Qi, Zhechen , Li, Pan , Zhao, Yunpeng , Cameron, Kenneth , Fu, Chengxin .
Molecular phylogeny and biogeography of Smilacaceae (Liliales), a cosmopolitan family of monocots.
Smilacaceae (Liliales), generally recognized to include at least two genera, Smilax and Heterosmilax, are a group of climbing monocots with worldwide distribution, containing over 200 species with alternate leaves characterized by reticulate venation, a pair of petiolar tendrils and usually prickly stems. We collected molecular evidence from nDNA (At103), rDNA (ITS) and cpDNA (matK, ndhA, ndhF, rpl16 intron) from 135 taxa, resulting in a matrix with total alignment length >8000 bp. Our taxon sampling covered all sections of Smilax from all major distribution zones of the family; species from Ripogonaceae and Philesiaceae were chosen as outgroups. A phylogenetic tree was constructed, and this provides a robust framework within which to consider the possible evolutionary history of this family. Heterosmilax was found to be a subclade within Smilax, confirming its sectional status. Distribution of major clades within Smilacaceae showed a conspicuous geographical pattern, with a split between the Old World and New World, except for Smilax apera L., which is sister to the rest of the family members and distributed on three continents. Inter-continental migration and long distance dispersal events were detected in both Old and New World clades. Bayesian MCMC DIVA analysis was conducted to reconstruct the ancestral distribution of Smilacaceae. The results show a probable South American origin of Smilacaceae. We applied a relaxed molecular clock method to infer the divergence times of all extant lineages of Smilacaceae, calibrating the phylogenetic tree with the oldest Ripogonum fossil record and an estimated age of the Smilacaceae stem node. Our analysis suggests that divergence within Smilacacecae started in the late Eocene (40 mya). Three lineages: the Smilax aspera clade, Old World clade, and New World clade, evolved at the transition time between the Eocene and Oligocene. Sectional-level divergence within Smilacaceae was estimated to have occurred in the middle Miocene. A rapid speciation and radiation event was found at the Miocene/Pliocene boundary. The rise of the Himalayas, and a more complex geography in eastern Asia might be responsible for the greater species richness of Smilacaceae in Asia than in North America. Ancestors of African and Australian species such as S. kraussiana and S. australis probably dispersed from South or Southeast Asia.
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1 - Harvard University, Organismic Evolution and Biology, 22 Divinity Ave, OEB, Davis lab, Cambridge, MA, 02138, USA
2 - University Of Wisconsin, Madison, Botany, 430 Lincoln Dr, Madison, WI, 53706, USA
3 - Zhejiang University, College Of Life Sciences, 388 Yuhangtang Rd., Hangzhou, Zhejiang, N/A, 310058, China
4 - University Of Wisconsin, Department Of Botany, 154 Birge Hall, 450 Lincoln Drive, Madison, WI, 53706, USA
5 - Lab Of Syst. & Evol. Botany And Biodiversity, Zijinhua Road 368,, Hangzhou, 310029, China
Presentation Type: Oral Paper:Papers for Sections
Location: Delaware B/Hyatt
Date: Tuesday, July 10th, 2012
Time: 2:00 PM