Caretta caretta Mediterranean population genomics

Sea turtles are predicted to be heavily impacted by climate change, causing feminisation of the populations and the decline in hatchling survival rates. Here, we combined genomic information of Mediterranean loggerhead sea turtle nesting populations with environmental, behavioural and reproductive data to investigate their population structure and understand mechanisms of adaptation. We found substantial genetic differentiation among almost all rookeries, with a major break between Greek locations, followed by Libya and the remaining populations. This genetic structuring, caused by male and female philopatry, was also shaped by a local adaptation with strong signals of all the phenotypic and environmental variables tested. A conservation prioritisation analysis identified the areas with higher priority for protection, concluding that protecting all rookeries is essential to retain the genetic diversity and adaptive potential of the Mediterranean region while maintaining connectivity. Our study provides the baseline for future studies on sea turtle genomics for conservation.