Department of Biology, Faculty of Sciences, University of Isfahan, Isfahan, 81746-73441, Iran.
Botany Research Division, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), 13185-116, Tehran, Iran.
Sci Rep. 2017 Oct 25;7(1):14033. doi: 10.1038/s41598-017-14614-3.
The taxa of Astragalus section Hymenostegis are an important element of mountainous and steppe habitats in Southwest Asia. A phylogenetic hypothesis of sect. Hymenostegis has been obtained from nuclear ribosomal DNA internal transcribed spacer (ITS) and plastid ycf1 sequences of up to 303 individuals from 106 species, including all 89 taxa currently assigned to sect. Hymenostegis, 14 species of other Astragalus sections, and two species of Oxytropis and one Biserrula designated as outgroups. Bayesian phylogenetic inference and parsimony analyses reveal that three species from two other closely related sections group within sect. Hymenostegis, making the section paraphyletic. DNA sequence diversity is generally very low among Hymenostegis taxa, which is consistent with recent diversification of the section. We estimate that diversification in sect. Hymenostegis occurred in the middle to late Pleistocene, with many species arising only during the last one million years, when environmental conditions in the mountain regions of Southwest and Central Asia cycled repeatedly between dry and more humid conditions.
紫云英属（Astragalus）节段密花组的分类群是亚洲西南部山地和草原生境的重要组成部分。通过对核核糖体 DNA 内转录间隔区（ITS）和多达 303 个个体的质体 ycf1 序列的分析，获得了节段密花组的系统发育假说，其中包括目前分配给节段密花组的 89 个分类群、14 个其他紫云英属节段的物种以及作为外群的两种 Oxytropis 和一种 Biserrula。贝叶斯系统发育推断和简约分析表明，来自两个其他密切相关节段的三个物种属于节段密花组，使得该组为并系群。节段密花组的 DNA 序列多样性通常非常低，这与该组最近的多样化是一致的。我们估计，节段密花组的多样化发生在更新世中期至晚期，许多物种仅在过去 100 万年中出现，当时亚洲西南部和中部山区的环境条件在干燥和更湿润的条件之间反复循环。
