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

摘要

We sequenced partial mitochondrial DNA from the cytochrome b gene (1143bps) 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 (0.01Ma) 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.

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