Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK.
Laboratorio de Botánica y Sistemática, Departamento de Ciencias Biológicas, Universidad de los Andes, Apartado Aéreo, 4976, Bogotá, Colombia.
New Phytol. 2018 Jul;219(2):779-793. doi: 10.1111/nph.15243. Epub 2018 Jun 4.
Mountain ranges are amongst the most species-rich habitats, with many large and rapid evolutionary radiations. The tempo and mode of diversification in these systems are key unanswered questions in evolutionary biology. Here we study the Andean Lupinus radiation to understand the processes driving very rapid diversification in montane systems. We use genomic and transcriptomic data of multiple species and populations, and apply phylogenomic and demographic analyses to test whether diversification proceeded without interspecific gene flow - as expected if Andean orogeny and geographic isolation were the main drivers of diversification - or if diversification was accompanied by gene flow, in which case other processes were probably involved. We uncover several episodes of gene flow between species, including very recent events likely to have been prompted by changes in habitat connectivity during Pleistocene glacial cycles. Furthermore, we find that gene flow between species was heterogeneously distributed across the genome. We argue that exceptionally fast diversification of Andean Lupinus was partly a result of Late Pleistocene glacial cycles, with associated cycles of expansion and contraction driving geographic isolation or secondary contact of species. Furthermore, heterogeneous gene flow across the genome suggests a role for selection and ecological speciation in rapid diversification in this system.
山脉是物种最丰富的栖息地之一，有许多大型和快速的进化辐射。这些系统中的多样化速度和模式是进化生物学中未解决的关键问题。在这里，我们研究安第斯山 Lupinus 辐射，以了解驱动山地系统快速多样化的过程。我们使用多个物种和种群的基因组和转录组数据，并应用系统发育基因组学和种群动态分析来检验多样化是否在没有种间基因流的情况下进行——如果安第斯造山运动和地理隔离是多样化的主要驱动因素，这是可以预期的——还是多样化伴随着基因流，如果是这样，可能涉及其他过程。我们发现了几个物种之间的基因流事件，包括在更新世冰期期间栖息地连通性发生变化时可能发生的非常近期的事件。此外，我们发现种间基因流在基因组中分布不均匀。我们认为，安第斯山 Lupinus 的异常快速多样化部分是晚更新世冰期循环的结果，相关的扩张和收缩循环驱动了物种的地理隔离或二次接触。此外，基因组中不均匀的基因流表明选择和生态物种形成在该系统的快速多样化中发挥了作用。
