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.

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.