DNA metabarcoding the diet of Podarcis lizards endemic to the Balearic Islands

Dietary studies are essential to unravel the functioning of ecosystems and ultimately to understand biodiversity.This task,which at first may seem simple,becomes especially complex in those cases of omnivorous species with highly variable diets.In this regard,the emergence of next-generation DNA sequencing methodologies represents a powerful tool to address the problem.Here we implement a high-throughput metabarcoding strategy based on the analysis of four molecular markers aimed at sequencing both mitochondrial(animal prey)and chloroplast(diet plants)genome fragments from fecal samples of two lizard species endemic to the Balearic Archipelago(Podarcis lilfordi and P.pityusensis)obtained through non-invasive methods.The results allowed for the characterization of their diets with a high degree of taxonomic detail and have contributed a large number of new trophic records.The reported diets are based mainly on the consumption of arthropods,mollusks and plants from a diversity of taxonomic orders,as well as carrion and marine subsidies.Our analyses also reveal inter-and intra-specific differences both in terms of seasonality and geographical distribution of the sampled lizard populations.These molecular findings provide new insights into the trophic interactions of these threatened endemic lizards in their unique and isolated ecosystems.

An integrated assessment of a group with complex systematics: the Iberomaghrebian lizard genus Podarcis (Squamata, Lacertidae)

A critical review of the evolutionary biology of Iberian and North African lizard members of the genus Podarcis(Lacertidae)based on phylogeny,phylogeography,morphometrics,behavior,ecology and physiology is presented.The Iberomaghrebian region is inhabited by at least 12 different evolutionary lineages that group into a monophyl-etic clade(except Podarcis muralis).In contrast to the current taxonomy,the saxicolous‘Podarcis hispanica’is paraphyletic with respect to Podarcis bocagei and Podarcis carbonelli,two currently recognized species.Nodes in the phylogenetic tree are deep,resulting from old divergences,clearly preceding the Pleistocene.Nevertheless,more recent range changes as a result of glaciations are also evident.The most plausible evolutionary scenario for this group indicates both vicariant and dispersal events.Although parapatry between lineages is the rule,sympatry and even syntopy are frequent,but usually between ground-dwelling and saxicolous forms.Contacts between forms with similar habitat use are rare and local.Morphological distinctiveness between lineages has been demonstrated,indicating historical constraints.However,other characters have repeatedly evolved under similar environmental pressures independently of the evolutionary lineage.Strong sexual dimorphism derives from sexual selection and is attained before sexual maturity,although developmental restrictions exist.Variation between popu-lations is also important and derives from local variation in both natural(habitat,climate)and sexual(density)selective pressures.Evidence for short-term changes has already been found,particularly in insular populations.Reproductive isolation between syntopic forms and partner recognition are based on male–male competition and on visual and chemical recognition of females by conspecific males.Despite this ancient diversification,most forms maintain a degree of reproductive compatibility.Hybridisation may occur,but is limited,and there is evidence of selection against hybrids.The ecological analysis presented here does not support exploitative competition,but rather behavioral interference between forms.Ecomorph classification of lineages suggests character displacement between those with extensive range overlap.Finally,a critical assessment of the specific status of all lineages is provided and directions for further research are suggested.

Smarter in the city?Lizards from urban and semi-natural habitats do not differ in a cognitive task in two syntopic species

Urbanization occurs at a global scale,imposing dramatic and abrupt environmental changes that lead to biodiversity loss.Yet,some animal species can handle these changes,and thrive in such artifcial environments.One possible explanation is that urban individuals are equipped with better cognitive abilities,but most studies have focused on birds and mammals and yielded varied results.Reptiles have received much less attention,despite some lizard species being common city dwellers.The Italian wall lizard,Podarcis siculus,and the common wall lizard,Podarcis muralis,are two successful lizards in anthropogenic habitats that thrive in urban locations.To test for differences in a cognitive skill between urban and semi-natural environments,we investigated inhibitory control through a detour task in syntopic populations of the two species,across 249 lizards that were tested in partially artifcial feld settings.Sophisticated inhibitory control is considered essential for higher degrees of cognitive fexibility and other higher-level cognitive abilities.In this task,we confronted lizards with a transparent barrier,separating them from a desired shelter area that they could only reach by controlling their impulse to go straight and instead detour the barrier.We found no differences between lizards in urban and semi-natural environments,nor between species,but females overall performed better than males.Moreover,48%of the lizards in our study did not perform a correct trial in any of the 5 trials,hinting at the diffculty of the task for these species.This study is among the frst to address lizard cognition,through their inhibitory control,as a potential explanation for success in cities and highlights one should be careful with assuming that urban animals generally have enhanced cognitive performance,as it might be taxa,task,or condition dependent.

