Original Research ARTICLE
A PHYTOGEOGRAPHIC DIVIDE ALONG THE 500 MM ISOHYET IN THE QINGHAI-TIBET PLATEAU：INSIGHTS FROM THE PHYLOGEOGRAPHIC EVIDENCE OF CHINESE ALLIUMS (AMARYLLIDACEAE)
- 1Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, Sichuan University, China
The Qinghai-Tibet Plateau (QTP) has been biogeographically divided into the eastern monsoonal and the western continental climatic zones along the 500 mm isohyet. However, this biogeographic hypothesis has been rarely tested using a phylogeographic approach. The members of the genus Allium subgenus Cyathophora coincidentally distribute across this biogeographical divide. Intriguingly, Allium fasciculatum of subgenus Amerallium co-occurs in the distribution range of subgenus Cyathophora. To illuminate the role of this biogeographic divide on the genetic divergence, we genotyped 466 individuals of 52 populations of subgenus Cyathophora and 110 individuals of 19 populations of A. fasciculatum using three chloroplast DNA fragments, whole nrITS and 9 nuclear microsatellite loci, supplemented with the present environmental space and paleo-distribution modeling. Our phylogeographical evidence recovered the concordant east-west genetic breaks both for subgenus Cyathophora and A. fasciculatum along the 500 mm isohyet. The divergence time estimations and environmental niche differentiations suggested this east-west genetic breaks could have been triggered by the climatic-induced vicariance during the early Pleistocene. Noticeably, this split within subgenus Cyathophora could have been deepened by the morphological vicariance from the eastern umbel to the western spicate, while that within A. fasciculatum could have been obscured due to the pollen flows from the east to west caused by the postglacial expansion. The genetic structures and ENMs recovered the distinct responses to the Quaternary climatic oscillations for species constricted to different climatic zones, further highlighting the profound effect of the climatic differences and tectonic uplifts on the genetic diversification. Overall, our findings offer strong evidence for the existence of a biogeographic divide between the eastern monsoonal and the west continental climatic zones of the QTP nearly along the 500 mm isohyet.
Keywords: Allium, Pleistocene, phytogeographic divide, genetic breaks, Qinghai-Tibet Plateau
Received: 24 Jul 2018;
Accepted: 28 Jan 2019.
Edited by:Genlou Sun, Saint Mary's University, Canada
Reviewed by:Yessica Rico, Instituto de Ecología (INECOL), Mexico
Ferhat Celep, Kırıkkale University, Turkey
Copyright: © 2019 Li, Xie, Xie, Deng, Zhong, Yu and He. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Prof. XingJin He, Key Laboratory of Bio-resource and Eco-environment of Ministry of Education, Sichuan University, Chengdu, Sichuan Province, China, firstname.lastname@example.org