2.1. Sampling and DNA extractions
Tails tissues of 100 specimens of Podarcis lilfordi were collected between 2015 and 2016 from eight islets in the Menorca and Mallorca archipelagos (Balearic Islands) (10-22 samples per islet) (Figure 1 and Table 1). Islets encompassed a representative subsample of the current species geographic distribution and vary in several geographic and ecological aspects, including surface area, maximum altitude, vegetation cover and type, presence of human settlements and other vertebrates, as well as lizard demographic traits (Mayol et al., 2020; Pérez-Mellado et al., 2008; Rotger et al., 2021). Specimens were captured using pitfall traps placed along paths and vegetation edges, sexed according to visual examination and morphology (Rotger et al., 2016), weighted, and body size measured as snout to vent length (SVL) (see Table S1 for specimen information). Tails were preserved in 100% ethanol and kept at -80°C until processed. Permits for sampling were provided by Conselleria d’Agricultura i Medi Ambient i Territori, Govern de les Illes Balears (CEP 31/2015 to LB and CEP 6/14 to GT). Genomic DNA was extracted with DNAeasy Tissue and Blood kit (Qiagen) with RNase treatment. DNA concentration was measured with Qubit 2 fluorometer (Invitrogen, Waltham). About 1 ug of genomic DNA per sample was sent toCentro Nacional de Analisis Genomico (CNAG, Spain) for sequencing. DNA integrity and concentration was further measured on a fragment analyzer (Agilent Bioanalyzer) and high-quality samples with at least 10 ng/µl were selected for sequencing.