Xiao Yuanming, Yang Lucun, Nie Xiuqing, Li Changbin, Xiong Feng, Wang Lingling, Zhou Guoying
Northwest Institute of Plateau Biology Chinese Academy of Sciences Xining China.
University of Chinese Academy of Sciences Beijing China.
Ecol Evol. 2020 Jun 8;10(13):6723-6731. doi: 10.1002/ece3.6402. eCollection 2020 Jul.
Periodic climatic oscillations and species dispersal during the postglacial period are two important causes of plant assemblage and distribution on the Qinghai-Tibet Plateau (QTP). To improve our understanding of the bio-geological histories of shrub communities on the QTP, we tested two hypotheses. First, the intensity of climatic oscillations played a filtering role during community structuring. Second, species dispersal during the postglacial period contributed to the recovery of species and phylogenetic diversity and the emergence of phylogenetic overdispersion. To test these hypotheses, we investigated and compared the shrub communities in the alpine and desert habitats of the northeastern QTP. Notably, we observed higher levels of species and phylogenetic diversity in the alpine habitat than in the desert habitat, leading to phylogenetic overdispersion in the alpine shrub communities versus phylogenetic clustering in the desert shrub communities. This phylogenetic overdispersion increased with greater climate anomalies. These results suggest that (a) although climate anomalies strongly affect shrub communities, these phenomena do not act as a filter for shrub community structuring, and (b) species dispersal increases phylogenetic diversity and overdispersion in a community. Moreover, our investigation of the phylogenetic community composition revealed a larger number of plant clades in the alpine shrub communities than in the desert shrub communities, which provided insights into plant clade-level differences in the phylogenetic structures of alpine and desert shrub communities in the northeastern QTP.
冰期后时期的周期性气候振荡和物种扩散是青藏高原植物群落及其分布的两个重要成因。为了加深我们对青藏高原灌木群落生物地质历史的理解，我们检验了两个假设。其一，气候振荡强度在群落构建过程中起到了筛选作用。其二，冰期后时期的物种扩散促进了物种和系统发育多样性的恢复以及系统发育过分散的出现。为了验证这些假设，我们对青藏高原东北部高山和荒漠栖息地的灌木群落进行了调查和比较。值得注意的是，我们观察到高山栖息地的物种和系统发育多样性水平高于荒漠栖息地，导致高山灌木群落出现系统发育过分散，而荒漠灌木群落则出现系统发育聚类。这种系统发育过分散随着气候异常加剧而增加。这些结果表明：（a）尽管气候异常对灌木群落有强烈影响，但这些现象并非灌木群落构建的筛选因素；（b）物种扩散增加了群落中的系统发育多样性和过分散。此外，我们对系统发育群落组成的调查显示，高山灌木群落中的植物分支数量多于荒漠灌木群落，这为了解青藏高原东北部高山和荒漠灌木群落系统发育结构在植物分支水平上的差异提供了见解。
