Aegean wall lizard (Podarcis erhardii). Overall, lizards from both habitat types did not differ in average levels of personality or cognition, with the exception that lizards from more complex habitats performed better on a spatial learning task. Nevertheless, we found an intricate interplay between ecology, cognition, and personality, as behavioral associations were often habitat- but also year-dependent. In general, behavioral covariance was either independent of habitat, or found exclusively in the simple, open environments. Our results highlight that valuable insights may be gained by taking ecological variation into account while studying the link between personality and cognition. [ABSTRACT FROM AUTHOR]

Recently, biologists have become increasingly interested in cognitive variation among individuals and how it relates to differences in fitness. However, very few studies so far have studied the long-term repeatability and heritability of cognitive performance in wild animals. This is nevertheless crucial information to fully understand the potential ecological and evolutionary impact of individual variation in cognitive performance. In 2019, we assessed exploration, problem solving and spatial and reversal learning in 66 Aegean wall lizards, Podarcis erhardii , then released them in seminatural enclosures consisting of either simple or complex habitat. One year later, we recaptured and retested the surviving lizards and their offspring to estimate the long-term repeatability and heritability of these behavioural and cognitive characteristics. We found that exploration and spatial learning were moderately repeatable, but reversal learning only marginally and learning flexibility and problem solving not at all. Reversal learning ability declined over time in lizards kept in simple habitat, but not in those kept in complex habitats – suggesting habitat-dependent cognitive plasticity. To our knowledge, this is the first study demonstrating (long-term) consistency in cognitive traits within a nonavian reptile. The combination of modest repeatability and low heritability does suggest that, within our study species, personality and cognitive variation among individuals and populations is mostly moulded by environmental effects. • We tested repeatability and heritability of exploration and cognition in lizards. • Only exploration and spatial learning were moderately repeatable between years. • Reversal learning was marginally repeatable. • Lizards showed habitat-dependent changes in their reversal learning abilities. • Heritability estimates were low and nonsignificant. [ABSTRACT FROM AUTHOR]

Though biological invasions constitute one of the biggest threats for global biodiversity, our understanding of the mechanisms that enable invasive species to outperform native species is still limited, especially, in terms of behavior. Most available studies have examined behavioral traits which favor invasive species on the later stages of invasion, however, our knowledge on earlier stages, namely, when alien species face novel environments and must exploit new resources, remains obscure. Here, we focus on one crucial behavioral trait, finding food. The Italian wall lizard (Podarcis siculus) has been widely introduced and established viable populations in S. Europe and N. America. We examined whether P. siculus has enhanced exploratory behavior and abilities to find food compared to two native congeneric species with which it may come in contact in the near future, an insular endemic (P. milensis) and a widely distributed lizard (P. erhardii). We performed a Y-maze experiment, in which we varied arm markings in a standard way to prevent learning. Podarcis siculus was more efficient than its congenerics in finding and consuming food. This exploitative superiority was persistent, more frequent and repetitive. Interesting behavioral differences were also detected within the native species. Some P. milensis individuals showed no interest in exploring the maze, while few P. erhardii individuals remained rather indifferent to food even after detecting it. Our results suggest that the invasive P. siculus displays behavioral traits that could provide better opportunities for survival in the new environment and thus facilitate establishment even in the presence of congenerics. This provides further support to the idea that behavior plays a crucial role in animal invasions. [ABSTRACT FROM AUTHOR]

Harsh and variable environments have been hypothesized to both drive and constrain the evolution towards higher cognitive abilities and behavioural flexibility. In this study, we compared the cognitive abilities of island and mainland Aegean wall lizards (Podarcis erhardii), which were expected to live in respectively a more variable and a more stable habitat. We used four proxies of behavioural flexibility: a neophobia assay, a problem-solving test and a spatial + reversal learning task. Surprisingly, the two populations did not differ in neophobia or problem-solving. Insular lizards, however, outperformed mainland conspecifics in an initial spatial learning task, but were less successful during the subsequent reversal learning. Our results thus seem to indicate that the effect of environmental variability on cognition is complex, as it may favour some, but not all aspects of behavioural flexibility. [ABSTRACT FROM AUTHOR]

