Hidden ancient diversification in the circumtropical lancelet Asymmetron lucayanum complex
Hidden ancient diversification in the circumtropical lancelet Asymmetron lucayanum complex
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DOI：
10.1007/s00227-006-0271-y
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发表时间：
2006-07-01
期刊：
影响因子：
2.4
通讯作者：
Nishikawa, T.
中科院分区：
文献类型：
--
作者：
Kon, T.;Nohara, M.;Nishikawa, T.
热带文昌鱼 Asymmetron lucayanum (= Epigonichthys lucayanus) 分布于印度洋西部至太平洋中部和大西洋西部。对 A. lucayanum（来自 7 个地点的 80 个样本）线粒体细胞色素 C 氧化酶亚基 I (COI) 序列 (1,035 bp) 的分子系统发育分析清楚地表明，该物种根据使用最大似然距离的邻接树（具有不变位点和伽马校正的 HKY 模型）在遗传上区分为三个主要的地理群体，这表明该物种存在 三个神秘物种。我们的遗传数据表明（1）分支B（中西太平洋）和分支C（大西洋）之间的大洋间分歧时间（d=6.6%，约1200万年前）小于分支A（印度-西太平洋）和分支B之间的大洋内分歧时间（d=39.5%，约1亿年前）； (2)西太平洋有两种同源的隐种； (3) 分支 A 中的马尔代夫和琉球群岛（距离为 10,000 公里）、分支 B 中的菲律宾和夏威夷（距离为 8,500 公里）以及分支 C 中的巴巴多斯和百慕大（距离为 2,200 公里）之间暗示着高基因流。
The tropical lancelet Asymmetron lucayanum (= Epigonichthys lucayanus) is distributed from the western Indian Ocean to the central Pacific Ocean, and the western Atlantic Ocean. Molecular phylogenetic analysis of mitochondrial cytochrome c oxidase subunit I (COI) sequences (1,035 bp) of A. lucayanum (80 specimens from seven localities) showed clearly that this species is genetically distinguished into three major groups of geographical populations based on neighbor-joining tree using maximum likelihood distance (HKY model with invariable sites and gamma correction), suggesting the existence of three cryptic species. Our genetic data show that (1) inter-oceanic divergence time between Clade B (the West-Central Pacific) and Clade C (the Atlantic) (d = 6.6%, ca. 12 million years ago) was smaller than intra-oceanic divergence time between Clade A (the Indo-West Pacific) and Clade B (d=39.5%, ca. 100 million years ago); (2) there are two cryptic species in the West Pacific in sympatry; and (3) high gene flow is implied between the Maldives and the Ryukyus in Clade A (10,000 km distance), the Philippines and Hawaii in Clade B (8,500 km distance), and Barbados and Bermuda in Clade C (2,200 km distance).