A preliminary study of molecular phylogeny and biogeography distribution pattern of Zelk-ova inferred from trnL-trnF and nrITS sequences

Abstract

Aims Zelkova, belongs to the Ulmaceae, consists of only six species and has a disjunct distribution in East Asia, West Asia and South Europe. Molecular phylogenetic analysis and dispersal and vicariance analysis (DIVA) were employed to analyze phylogenetic relationships and biogeographic pattern of Zelkova. Methods The phylogenetic tree was reconstructed based on DNA sequences of trnL-trnF and ITS regions. The analysis of DIVA was used to deduce the biogeographic pattern. Important findings Results showed that three phylogenetic clades exist in Zelkova, and they correspond to groups from East Asia, West Asia and South Europe. The present phylogenetic tree is different from that in previous study based on nrITS region. 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. The current distribution pattern of this genus was likely shaped by historical geological and environmental events, such as the retreat of Tethys, the Qinghai-Xizang Plateau uplift and the Quaternary glaciations that shrank distribution areas.