Animal signals are dynamic traits that can undergo considerable spatial and temporal changes and that are influenced by factors such as age, health condition and interactions with both the abiotic and biotic environment. However, much of our understanding of signal changes throughout an individual's lifetime stems from cross‐sectional, often laboratory‐based, studies focused on visual and auditory signals. Longitudinal field investigations of temporal variation in chemical signals, especially in vertebrates, remain rare despite chemical communication being the most ubiquitous form of information exchange in the natural world. To remedy this, we conducted a unique, replicated field experiment to study the temporal signal dynamics in free‐living lizard populations on natural islands. Specifically, we collected scent marks from individually marked lizards across five populations during the spring of two consecutive years and analysed the lipophilic chemical composition of these scent marks. Our findings demonstrate that the overall scent mark composition of individual lizards changed over time, shifting consistently in both direction and magnitude from year to year among individuals and across replicate populations. Similar patterns were observed for the chemical richness and diversity of scent marks. Temporal variation in the relative proportions of three potentially socially relevant signalling compounds in lizard scent marks revealed a more complex pattern: α‐tocopherol remained stable over time, oleic acid decreased and the change in octadecanoic acid proportion was body size‐dependent. Together, our results provide novel insights into how individual vertebrate chemical signals may fluctuate across space and time. We discuss the potential causes of the observed temporal variability and its consequences for chemical signal evolution. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The correct Table 1 is shown as follow: Table 1 Model building of the factors involved in the behavioural variables displayed by the three I Podarcis i species in the Y maze. Correction to: Invasive Italian wall lizards outcompete native congeneric species in finding food in a Y-maze The first Subtitle of Table 1 should be read "Success" not "First Correct Decision Time - Time to Decision Point". [Extracted from the article]

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Both environmental temperatures and spatial heterogeneity can profoundly affect the biology of ectotherms. In lizards, thermoregulation may show high plasticity and may respond to environmental shifts. In the context of global climate change, lizards showing plastic thermoregulatory responses may be favored. In this study, we designed an experiment to evaluate the extent to which lizard thermoregulation responds to introduction to a new environment in a snapshot of time. In 2014, we captured individuals of the Aegean Wall lizard (Podarcis erhardii) from Naxos Island (429.8 km2) and released them onto two small, lizard-free islets, Galiatsos (0.0073 km2) and Kampana (0.004 km2) (Aegean Sea, Greece). In 2017, we returned to the islets and estimated the effectiveness (E), accuracy and precision of thermoregulation measuring operative, preferred (T pref) and body temperatures. We hypothesized that the three habitats would differ in thermal quality and investigated the extent to which lizards from Naxos demonstrate plasticity when introduced to the novel, islet habitats. Thermal parameters did not differ between Galiatsos and Naxos and this was reflected in the similar E and T pref. However, lizards from Kampana deviated in all focal traits from Naxos, resulting in higher E and a preference for higher T pref. In sum, Naxos lizards shifted their thermoregulatory profile due to the idiosyncratic features of their new islet habitat. Our results advocate a high plasticity in lizard thermoregulation and suggest that there is room for effective responses to environmental changes, at least for Podarcis lizards in insular habitats. • We evaluate if and how quickly lizards may shift thermoregulatory patterns. • We introduced lizards on islets and 3 years later assessed their thermal profile. • One islet population deviated in all focal traits. • Thermal shifts are due to idiosyncratic features of the new habitat. • Lizards may effectively respond to environmental changes. [ABSTRACT FROM AUTHOR]

Studies on life history characters are of pivotal importance to understand population dynamics and demography and, if required, to propose effective conservation measures. The Balkan green lizard (Lacerta trilineata) is the most widespread lizard species in the Balkans but, interestingly, there are no studies on its reproductive biology. Herein, we focused on life history traits of L. trilineata, examining 369 museum specimens deriving from 12 island and 5 mainland populations from Greece. We measured the testicle size and the length of the epididymis in males, and the presence, number and size of oviductal eggs and vitellogenic follicles in females during activity seasons (from March to September). Our results suggest that the annual reproductive cycle in both sexes starts in mid-April and ends in July, though insular lizards seem to slightly prolong their reproductive season. Both sexes reached sexual maturity at a minimum body size of approximately 80 mm. Clutch size varied greatly depending on maternal body size. Clutch size and mean egg volume differed between mainland and island populations: in a striking deviation from the island syndrome, insular females carried more (13) but smaller eggs compared to their mainland conspecifics (nine but larger eggs). Mean egg volume was negatively correlated with clutch size. [ABSTRACT FROM AUTHOR]

