Multiple origins of two Ochrosia (Apocynaceae) species endemic to the Bonin (Ogasawara) Islands
Multiple origins of two Ochrosia (Apocynaceae) species endemic to the Bonin (Ogasawara) Islands
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小笠原群岛特有的两种 Ochrosia（夹竹桃科）物种的多重起源
DOI：
10.1016/j.ympev.2022.107455
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发表时间：
2022
影响因子：
4.1
通讯作者：
Takayama Koji
中科院分区：
文献类型：
--
作者：
Noda Hiroshi;Nishimura Akihiro;Kato Hidetoshi;Naiki Akiyo;Xiao Wei;Martinez Mario;Marutani Mari;McConnell James;Takayama Koji
Ochrosia广泛分布于西印度洋、热带亚洲和中南太平洋地区，其中有许多岛屿特有种，这表明长距离扩散和迁移后的隔离是阐明Ochrosia多样化过程的关键因素。然而，由于很难从该属的整个分布范围内进行足够的取样，因此对特有的Ochrosiaspecies的系统发育和系统地理学没有进行很好的评价。本研究以西北太平洋小笠原群岛特有的两种白蜡虫为研究对象。小笠原群岛由小笠原群岛和火山群岛两个岛屿群组成，相距约300公里。火山群岛群特有的一种。为了阐明这两个特有的Ochrosiaspecies的系统发育位置，我们进行了分子系统发育研究，包括其他Ochrosiaspecies的断代和电泳分析。系统发育树显示两种特有种起源不同; nakaiana与O. oppositifoliaandO. Iwasakiana，whereasO. hexandra与O. mariannensis。基于叶绿体DNA的同源性，3660万年前，赭属分为两个主要的谱系。此外，小笠原群岛的两个特有种在大约100 - 200万年前是独立衍生的。Ochrosia nakaiana起源于东南亚、新喀里多尼亚或其他太平洋岛屿，而O.己烷衍生自O.密克罗尼西亚的马里亚纳群岛。我们证明了小笠原群岛上两种特有的Ochrosiaspecies的不同起源。该研究为大洋岛屿植物群的复杂起源和物种形成提供了一个很好的例子。
The genus,Ochrosia, is widely distributed from the West Indian Ocean throughout tropical Asia to the Middle Southern Pacific region.Ochrosiacomprises many island-endemic species, suggesting that long-distance dispersal and isolation after migration are key factors for clarifying the diversification process. However, the phylogeny and biogeography of endemicOchrosiaspecies have not been evaluated well due to the difficulty of adequate sampling from the entire distribution range of the genus. In this study, we focused on twoOchrosiaspecies endemic to the Bonin (Ogasawara) Islands in the northwest Pacific. The Bonin Islands are of volcanic origins and consist of two islands groups, the Ogasawara and Volcano Islands groups, approximately 300 km apart.Ochrosia nakaianais endemic to the Ogasawara Islands group, whereasO. hexandrais endemic to the Volcano Islands group. To elucidate the phylogenetic positions of these two endemicOchrosiaspecies, we conducted molecular phylogenetic studies with dating and biogeographic analyses including otherOchrosiaspecies. The phylogenetic trees showed that the two endemic species had distinct origins;O. nakaianawas closely related toO. oppositifoliaandO. iwasakiana, whereasO. hexandrawas related toO. mariannensis. Based on the chloroplast DNA phylogeny, the genus,Ochrosia, divided into two major lineages 36.6 million years ago. Further, the two endemic species of the Bonin Islands were independently derived approximately 1–2 million years ago.Ochrosia nakaianaoriginated from the Southeast Asia, New Caledonia, or other Pacific Islands, whileO. hexandraderived fromO. mariannensisin Micronesia. We demonstrated different origins of the two endemicOchrosiaspecies on the Bonin Islands. This study provided an excellent example of the complex origins and speciation of flora in the oceanic islands.