For further understanding and elucidating what have triggered the high levels of biodiversity and molecular adaptive evolution, it is essential to investigated phylogenetic relationships and evolutionary patterns of organisms endemic to Qinghai-Tibetan plateau from morphological to molecular level. Applying molecular biology technique, our research teams have conducted nice work on the research fields as follows:
1. Molecular phylogeny and historical structure of fishes endemic to the plateau
We investigated the phylogenetic relationships of the schizothoracine fishes and historical population structure of Schizopygopsis pylzovi based on the complete cytochrome b sequence. The molecular phylogenetic relationships among the schizothoracine fishes, coupled with the morphological analyses revealed that the subfamily Schizothoracinae forms a well-supported monophyletic group having close relationship with species of subfamily Barbinae. The divergence of major clades within the subfamily Schizothoracinae happened during 11.7~10.9Mya and 10.1~9.4 Mya, and the main speciation events occurred largely 6.1~0.4 Mya, suggesting the major cladogenetic events and speciation of the subfamily Schizothoracinae are mostly correlated with the geological tectonic events and intensive climate shift occurred in the course of uplifts of the Qinghai-Tibetan Plateau. These species are endemic to the Qinghai-Tibetan Plateau, a region with a history of geological activity and a rich diversity of habitats that may have resulted in the parallel and reversal evolution of some morphological characters used in their taxonomies. A significant genetic variation was observed among populations within drainage systems and among drainage systems, indicating significant geographical structuring of Schizopygopsis pylzovi. The contemporary population structure and differentiation of Schizopygopsis pylzovi may be consistent with the historical tectonic events occurred in the uplifts of the Qinghai-Tibetan Plateau. The fluctuations of ecogeographical environment and major hydrographic formation might have promoted contiguous range expansion of freshwater fish population, whereas the geological barriers among drainages have resulted in fragmentation of population and restricted gene flow among populations. In addition, the significantly large negative Fs value (-24.91, P<0.01) of Fu’s Fs test and the unimodal mismatch distribution indicate that the species Schizopygopsis pylzovi have undergone a sudden population expansion after the historical tectonic event of Gonghe Movement (0.11Mya).