Hughes Colin, Eastwood Ruth
Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, United Kingdom
Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, United Kingdom.
Proc Natl Acad Sci U S A. 2006 Jul 5;103(27):10334-10339. doi: 10.1073/pnas.0601928103. Epub 2006 Jun 26.
Species radiations provide unique insights into evolutionary processes underlying species diversification and patterns of biodiversity. To compare plant diversification over a similar time period to the recent cichlid fish radiations, which are an order of magnitude faster than documented bird, arthropod, and plant radiations, we focus on the high-altitude flora of the Andes, which is the most species-rich of any tropical mountains. Because of the recent uplift of the northern Andes, the upland environments where much of this rich endemic flora is found have been available for colonization only since the late Pliocene or Pleistocene, 2-4 million years (Myr) ago. Using DNA sequence data we identify a monophyletic group within the genus Lupinus representing 81 species endemic to the Andes. The age of this clade is estimated to be 1.18-1.76 Myr, implying a diversification rate of 2.49-3.72 species per Myr. This exceeds previous estimates for plants, providing the most spectacular example of explosive plant species diversification documented to date. Furthermore, it suggests that the high cichlid diversification rates are not unique. Lack of key innovations associated with the Andean Lupinus clade suggests that diversification was driven by ecological opportunities afforded by the emergence of island-like habitats after Andean uplift. Data from other genera indicate that lupines are one of a set of similarly rapid Andean plant radiations, continental in scale and island-like in stimulus, suggesting that the high-elevation Andean flora provides a system that rivals other groups, including cichlids, for understanding rapid species diversification.
物种辐射为洞察物种多样化及生物多样性模式背后的进化过程提供了独特视角。为了将植物在相似时间段内的多样化情况与近期的丽鱼科鱼类辐射进行比较，丽鱼科鱼类辐射速度比已记录的鸟类、节肢动物和植物辐射快一个数量级，我们聚焦于安第斯山脉的高海拔植物区系，它是所有热带山脉中物种最丰富的。由于安第斯山脉北部近期的隆升，发现大量这种丰富特有植物区系的高地环境自上新世晚期或更新世晚期（200 - 400万年前）才可供殖民。利用DNA序列数据，我们在羽扇豆属内鉴定出一个单系类群，它包含81种安第斯特有的物种。这个分支的年龄估计为118 - 176万年，这意味着其多样化速率为每百万年2.49 - 3.72个物种。这超过了之前对植物的估计，是迄今为止记录到的植物物种爆发式多样化最惊人的例子。此外，这表明丽鱼科鱼类的高多样化速率并非独一无二。与安第斯羽扇豆分支相关的关键创新的缺乏表明，多样化是由安第斯山脉隆升后类似岛屿栖息地出现所带来的生态机会驱动的。来自其他属的数据表明，羽扇豆是安第斯山脉一系列同样快速的植物辐射之一，规模为大陆性且刺激因素类似岛屿，这表明安第斯山脉高海拔植物区系提供了一个在理解快速物种多样化方面可与包括丽鱼科鱼类在内的其他类群相媲美的系统。
