The Species Differentiation And Phylogeography Of Smilax Sect. Nemexia In East Asia

There are 11 species in Smilax Sect, nemexia. They are disjuct in East Asia (EA) and North-America(NA). There are two species in Eastern Asia, Smilax riaparia and S. nipponica, while other nine in North-America. They are S. ecirrhata, S. herbacea, S. biltmoreana, S. hugeri, S. illinoensis, S. lasioneuron, S. pseudo-china, S. pulverulenta and S. jamesii. The two Asian herb Smilax are widely distributed in the Mid-Western China, Eastern China, Northern China, and also in Japan and Korea. To investigate the phylogeography and phylogeny of the two Asian species, we choose 60 populations (416 individuals) using two cpDNA fragements in this research, including 17 populations of North America as contrast. The results are as follows:(1) The combined sequence of rbcL/atpB and atpl/atpH have detected 64 polymorphic sites and generated 65 haplotypes. The haplotype diversity (h) and the nucleotide diversity (Pi) in S. riparia are 0.937 and 0.00739, respectively, which is higher than that of S. nipponica'(Pi= 0.00279, h=0.712). AMOVA analysis revealed that most of the existing variation are mainly among populations, in S. riparia, Fst=0.68985 and in S. nipponia, Fst=0.92952.(2) The haplotype diversity and the haplotype distributing map shows that there are two diversification centers and refuges in East Asia, one is the region of the Mid-Western China, including Mt.Tianping in Hunan province(TPS), and Dalaoling(DLL), Mt.Shennong(SNJ), Xianfeng (XF) in Hubei province; Another is in Eastern China,that is Yixing (YX) in Jiangsu province, Tiantangzhai (TTZ) in Anhui province and Mt. Tianmu (TMS) in Zhejiang province.(3) The current pattern of herb Smilax in Asia came from the event of migrating eastward and northward from the west. It is also discovered that the herb Smilax in Taiwan, China, Japan and Korea has a close relationship with the mainland, which may be the original place.(4) BEAST analysis shows that the divergence time of two species'is about 16.2 mya, the divergence time between populations in S. riparia is around 15.2 mya, while the S. nipponica populations differentiated 8.5 mya.(5) The phylogenetic tree based on cpDNA indicates that there is no haplotype shared between S. riparia and S. nipponica, the differentiation of the two species is apparent.This research also surports the existence of var. acuminate in South-western China.