The Columbretes archipelago consists of a group of small volcanic islets located in the western Mediterranean near the east of the Iberian Peninsula. Four of its islands are inhabited by the wall lizard Podarcis liolepis, whose populations have been considered vulnerable. The purpose of this study was to assess the level of genetic diversity across the archipelago and the possible evolutionary origin of the Columbretes lizard populations. Additionally, we investigated the evolutionary ecology of these populations using a DNA-based metabarcoding approach to characterise both their microbiota and trophic interactions. The genetic results reported very low genetic diversity and corroborated the conspecificity between insular populations and P. liolepis from the mainland (Peñagolosa region). The results of the metabarcoding analyses based on faecal samples were in accordance with an omnivorous ecology, suggesting that specific microbiota communities in the insular populations might be correlated with differences in host ecology and phylogeny. These results are a valuable contribution to the current understanding of the evolution of Columbretes’ lizards and provide important information for conservation management.
