1Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, the Chinese Academy of Sciences, Xining 810001, China 2MOE Key Laboratory of Arid and Grassland Ecology, Lanzhou University, Lanzhou 730000, China 3Laboratory of Pollination Ecology, Institute of Evolution, Faculty of Science and Science Education, Haifa University, Haifa 31905, Israel
About author:†Present address: Institute of Tibetan Plateau Research at Kunming, Kunming Institute of Botany, the Chinese Academy of Sciences, Kunming 650204, China **Author for correspondence Tel: +86 931 8914 305; Fax: +86 931 8914 288 E-mail: ljqdxy@public.xn.qh.cn; liujq@nwipb.ac.cn