Invasive species have been recognised as an important hazard to native communities. Amongst the mitigation measures that have been proposed to confront biological invasions, eradication projects are certainly the most drastic. In this short communication, a successful eradication project against a recently established population of the Italian wall lizard (Podarcis siculus) in Athens, Greece, is reported. To this aim, the Hellenic Herpetological Society received unforeseen aid from stray cats and, possibly, from the cellated skink (Chalcides ocellatus) and vegetation growth. Within three years, the initial thriving P. siculus population has shrunk to very few individuals. [ABSTRACT FROM AUTHOR]

In this study we aimed to clarify the identity of a wall lizard population that deviates phenotypically from the other Podarcis lizards that occur in the broader area (Athens, Greece). To this end we used molecular techniques. Most surprisingly, we identified the focal population as Podarcis vaucheri, a species far away from its natural range. Molecular results suggest an Iberian origin of this population. To the best of our knowledge, this is the first report of P. vaucheri outside its original range. The new population should be attributed to human-mediated introduction. The future interaction of this introduced species with native lizards, many of which are endemic to Greece, is of critical importance. [ABSTRACT FROM AUTHOR]

Abstract: The signals that animals use to communicate often differ considerably among species. Part of this variation in signal design may derive from differential natural selection on signal efficacy; the ability of the signal to travel efficiently through the environment and attract the receiver's attention. For the visual and acoustic modalities, the effect of the physical environment on signal efficacy is a well‐studied selective force. Still, very little is known on its impact on chemical signals. Here, we took a broad, phylogenetic comparative approach to test for a relationship between animals' signal chemistry and properties of their natural environment. Our study focused on lizards from the Lacertidae family. We sampled 64 species across three continents and determined the lipophilic composition of their glandular signalling secretions using gas chromatography–mass spectrometry. For each species, an array of environmental variables of high temporal and spatial resolution was obtained from climate databases. Species varied considerably in the overall richness (number of constituents) of their secretions, as well as in the relative contribution of the major chemical compound classes. Signal richness and the relative contribution of the respective compounds exhibited little evidence of phylogenetic relatedness, suggesting that chemical signals may change very rapidly. Neither insularity nor substrate use affected chemical signal composition, however, we found a strong statistical relationship between the chemistry of the lizards' secretions and aspects of the thermal and hydric environment they inhabit. Species from ‘xeric’ milieus contained high proportions of stable fatty acid esters and high molecular weight alcohols in their glandular secretions, which likely increase the persistence of secretion scent‐marks. In contrast, species inhabiting ‘mesic’ environments produced secretions of a high chemical richness comprising high levels of aldehydes and low molecular weight alcohols. This chemical mix probably creates a volatile‐rich signal that can be used for long‐distance airborne communication. We argue that the observed variation in signal design results from differential natural selection, optimizing signal efficacy under contrasting environmental conditions. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

Parasites are ubiquitous in wildlife populations and are regularly present in free-ranging vertebrates. Little research has been done on the impact of insularity on the patterns of parasitism. Islands, known for low genetic diversity and poor parasitic infracommunities, offer a tractable model to better understand the factors that shape parasitism. This study analyses helminth parasite loads from eight populations of the Erhard's Wall lizard (Podarcis erhardii, Lacertidae) occurring on islands of varying size, age and isolation in the Aegean Sea (Greece). By comparing burdens of infection among the different populations, we aimed to elucidate how island features shape levels of parasitism. Parasite communities on the islands were very species-poor, with only four genera of nematodes (Spauligodon sp., Skrjabinodon sp., Parapharyngodon sp. and Skrjabinelazia sp.) detected among the lizard populations. We found that aggregate worm infection level was positively correlated with island area, whereas total parasite prevalence was negatively correlated with island age, though marginally. This suggests that numbers of parasites are determined by the loss of genetic diversity as consequence of long-term population bottlenecks. Given that the island populations constitute an important model for the effects of habitat fragmentation on biodiversity, our findings raise concerns about the long-term prospects for many specialized parasite populations in the face of widespread anthropogenic habitat fragmentation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Temperature affects all aspects of reptilian biology. In order to colonize new habitats and support viable populations lizards have to successfully deal with their thermal environment. Podarcis siculus is a notorious example of a successful colonizer that has invaded numerous habitats outside its natural distribution range. Though certain features of its thermal biology have been assessed so far, the thermoregulatory abilities of the species remain poorly described. Here we investigated a recently discovered population in Greece and evaluated the effectiveness of thermoregulation measuring three main thermal parameters: set-point range, operative and field body temperatures. The Greek P. siculus appear to be accurate, precise and effective thermoregulators achieving E = 0.96. This effective thermoregulation may be used to explain, among other special characteristics, its spreading success. [ABSTRACT FROM AUTHOR]

