Evolutionary changes in geographic distribution and larval host plants may promote the rapid diversification of montane insects, but this scenario has been rarely investigated. We studied rapid radiation of the butterfly genus Colias, which has diversified in mountain ecosystems in Eurasia, Africa, and the Americas. Based on a dataset of 150 nuclear protein-coding genetic loci and mitochondrial genomes, we constructed a time-calibrated phylogenetic tree of Colias species with broad taxon sampling. We then inferred their ancestral geographic ranges, historical diversification rates, and the evolution of host use. We found that the most recent common ancestor of Colias was likely geographically widespread and originated ~3.5 Ma. The group subsequently diversified in different regions across the world, often in tandem with geographic expansion events. No aspect of elevation was found to have a direct effect on diversification. The genus underwent a burst of diversification soon after the divergence of the Neotropical lineage, followed by an exponential decline in diversification rate toward the present. The ancestral host repertoire included the legume genera Astragalus and Trifolium but later expanded to include a wide range of Fabaceae genera and plants in more distantly related families, punctuated with periods of host range expansion and contraction. We suggest that the widespread distribution of the ancestor of all extant Colias lineages set the stage for diversification by isolation of populations that locally adapted to the various different environments they encountered, including different host plants. In this scenario, elevation is not the main driver but might have accelerated diversification by isolating populations.

中文翻译：

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年轻多样的山地蝴蝶属的寄主库和地理范围的快速进化


地理分布和幼虫寄主植物的进化变化可能会促进山地昆虫的快速多样化，但这种情况很少被研究。我们研究了蝴蝶属 Colias 的快速辐射，它在欧亚大陆、非洲和美洲的山地生态系统中多样化。基于 150 个核蛋白编码遗传位点和线粒体基因组的数据集，我们构建了一个具有广泛分类单元采样的 Colias 物种的时间校准系统发育树。然后，我们推断了它们祖先的地理范围、历史上的多样化率和宿主利用的演变。我们发现，大肠杆菌最近的共同祖先可能在地理上广泛分布，起源于~3.5 马。随后，该集团在全球不同地区进行多元化经营，通常与地域扩张活动同时进行。没有发现海拔对多元化有直接影响。在新热带谱系分化后不久，该属经历了一次多元化的爆发，随后到现在的多元化率呈指数级下降。祖先寄主库包括豆科植物 Astragalus 和 Trifolium 属，但后来扩展到包括更广泛的豆科属和更远缘科的植物，穿插着寄主范围扩大和收缩的时期。我们认为，所有现存大肠杆菌谱系的祖先的广泛分布为多样化奠定了基础，通过隔离局部适应它们遇到的各种不同环境（包括不同的寄主植物）的种群。在这种情况下，海拔上升不是主要驱动因素，但可能通过隔离种群加速了多样化。