1. Key Laboratory of Adaption and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, Qinghai, P. R. China
2. Key Laboratory of Adaption and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, Qinghai, P. R. China, University of Chinese Academy of Sciences, Beijing 100039, P. R. China
3. Department of Biology, University of Leicester, Leicester LE1 7RH, U.K.
4. Key Laboratory of Plant Resources and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, Guangdong, P. R. China
5. Key Laboratory of Adaption and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, Qinghai, P. R. China;, Email: slchen@nwipb.cas.cn