Cytogeographic patterns of angiosperms flora of the Qinghai-Tibet Plateau and Hengduan Mountains

Abstract

The Qinghai-Tibet Plateau and Hengduan Mountains is an important hotspot to study the origin and evolution of plant biodiversity, which is characterized by high species richness and endemism, as well as a unique location and complicated topography. Based on a comprehensive survey of the chromosome numbers of angiosperms from the Qinghai-Tibet Plateau and Hengduan Mountains, our results indicated that the frequency of neopolyploids (23%) was much lower than expected. This was likely caused by the unique history, geology, and complicated topography and habitat. Another mechanism of chromosomal evolution is on the diploidy level (ca. 43.3%), with variations of chromosomal restructure and karyotype. The number of paleopolyploids (diploids with high base numbers) was large in plants from this mountain area (33.7%). The diversity of chromosomal evolution patterns of angiosperms from this region may be correlated to the high level of species richness and endemism. This study provides useful insight into our understanding of speciation, the origins of alpine flora and other important issues in eastern Asia and other regions in the Northern Hemisphere.