Rapid radiation and dispersal out of the Qinghai-Tibetan Plateau of an alpine plant lineage Rhodiola (Crassulaceae).
Rhodiola L. (Crassulaceae) is a mid-sized plant genus consisting of about 70 species, with most species distributed on the Qinghai-Tibetan Plateau (QTP) and the adjacent areas, and several species in north-east Asia, Europe, and North America. This study explored the origin and diversification history of Rhodiola and tested the biogeographic relationships between the QTP and other regions of the Northern Hemisphere. We sequenced the nuclear ribosomal internal transcribed spacers and eight plastid DNA fragments representing 55 species of Rhodiola, and reconstructed phylogenetic relationships with maximum parsimony, maximum likelihood and Bayesian inference. Several instances of incongruence between the nuclear and the plastid data sets were revealed, which can best be explained by reticulate evolution. Species of Rhodiola and Pseudosedum form a well-supported clade sister to Phedimus. Dating analysis suggested that the origin and diversification times of this group are largely correlated with the extensive uplifts of the Qinghai-Tibetan Plateau. Ancestral state reconstruction supports the hypothesis that Rhodiola originated on the QTP, and then dispersed to other regions of the Northern Hemisphere. Our findings highlight the importance of the uplifts of the Qinghai-Tibetan Plateau in promoting species diversification and the possible role of reticulate evolution in the diversification process. Our results also suggest the biogeographic significance of QTP as the source area in alpine plant evolution in the Northern Hemisphere.
College of Life Sciences, Peking University, Beijing 100871, China.
Jian-Qiang
JQ
Zhang
College of Life Sciences, Peking University, Beijing 100871, China.
Shi-Yong
SY
Meng
Department of Biology, University of Victoria, PO Box 3020 STN CSC, Victoria, BC V8W 3N5, Canada.
Geraldine A
GA
Allen
Department of Botany, National Museum of Natural History, MRC 166, Smithsonian Institution, Washington, D.C. 20013-7012, USA. Electronic address: wenj@si.edu.
Jun
J
Wen
College of Life Sciences, Peking University, Beijing 100871, China. Electronic address: rao@pku.edu.cn.
Guang-Yuan
GY
Rao
D001499:Bayes Theorem; D002681:China; D010802:Phylogeny; D018087:Plastids / Q000235:genetics; D029771:Rhodiola / Q000235:genetics*; D012270:Ribosomes / Q000235:genetics; D017422:Sequence Analysis, DNA
Ancestral distribution; Divergence time; Qinghai-Tibetan Plateau; Rapid radiation; Reticulate evolution; Rhodiola