PNAS:中科院版纳植物园星耀武研究组等揭示横断山植物多样性形
近日，国际著名学术期刊《美国国家科学院院刊》杂志在线发表了中国科学院版纳植物园生物地理与生态学研究组星耀武研究员与芝加哥菲尔德自然历史博物馆的Richard Ree博士合作的一篇研究论文，研究揭示了横断山植物多样性形成机制。
横断山位于青藏高原的东南缘，因其拥有丰富的物种多样性、极端复杂的地形和环境类型而闻名，是全球生物多样性热点之一。该地区的生物多样性形成机制长期以来广受关注，国内乃至国际科技工作者为此进行了大量的探索。为什么横断山孕育了如此丰富的生物多样性?一个流行的假说是随着青藏高原及周边地区在新生代的隆升，导致生境的破碎化和多样性，从而促进了该地区物种的快速分化，但是该假说从未被定量地验证过。
研究利用已发表的分子序列，重建了19个植物类群的系统发育关系和生物地理历史，分析了各个类群的进化速率。不同于大多数以往研究，该项研究根据地质历史将横断山与相邻的青藏高原-喜马拉雅地区相区分，通过对比两个区域的多样性演化历史，探讨了横断山丰富植物多样性的形成机制。研究结果表明，大约在8百万年前，横断山地区的物种分化速率有明显的提高，超过了物种迁移对生物多样性的贡献，横断山地区的物种分化速率与其快速隆升的时间相吻合，并远超隆升更早的青藏高原和喜马拉雅地区;相反地，青藏高原和喜马拉地区的物种分化速率保持稳定，物种多样性的积累以物种迁移为主，尤其在第四纪，从横断山向周边高原和山地的物种迁移有显著提高。该项研究首次从定量的角度比较了物种分化和迁移对特定区域内生物多样性形成的贡献，也支持了横断山在晚中新世的快速隆升促进了生物多样性形成的观点。
原文链接：
Uplift-driven diversification in the Hengduan Mountains, a temperate biodiversity hotspot
原文摘要：
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.
作者：星耀武