Environmental temperatures considerably affect the reptilian ability for thermoregulation and harsh climatic conditions may impose a highly effective body temperature regulation to lizards. Such demanding 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 =0.91, d e ¯ − d b ¯ =7.6). This high effectiveness comes to compensate living in an inhospitable habitat as the operative temperatures denote (d e =7.79). 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. [ABSTRACT FROM AUTHOR]

PurposeDuring the last three decades, the number of devices that emit non-ionizing electromagnetic radiation (EMR) at the wireless communication spectrum has rapidly increased and possible effects on living organisms have become a major concern. The purpose of this study was to investigate the effects of radiofrequency EMR emitted by a widely used wireless communication device, namely the Digital Enhanced Communication Telephony (DECT) base, on the immune responses of the Aegean wall lizard (Podarcis erhardii). Materials and methodsAdult male lizards were exposed 24 h/day for 8 weeks to 1880–1900 MHz DECT base radiation at average electric field intensity of 3.2 V/m. Immune reactivity was assessed using the phytohemagglutinin (PHA) skin swelling and mixed lymphocyte reaction (MLR) tests. ResultsOur results revealed a noticeable suppression (approximately 45%) of inflammatory responses in EMR-exposed lizards compared to sham-exposed animals. T cell-mediated responses were marginally affected. ConclusionDaily radiofrequency EMR exposure seems to affect, at least partially, the immunocompetence of the Aegean wall lizard. [ABSTRACT FROM AUTHOR]

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 intramale aggressiveness confer two great advantages to cannibals: food and elimination of future rivals. [ABSTRACT FROM AUTHOR]

Organisms generally have many defenses against predation, yet may lack effective defenses if from populations without predators. Evolutionary theory predicts that 'costly' antipredator behaviors will be selected against when predation risk diminishes. We examined antipredator behaviors in Aegean wall lizards, Podarcis erhardii, across an archipelago of land-bridge islands that vary in predator diversity and period of isolation. We examined two defenses, flight initiation distance and tail autotomy. Flight initiation distance generally decreased with declining predator diversity. All predator types had distinctive effects on flight initiation distance with mammals and birds having the largest estimated effects. Rates of autotomy observed in the field were highest on predator-free islands, yet laboratory-induced autotomy increased linearly with overall predator diversity. Against expectation from previous work, tail autotomy was not explained solely by the presence of vipers. Analyses of populations directly isolated from rich predator communities revealed that flight initiation distance decreased with increased duration of isolation in addition to the effects of current predator diversity, whereas tail autotomy could be explained simply by current predator diversity. Although selection against costly defenses should depend on time with reduced threats, different defenses may diminish along different trajectories even within the same predator-prey system. [ABSTRACT FROM AUTHOR]

Caudal autotomy, the self-induced tail shedding from the body, is a common defensive strategy in lizards. Tail loss is followed rapidly by regeneration, revealing the importance of a fully functional tail. Predation pressure has been traditionally correlated with autotomy performance. However there is a lack of evidence regarding the impact of predation regime on tail regeneration. Another important factor that has been neglected is the population density. Though it is well established that crowding alters various life-history traits, the impact of density on caudal regeneration remains understudied. In this paper we compared three island populations of the Aegean Wall Lizard (Podarcis erhardii) that have evolved under different levels of predation pressure: whereas the Naxos population is exposed to numerous predators the Kopries and Daskalio islet populations experience low predation pressure. To evaluate the effect of density-induced stress on caudal regeneration, lizards were treated under two conditions of housing, in single and crowded (six individuals) terraria. Tail sheding occurred prior to this treatment following a standardised method. The length of regenerated tail was recorded weekly. Regeneration rate was higher in single terraria when compared to crowded, reflecting the negative impact of crowding. However we failed to detect any statistically significant difference between single and crowded terraria in the case of Naxos. We believe that the underlying reason must be the heavy predation pressure under which rapid tail regeneration, even under unfavourable conditions, is crucial for survival. It seems that the imperious need for regeneration counteracts density-induced stress. [ABSTRACT FROM AUTHOR]

The article reports on an instance of extreme toe morphology in Podarcis erhardii.

A preface for the November 2009 issue of "Amphibia-Reptilia" is presented.

