Phylogenetic divergence is associated with biogeographic divergence in sect. <i>Hymenobrychis</i> (<i>Onobrychis</i>, Fabaceae): molecular phylogenetic and morphological evidence

Identifying the factors that drive high diversity in global biodiversity hotspots requires sound hypotheses on the phylogenetic relationships of the constituent lineages. For the Irano-Anatolian biodiversity hotspot, molecular phylogenetic hypotheses for many lineages are still lacking. One of these understudied groups is sect. <i>Hymenobrychis</i> (<i>Onobrychis</i>, Fabaceae). This group comprises predominantly perennials jointly ranging from Central Asia to southern Europe and northeastern Africa. Here, we use a nuclear ribosomal DNA internal transcribed spacer and three non-coding plastid sequences to test the monophyly of the section and its subsectional divisions as well as to resolve interspecific relationships. Phylogenetic analyses (maximum parsimony, maximum likelihood, and Bayesian inference) of the combined data set supported the monophyly of sect. <i>Hymenobrychis</i> after the exclusion of the Central Asian <i>O. dushanbensis</i>, which, based on molecular and morphological evidence, is similar to <i>O. grandis</i> of sect. <i>Lipskyanae</i>. Furthermore, <i>O</i>. subsect. <i>Pulcherrimae</i> was found to be paraphyletic due to the nested position of <i>O. ptolemaica</i>, the sole included member of subsect. <i>Modestae</i>. Divergence of the main clades within the sect. <i>Hymenobrychis</i> was associated with geographic divergence via dispersal and/or vicariance from Central Asia, where the section originated, westwards via Transcaucasia, the area with the highest species richness, to southern Europe, Mesopotamia, and northeastern Africa.

探明全球生物多样性热点区域的高多样性驱动因子，有赖于针对其组成支系系统发育关系的严谨假说。针对伊朗-安纳托利亚生物多样性热点区域而言，目前仍缺乏多数类群的分子系统发育假说。此类尚未得到充分研究的类群之一，即为豆科（Fabaceae）驴食草属（Onobrychis）的膜苞组（sect. Hymenobrychis）。该类群以多年生植物为主，分布范围从中亚延伸至南欧与东北非。本研究采用核糖体DNA内部转录间隔区（nuclear ribosomal DNA internal transcribed spacer）与3个非编码质体序列，检验该组及其亚组划分的单系性，并解析其物种间的系统发育关系。对合并数据集开展的系统发育分析（包含最大简约法、最大似然法与贝叶斯推断）结果显示：剔除中亚产的杜尚别驴食草（O. dushanbensis）后，膜苞组（sect. Hymenobrychis）符合单系性；基于分子与形态学证据，该物种与Lipskyanae组（sect. Lipskyanae）的大驴食草（O. grandis）亲缘关系相近。此外，美丽亚组（subsect. Pulcherrimae）被证实为并系群：作为Modestae亚组（subsect. Modestae）唯一纳入本研究的类群，O. ptolemaica嵌套于美丽亚组内部。膜苞组内主要进化支的分化，与该类群的地理演化路径紧密相关：该组起源于中亚，随后通过扩散和/或异域分化向西扩散，途经物种丰富度最高的外高加索（Transcaucasia）地区，最终抵达南欧、美索不达米亚与东北非。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于豆科植物sect. Hymenobrychis的系统发育和生物地理学研究，通过分子和形态学证据分析其单系性和物种关系。研究发现该组主要分支的演化与地理扩散或隔离相关，起源于中亚并西向扩散至高加索、南欧等地区，为伊朗-安纳托利亚生物多样性热点区的演化机制提供了新见解。