Phylogeny of the Stipa and implications for grassland evolution in China: based on biogeographic evidence

Abstract. The evolution of Chinese grassland is a still an important question biogeography. In this study, the phylogeny of 20 Stipa species (extensively distributed in Chinese grassland) was established to explore the origin and dispersal routes of Chinese grassland. It showed that Stipa species originated at 28 MaBP and they started to differentiate in central Inner Mongolia at 22 MaBP. Then, Stipa species expanded along four routes: (1) they expanded from central Mongolia to the Qilian Mountains, Qinghai, and western Tibet at 16 MaBP. They then gradually expanded from western to eastern Tibet from 11–6 MaBP. (2) At 12 MaBP, they expanded from central Inner Mongolia to the Helan Mountains. (3) At 8 MaBP, they expanded from central Inner Mongolia to the Xinjiang area. (4) At 4 MaBP, they expanded from central to eastern Inner Mongolia. Therefore, we could deduce the formation order of Chinese grasslands: central Inner Mongolia > Qilian Mountains > Qinghai > western Tibet > Helan Mountains > Xinjiang > central Tibet > eastern Tibet > eastern Inner Mongolia. We highlight the importance of the uplift of the Qinghai-Tibet Plateau and paleoclimate changes in triggering the origin and evolution of Stipa species and Chinese grasslands.