Space is a limited resource in which many animals need to perform basic functions such as feeding and reproducing. Competition over access to space can induce a variety of behaviours that may result in differential access to crucial resources related to survival and fitness. The Aegean wall lizard, Podarcis erhardii , is a colour-polymorphic lizard that inhabits dry stone walls where they access food, safely thermoregulate, shelter from predators and interact with other lizards. Many colour-polymorphic species have morphs with distinct behavioural strategies, which may play a role in morph evolution and maintenance. Here, we conducted the first behavioural experiments on P. erhardii colour morphs. Our goal was to compare morph competitive ability and characterize morph differences in social behaviours using laboratory contest experiments over limited heated space on a stone wall in a neutral arena. Contest experiments revealed that colour morph, not size, predicted intermorph contest outcomes. White and yellow morphs were associated with winning and the orange morph was associated with losing contests. Male colour morphs exhibited different levels of aggressive, boldness, chemical signalling and visual signalling behaviours depending on which morph they were in contest with. White morphs always performed aggressive and scent-marking behaviours more frequently during contests with other morphs. Yellow morphs performed aggressive, bold, chemical signalling and visual signalling behaviours at intermediate frequencies relative to other morphs. Orange morphs performed aggressive behaviours equally often when in contest with yellow morphs but performed all other behaviours less frequently against yellow and white morphs. Considering these results, behavioural variation among P. erhardii colour morphs may promote morph maintenance. • Male lizard colour morphs differed in their ability to win staged contests for space. • White and yellow morphs were associated with winning contests over space. • Larger orange morphs were associated with losing and were the least aggressive. • White morphs were the most aggressive and scent-marked territories often. • Different social strategies among morphs may help maintain polymorphism. [ABSTRACT FROM AUTHOR]

The ability for effective, accurate and precise thermoregulation is of paramount importance for ectotherms. Sympatric lizards often partition their niche and select different microhabitats. These microhabitats, however, usually differ in their thermal conditions and lizards have to adapt their thermoregulation behavior accordingly. Here, we evaluated the impact of habitat partitioning on the thermal biology of three syntopic, congeneric lacertids ( Podarcis peloponnesiacus , P. tauricus and P. muralis ) from central Peloponnese, Greece. We assessed thermoregulation effectiveness ( E ) using the three standard thermal parameters: body ( T b ), operative ( T e ) and preferred ( T pref ) temperatures. We hypothesized that the microhabitats used by each species would differ in thermal quality. We also predicted that all species would effectively thermoregulate, as they inhabit a thermally challenging mountain habitat. As expected, the partition of the habitat had an effect on the thermoregulation of lizards since microhabitats had different thermal qualities. All three species were effective and accurate thermoregulators but one of them achieved smaller E values as a result of the lower T b in the field. This discrepancy could be attributed to the cooler (but more benign) thermal microhabitats that this species occupies. [ABSTRACT FROM AUTHOR]

Temperature rules the lives of ectotherms. To perform basic biological functions, ectotherms must make behavioral adjustments to keep their body temperatures near a preferred temperature (Tpref). Many color polymorphic lizards are active thermoregulators and exhibit morph differences in traits related to thermoregulation, such as color, body size, and microhabitat use. The Aegean wall lizard, Podarcis erhardii , is a heliothermic lizard with orange, white, and yellow color morphs that differ in size, behavior, and microhabitat use. Here, we tested whether P. erhardii color morphs from the same population from Naxos island, Greece, differ in Tpref. We hypothesized that orange morphs would prefer lower temperatures than white and yellow morphs because orange morphs are often found on cooler substrates and in microhabitats with more vegetation cover. We obtained Tpref for 95 individuals using laboratory thermal gradient experiments of wild-caught lizards and found that orange morphs do, indeed, prefer cooler temperatures. Average orange morph Tpref was 2.85 °C lower than average white and yellow morph Tpref. Our results add support to the idea that P. erhardii color morphs have multivariate alternative phenotypes and present the possibility that thermally heterogeneous environments play a role in the maintenance of color polymorphism in this species. • Color morphs in Aegean wall lizards (Podarcis erhardii) are either orange, white, or yellow. • Color morphs use different microhabitat: orange morphs are often found in shady, cooler environments. • We used thermal gradient experiments to determine whether color morphs prefer different temperatures. • We found that white and yellow color morphs prefer hotter temperatures (+2.85 °C) compared to the orange morph. • Availability of thermally heterogeneous habitat may play a role in color morph persistence. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]