A Preliminary Study Of Molecular Phylo-geny And Biogeography Of Zelkova Spach (Ulmaceae) Inferred From CpDNA TrnL-F And NrITS Regions

Zelkova Spach, belongs to Ulmaceae and consists of only six species, has a disjunct distribution in East Asia, West Asia and South Europe. The recent molecular research of Zelkova only using the ITS sequences, and the results are not exactly matching with the classification results, also been not quite the same with the geographical distribution, then a more in-depth molecular systemsthe study is extremely necessary.A matrix that includes18species (11from Zelkova and7from related genera), two molecular markers (nrDNA ITS, cpDNA trnL-trnF) was created. This matrix was analyzed using maximum parsimony (MP), maximum likelihood (ML), and Bayesian Inference (BI) methods to study phylogenetic relationships within Zelkova and related genera. The dispersal and vicariance analysis (DIVA) were employed to analyze biogeographic pattern of Zelkova. The main results are as summarized as follows:(1) Phylogenetic tree was reconstructed based on DNA sequences of trnL-F and ITS regions. The analysis of DIVA was used to deduce the biogeographic inference. Results showed that three phylogenetic clades exist in Zelkova, which correspond to groups of East Asia, West Asia and South Europe respectively. The present phylogenetic tree is different from that in previous study based on nrITS region, while it matches the classification results and the geographical distribution. We considered this result is more completely and correctly.(2) DIVA analyses of this genus indicated that the ancestral area of Zelkova was a larger area including East Asia, West Asia and South Europe. The speciation process was dominant by vicariance. Each of the three areas was gradually separated from vicariant events. Based on the high level of species diversity of Zelkova in East Asia, the center of origin is probably the northern Pacific, i.e. north of China and Japan. Current distribution pattern of this genus was likely shaped by the historical geological and environmental events, such as the retreat of Tethys, the Qinghai-Tibetan Plateau uplift and the Quaternary glaciations, which shrank distribution areas. Molecular phylogenetic analysis and dispersal and vicariance analysis (DIVA) were employed to analyze phylogenetic relationships and biogeographic pattern of Zelkova.