Late Quaternary microevolution of endemic Mediterranean island reptiles in response to environmental and anthropogenic change

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Oceanic islands have long attracted the attention of evolutionary biologists, as they constitute natural laboratories allowing for the detailed study of evolutionary processes in a spatially confined terrestrial environment. Reptiles are famous model systems for island studies, but there is a strong mismatch between the number of investigations on extant island reptiles, which are common, and that on fossil representatives. This is unfortunate because fossil island reptile communities represent excellent systems for studying evolutionary change through time, as well as eco-evolutionary interactions in light of changing environments. In the present application, focus will be on the island herpetofauna of the Mediterranean Balearic Islands, specifically on the endemic wall lizard of Ibiza, Podarcis pityusensis, using both the exceptional Late Quaternary fossil record at the cave site Es Pouàs and investigations on modern populations to address questions on morphological and ecological evolution through time relative to the glacial/interglacial transition, human arrival, and associated changes in environment and vertebrate communities. a) Using isotopes and morphological studies on the dentition of fossil and extant individuals and populations we will test if P. pityusensis shifted its relative position within the Ibiza vertebrate community in response to biotic and abiotic change; b) using micro-computed tomography and 3D geometric morphometrics we will test if P. pityusensis reacted to environmental perturbation induced by glacial/interglacial climatic transitions, anthropogenic factors, and changes in community composition by shifting its range of phenotypic expressions, e.g. in terms of fluctuating asymmetry, size, and overall body proportions. The expected results will, largely for the first time, reveal detailed temporal information about phenotypic and ecological responses of an island reptile to environmental change and anthropogenic alterations over several tens of thousands of years, which will not only be interesting from a paleontological point of view but also have the potential to provide valuable information for conservation efforts on the extant populations of P. pityusensis. A highly beneficial side effect of the study will be the reconstruction of the isotopic community composition of the Ibiza vertebrates through time.