The evolutionary history of Darwin's finches: speciation, gene flow, and introgression in a fragmented landscape

Many classic examples of adaptive radiations take place within fragmented systems such as islands or mountains, but the roles of mosaic landscapes and variable gene flow in facilitating species diversification is poorly understood. Here we combine phylogenetic and landscape genetic approaches to understand diversification in Darwin's finches, a model adaptive radiation. We combined sequence data from 14 nuclear introns, mitochondrial markers, and microsatellite variation from 51 populations of all 15 recognized species. Phylogenetic species-trees recovered seven major finch clades: ground, tree, vegetarian, Cocos Island, grey and green warbler finches, and a distinct clade of sharp-beaked ground finches (Geospiza cf. difficilis) basal to all ground and tree finches. The ground and tree finch clades lack species-level phylogenetic structure. Interisland gene flow and interspecies introgression vary geographically in predictable ways. First, several species exhibit concordant patterns of ...

众多经典的适应性辐射（adaptive radiation）案例均发生在岛屿、山地等碎片化生境中，但镶嵌式景观与动态基因流在推动物种多样化进程中所发挥的作用，目前仍未得到充分阐释。本研究结合系统发育学与景观遗传学方法，以作为适应性辐射经典研究模型的达尔文雀（Darwin's finches）为研究对象，探究其物种多样化机制。我们整合了15个已确认物种的51个种群的相关数据，包括14个核内含子序列、线粒体标记以及微卫星变异数据。系统发育物种树共鉴定出7个主要的雀类演化支：地雀、树雀、植食树雀、科科斯岛雀、灰莺雀与绿莺雀，以及一支独立的尖嘴地雀（Geospiza cf. difficilis）演化支，该支系位于所有地雀与树雀的基部。地雀与树雀演化支未呈现物种水平的系统发育结构。岛间基因流与种间渐渗现象呈现出具有地理规律性的差异。首先，多个物种呈现出一致的模式……