Xing Yaowu, Ree Richard H
Life Sciences Section, Integrative Research Center, The Field Museum, Chicago, IL 60605.
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yunnan 666303, China.
Proc Natl Acad Sci U S A. 2017 Apr 25;114(17):E3444-E3451. doi: 10.1073/pnas.1616063114. Epub 2017 Apr 3.
A common hypothesis for the rich biodiversity found in mountains is uplift-driven diversification-that orogeny creates conditions favoring rapid in situ speciation of resident lineages. We tested this hypothesis in the context of the Qinghai-Tibetan Plateau (QTP) and adjoining mountain ranges, using the phylogenetic and geographic histories of multiple groups of plants to infer the tempo (rate) and mode (colonization versus in situ diversification) of biotic assembly through time and across regions. We focused on the Hengduan Mountains region, which in comparison with the QTP and Himalayas was uplifted more recently (since the late Miocene) and is smaller in area and richer in species. Time-calibrated phylogenetic analyses show that about 8 million y ago the rate of in situ diversification increased in the Hengduan Mountains, significantly exceeding that in the geologically older QTP and Himalayas. By contrast, in the QTP and Himalayas during the same period the rate of in situ diversification remained relatively flat, with colonization dominating lineage accumulation. The Hengduan Mountains flora was thus assembled disproportionately by recent in situ diversification, temporally congruent with independent estimates of orogeny. This study shows quantitative evidence for uplift-driven diversification in this region, and more generally, tests the hypothesis by comparing the rate and mode of biotic assembly jointly across time and space. It thus complements the more prevalent method of examining endemic radiations individually and could be used as a template to augment such studies in other biodiversity hotspots.
关于山区丰富生物多样性的一个常见假说是隆升驱动的多样化，即造山运动创造了有利于本地居群快速原地物种形成的条件。我们在青藏高原（QTP）及毗邻山脉的背景下检验了这一假说，利用多组植物的系统发育和地理历史来推断生物群落随时间和跨区域的组装节奏（速率）和模式（定殖与原地多样化）。我们聚焦于横断山脉地区，与青藏高原和喜马拉雅山脉相比，该地区隆升时间较晚（自中新世晚期以来），面积较小但物种更为丰富。时间校准的系统发育分析表明，约800万年前，横断山脉原地多样化速率增加，显著超过地质历史更悠久的青藏高原和喜马拉雅山脉。相比之下，同期青藏高原和喜马拉雅山脉原地多样化速率相对平稳，定殖主导了谱系积累。因此，横断山脉植物区系的形成在很大程度上是近期原地多样化的结果，在时间上与造山运动的独立估计相一致。这项研究为该地区隆升驱动的多样化提供了定量证据，更广泛地说，通过跨时间和空间联合比较生物群落组装的速率和模式来检验这一假说。因此，它补充了更普遍的单独研究特有辐射的方法，并可作为模板用于加强其他生物多样性热点地区的此类研究。
