Mitochondrial DNA phylogeography reveals a west–east division of the northern grass lizard (Takydromus septentrionalis) endemic to China

We sequenced partial mitochondrial DNA from the cytochrome b gene (1143 bps) for 385 northern grass lizards (Takydromus septentrionalis) from 14 mainland and 14 island populations covering almost the lizard’s entire range to examine the influence of geographic barriers (mountain ranges and water bodies) on the diversification of lineages. Phylogenetic analyses revealed a detailed distribution of three evolutionary lineages (W, E and G). Lineage G included individuals exclusively from Guiyang, in the south‐western distributional limit. Lineage W included individuals from the central and western parts of the lizard’s range on the mainland. Lineage E included individuals from East China, both on the mainland and on islands in the East China Sea. Haplotypes from lineages W and E were co‐distributed in Chuzhou and Chibi. The averaged pairwise distance of 6.23% between these lineages indicated a Miocene‐Pliocene lineage‐split. Lineage E was further subdivided to three sublineages: E1 and E2 comprised of haplotypes from the Zhoushan Islands, and E3 included haplotypes from the eastern mainland, the Zhoushan Islands and two islands south of the Zhoushan Islands. Lineages W and E showed evidence of demographic extensions. The isolation caused by the last transgression (0.01 Ma) has not yet led to a significant genetic differentiation between mainland and island populations in East China. However, divergence among some small islands may be driven by the restriction of migration and genetic drift.