Wall lizards are found throughout the Mediterranean Basin, and they typically inhabit even the smallest of islets with vegetation. The comparatively low population size, geographic isolation and associated loss of genetic diversity on such islets should limit population persistence, yet it remains poorly understood to what extent insular populations actually suffer from genetic erosion, and to what extent loss of genetic variation and population genetic differentiation are mirrored in the microbiome.
Many species of wall lizards have a distribution that includes a larger, ‘mainland’ island and surrounding islets that differ in size, and sometimes also in vegetation cover and ecological communities. This makes it possible to infer to what extent similar historical and ecological settings – where each species represents one independent ‘natural experiment’ – result in similar population genomic and metagenomics patterns of diversity and differentiation. We aim to establish the signatures of islet life by generating genomic and gut metagenomic data for ‘mainland island’ and islet populations across six Podarcis species.