Climate-driven selection may shape mitochondrial genome evolution in Scincidae

Skinks (family Scincidae) are one of the most widely distributed lizard groups, and hence they are likely subjected to varying selective pressures and metabolic demands. In this study, we assembled 16 complete mitochondrial genomes from skink species. Phylogenetic relationships and divergence times within Scincidae were reconstructed using these data. Subsequently, 36 distinct skink species were classified into five distinct clusters based on bioclimatic variables. Notably, positively selected sites were detected at amino acid position 93 of the ND2 gene in the cluster A (Chalcides ocellatus and C. sepsoides) and at position 267 of the ND1 gene in the cluster 2 (including members of Scincinae and Sphenomorphinae). Environmental correlation analyses revealed that temperature seasonality and precipitation seasonality exhibited the strongest statistical associations with mitochondrial protein-coding genes, particularly COX3 and ND1 genes. These results suggest that the mitochondrial genes of skinks may have been shaped by climate-driven selection.