EAPSI: Investigating Historical Changes in Montane River Systems and Their Roles in Species Diversification

Wang Kai, La Jolla CA

Investigators

Abstract

Ancient geological events such as changes in river drainages and the formation of mountain ranges can have profound impacts on the genetic structure and evolution of organisms. By analyzing the genetic diversity of different populations of organisms across complex environments, inferences can be made about the timing and distribution of such historical processes and their impacts on species evolution. The Hengduan Mountain Region (HMR) is positioned at the transition zone between the Tibetan Plateau and lowland southwest China. This region is unique in having repeated, parallel, montane river systems that run across dramatic elevational and environmental gradients. Studies have shown that the major rivers of the region (Mekong, Salween, and Yangtze) have experienced significant changes in drainage patterns and flow directions in the past due to the continental collisions between Eurasia and India and the subsequent formation of the Tibetan Plateau, and these geological events have impacted genetic structures among some aquatic animals and plants in the region. However, the timing and geographic scope of changes in river topology remain poorly understood, and nothing is known to date about the impact of such events on the evolution of terrestrial vertebrates. Lizard species of the genus Japalura are recognized to be associated closely with habitats along river systems in the HMR. With many species endemic to the HMR, the group of terrestrial lizards is well suited for investigating the impact of historical geologic- and environmental-changes on population and species diversification in the region. In collaboration with Dr. Jing Che from the Chinese Academy of Sciences, this research will employ modern molecular techniques to the genetic data of endemic lizards in the HMR. Through field-based surveys of species diversity of lizards and lab-based studies of genetic diversity of the focal species group across the HMR, this research not only will promote biodiversity and conservation studies of the focal species group in a fragile ecosystem, but also, it will further our knowledge of the historical importance of the formation of the Tibetan Plateau for changes in river systems as well as for vertebrate diversification in the HMR. During the research period in China, fieldwork will be conducted in targeted valley habitats along the three major rivers (Mekong, Salween, and Yangtze) in the Hengduan Mountain Region (HMR) of China to increase available taxonomic and geographic sampling of focal lizard species in the genus Japalura. Combined with samples available already at the host institution in China, genomic DNA will be extracted from tissue samples, and target genes (mitochondrial and nuclear) will be amplified and sequenced at the host institute in China. Phylogenetic approaches will be employed to study population genetic and biogeographic patterns, and estimate the timing of lineage divergence, among focal lizard species across the HMR. The results will be used to formulate biogeographical hypotheses concerning the role that historical changes in river system and formation of mountain ranges played in the vertebrate diversification around the Tibetan Plateau. The award, under the East Asia and Pacific Summer Institutes program, supports summer research by a U.S. graduate student and is jointly funded by NSF and the Chinese Ministry of Science and Technology.