A joint team of researchers led by Prof. ZHANG Yaping from Kunming Institute of Zoology of Chinese Academy of Sciences has discovered evidence that historical drainage patterns adjacent to the Qinghai-Tibetan Plateau differed markedly from those of today.

The researchers examined the relationship between drainage history and geographic patterns of genetic variation in the Yunnan spiny frog, Nanorana yunnanensis, using approximately 981 base pairs of mitochondrial DNA partial sequences from protein-coding genes ND1 and ND2, and intervening areas including complete tRNAIle, tRNAGln and tRNAMet.

They identified three major well-supported maternal lineages, each of which had two sublineages. It is found that these divergent lineages were completely concordant with six geographical regions. Genetic structure and divergence were strongly congruent with historical rather than contemporary drainage patterns.

“Most lineages and sublineages were formed via population fragmentation during the rearrangement of paleodrainage basins in the Early Pliocene and Early Pleistocene. Extensive population expansion probably occurred early in the Middle Pleistocene accompanying dramatic climatic oscillations”, said Prof. ZHANG.

The research is reported in the (2010)19 issue of the journal Molecular Ecology under the title of “Genealogy and palaeodrainage basins in Yunnan Province: phylogeography of the Yunnan spiny frog, Nanorana yunnanensis (Dicroglossidae)”.