The compound group of Adiantum palmatum is a monophyletic group

The East Asia North America discontinuity is the most classical biogeographic model in the temperate component discontinuity of plants in the northern hemisphere, but there is still no case study of this distribution pattern in pteridophytes There are four species in the complex of Adiantum aleuticum, a pedatum, a aleuticum and a viridimontanum, and a pedatum and a myriosorum in East Asia (Fig 1) Recently, a research team composed of Dr Lu Jinmei, researcher Li Debao and Professor Wen Jun of Smithsonian Institution of Kunming Institute of Botany, Chinese Academy of Sciences, has carried out in-depth systematic and biogeographic studies on the complex of Adiantum palmatum In this study, five chloroplast fragments (atpA, ATPB, rbcL, trnL-F, and RPS4 trns) from 100 samples were sequenced and the phylogenetic relationships within the complex were reconstructed The results show that the complex group of Adiantum palmatum is a monophyletic group, and its sister group is a edentulum distributed in East Asia (Fig 2) A pedatum did not gather into one branch, but into three sub branches A The branches composed of aleuticum and a viridimontanum are converged into a pedatum Myriosorum is a sister group of A pedatum-a aleuticum Diva and Lagrange analysis showed that the complex group originated from East Asia, and its crown differentiation time was about 4.27 (2.24-6.57) million years ago The results show that the currently recognized a pedatum may need to be divided into at least three species (corresponding to the populations of eastern North America, China and Japan respectively) The East Asia North America discontinuity pattern in the Adiantum palmatum complex may be formed by two intercontinental migrations, one from East Asia to North America in the late Tertiary and the other from North America to East Asia in the Pleistocene This study is the first attempt to compare and study the similarities and differences between ferns and seed plants in East Asia North America discontinuous distribution pattern The results are of great significance to the study of the intercontinental discontinuous distribution pattern and transmission route of pteridophytes The research paper is entitled "biological separation between eastern Asia and North America in the Adiantum pedatum complex (Pteridaceae)", which is published in the international famous journal of Botany (top 15% Journal of JCR in botany in 2011) The project is supported by 973 Project (2007cb411601), National Natural Science Foundation Project (31070199), knowledge innovation project of Chinese Academy of Sciences (2010kiba02) and large scientific device open research project of Chinese Academy of Sciences (2009-lsf-gbows-01).