Evolution and biogeography of the slipper orchids: eocene vicariance of the conduplicate genera in the old and new world tropics
作者：Yan-Yan Guo, Yi-Bo Luo, Zhong-Jian Liu, Xiao-Quan Wang*
影响因子：4.537
刊物名称：PLoS One
出版年份：2012
卷：7 期：6 页码：e38788
文章摘要：
Intercontinental disjunctions between tropical regions, which harbor two-thirds of the flowering plants, have drawn great
interest from biologists and biogeographers. Most previous studies on these distribution patterns focused on woody plants,
and paid little attention to herbs. The Orchidaceae is one of the largest families of angiosperms, with a herbaceous habit
and a high species diversity in the Tropics. Here we investigate the evolutionary and biogeographical history of the slipper
orchids, which represents a monophyletic subfamily (Cypripedioideae) of the orchid family and comprises five genera that
are disjunctly distributed in tropical to temperate regions. A relatively well-resolved and highly supported phylogeny of
slipper orchids was reconstructed based on sequence analyses of six maternally inherited chloroplast and two low-copy
nuclear genes (LFY and ACO). We found that the genus Cypripedium with a wide distribution in the northern temperate and
subtropical zones diverged first, followed by Selenipedium endemic to South America, and finally conduplicate-leaved
genera in the Tropics. Mexipedium and Phragmipedium from the neotropics are most closely related, and form a clade sister
to Paphiopedilum from tropical Asia. According to molecular clock estimates, the genus Selenipedium originated in
Palaeocene, while the most recent common ancestor of conduplicate-leaved slipper orchids could be dated back to the
Eocene. Ancestral area reconstruction indicates that vicariance is responsible for the disjunct distribution of conduplicate
slipper orchids in palaeotropical and neotropical regions. Our study sheds some light on mechanisms underlying generic
and species diversification in the orchid family and tropical disjunctions of herbaceous plant groups. In addition, we suggest
that the biogeographical study should sample both regional endemics and their widespread relatives.
