Hodges S A, Arnold M L
Department of Genetics, University of Georgia, Athens 30602.
Proc Natl Acad Sci U S A. 1994 May 24;91(11):5129-32. doi: 10.1073/pnas.91.11.5129.
Species in the columbine genus, Aquilegia, are known for their broad variation in ecology and floral morphology. Aquilegia is also known for the large degree of intercompatibility among its species, which has led to the suggestion that the genus has arisen recently. However, intercompatibility does not always imply recent divergence and the widespread distribution pattern of the genus has suggested an older age. We constructed phylogenies for Aquilegia plus its close relatives by using nucleotide sequence data from both nuclear and chloroplast DNA. The sequence data averaged over 1250 bp per species. Among the 14 columbine species sampled from Europe, Asia, and North America only 16-bp changes and one insertion/deletion event were detected. In contrast, related genera had from 3 to 45 times this level of variation. The phylogenies derived from the chloroplast and nuclear DNA sequences were highly concordant and suggest that the columbines are the result of a recent, rapid radiation. In contrast to other examples of species flocks, Aquilegia has radiated on a widespread geographical scale. By comparison with their related taxa, we suggest that the evolution of the nectar spur in Aquilegia was a key innovation for this genus and allowed rapid speciation through specialization to specific pollinators.
耧斗菜属（Aquilegia）的物种以其在生态和花形态上的广泛变异而闻名。耧斗菜属还因其物种间高度的相互兼容性而为人所知，这导致有人认为该属是最近才出现的。然而，相互兼容性并不总是意味着最近的分化，而且该属广泛的分布模式表明其存在时间更久。我们通过使用来自核DNA和叶绿体DNA的核苷酸序列数据，构建了耧斗菜属及其近缘属的系统发育树。每个物种的序列数据平均超过1250 bp。在从欧洲、亚洲和北美洲采集的14种耧斗菜物种中，仅检测到16个碱基对的变化和1次插入/缺失事件。相比之下，相关属的变异水平是这个数字的3到45倍。从叶绿体和核DNA序列得出的系统发育树高度一致，表明耧斗菜是近期快速辐射的结果。与其他物种群的例子不同，耧斗菜在广泛的地理范围内辐射演化。通过与其相关类群进行比较，我们认为耧斗菜花蜜距的进化是该属的一项关键创新，并通过对特定传粉者的特化实现了快速物种形成。