Female mate choice based on pheromone content may inhibit reproductive isolation between distinct populations of Iberian wall lizards

The Iberian wall lizard Podarcis hispanica forms part of a species complex with several morphologically and geneti- cally distinct types and populations, which may or may not be reproductively isolated. We analyzed whether female mate choice based on males＇ chemical signals may contribute to a current pre-mating reproductive isolation between two distinct populations of P. hispanica from central Spain. We experimentally examined whether females choose to establish territories on areas scent-marked by males of their own population, versus areas marked by males of the other population. Results showed that fe- males did not prefer scent-marks of males from their own population. In contrast, females seemed to attend mostly to among-individual variation in males＇ pheromones that did not differ between populations. Finally, to test for strong premating re- productive isolation, we staged intersexual encounters between males and females. The population of origin of males and females did not affect the probability nor the duration of copulations. We suggest that the different environmental conditions in each population might be selecting for different morphologies and different chemical signals of males that maximize efficiency of communication in each environment. However, females in both populations based mate choice on a similar condition-dependent signal of males. Thus, male signals and female mate choice criteria could be precluding premating reproductive isolation between these phenotypically ＂distinct＂ populations [Current Zoology 59 （2）： 210-220, 2013].

Inter- and intra-population variability of the protein content of femoral gland secretions from a lacertid lizard

Femoral glands of male lizards produce waxy secretions that are involved in inter- and intraspecific chemical communication. The main components of these secretions are proteins and lipids, the latter having been extensively studied and already associated to male quality. On the opposite, the composition and role of proteins are nearly unknown, the only available information coming from few studies on iguanids. These studies got the conclusion that proteins might have a communicative function, notably they could signal individual identity. A generalization of these findings requires the extension of protein analysis to other lizard families, and the primary detection of some patterns of individual variability. Using the common wall lizard Podarcis muralis as a model species, the protein fraction of the femoral pore secretions was investigated to provide the first characterization of this component in a lacertid lizard and to explore its source of variability, as a first step to support the hypothesized communicative role. Samples of proteins from femoral secretions were collected from 6 Italian populations and subjected to 1-dimensional electrophoresis. The binary vector of the band presence/absence was used to define the individual profiles. Protein fraction is found to have a structured pattern, with both an individual and a population component. Although the former supports the potential communicative role of proteins, the latter offers a double interpretation, phylogenetic or environmental, even though the phylogenetic effect seems more likely given the climatic resemblance of the considered sites. Further studies are necessary to shed light on both these issues.

Trophic niche changes associated with the eradication of invasive mammals in an insular lizard: an assessment using isotopes

Invasive species are a major threat to island biodiversity,and their eradications have substantially contributed to the conservation of island endemics.However,the consequences of eradications on the trophic ecology of native taxa are largely unexplored.Here,we used the eradication of invasive black rats Rattus rattus and European rabbits Oryctolagus cuniculus from the Berlenga Island,in the western coast of Portugal,as a whole-ecosystem experiment to investigate the effects of the eradication of invasive mammals on the trophic niche and body dimensions of the island-restricted Berlenga wall lizard Podarcis carbonelli berlengensis over a 2-year period.Our results suggest an expansion of the isotopic niche and an intensification of the sexual dimorphism of the lizard following mammal eradication.Additionally,we found considerable variability in isotopic niche across the island and detected evidence of sex-specific and season-modulated nutritional requirements of this threatened reptile.Our findings support that the eradication of 2 of the planets most problematic invasive vertebrates led to changes in the lizard trophic niche and sexual dimorphism in just 2 years.This suggests that the ecological pressuresfor example,prey availability and habitat structureto which lizards are exposed have substantially changed post-eradication.Our study emphasizes the scientific value of island eradications as experiments to address a wide range of ecological questions and adds to the increasing body of evidence supporting substantial conservation gains associated with these restoration interventions.

Epistatic interactions between pterin and carotenoid genes modulate intra-morph color variation in a lizard

Color polymorphisms have become a major topic in evolutionary biology and substantial efforts have been devoted to the understanding of the mechanisms responsible for originating such colorful systems.Within-morph continuous variation,on the other hand,has been neglected in most of the studies.Here,we combine spectrophotometric/visual modeling and genetic data to study the mechanisms promoting continuous variation within categorical color morphs of Podarcis muralis.Our results suggest that intra-morph variability in the pterin-based orange morph is greater compared to white and yellow morphs.We also show that continuous variation within the orange morph is partially discriminable by conspecifics.Genotyping results indicate that allelic variants at the BCO2 locus(responsible for deposition of yellow carotenoids)contribute to generate continuous variation in orange individuals.However,other intrinsic and/or extrinsic mechanisms,such as body size,might be involved,opening a new avenue for future research on the drivers of continuous variation within-morphs.