Otwoma Levy Michael, Kochzius Marc
Kenya Marine and Fisheries Research Institute, P.O. BOX 81651, Mombasa, Kenya.
Marine Biology, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium.
PLoS One. 2016 Oct 31;11(10):e0165552. doi: 10.1371/journal.pone.0165552. eCollection 2016.
The coral reef sea star Linckia laevigata is common on shallow water coral reefs of the Indo-West Pacific. Its large geographic distribution and comprehensive data from previous studies makes it suitable to examine genetic differentiation and connectivity over large geographical scales. Based on partial sequences of the mitochondrial cytochrome oxidase I (COI) gene this study investigates the genetic population structure and connectivity of L. laevigata in the Western Indian Ocean (WIO) and compares it to previous studies in the Indo-Malay-Philippines Archipelago (IMPA). A total of 138 samples were collected from nine locations in the WIO. AMOVA revealed a low but significant ΦST-value of 0.024 for the WIO populations. In the hierarchical AMOVA, the following grouping rejected the hypothesis of panmixia: (1) Kenya (Watamu, Mombasa, Diani) and Tanzanian Island populations (Misali and Jambiani) and (2) the rest of the WIO sites (mainland Tanzania and Madagascar; ΦCT = 0.03). The genetic population structure was stronger and more significant (ΦST = 0.13) in the comparative analysis of WIO and IMPA populations. Three clades were identified in the haplotype network. The strong genetic differentiation (ΦCT = 0.199, P < 0.001) suggests that Indo-West Pacific populations of L. laevigata can be grouped into four biogeographic regions: (1) WIO (2) Eastern Indian Ocean (3) IMPA and (4) Western Pacific. The findings of this study support the existence of a genetic break in the Indo-West Pacific consistent with the effect of lowered sea level during the Pleistocene, which limited gene flow between the Pacific and Indian Ocean.
光滑斜海星（Linckia laevigata）在印度-西太平洋的浅水珊瑚礁中很常见。其广泛的地理分布以及先前研究的全面数据使其适合用于研究大地理尺度上的遗传分化和连通性。基于线粒体细胞色素氧化酶I（COI）基因的部分序列，本研究调查了西印度洋（WIO）光滑斜海星的遗传种群结构和连通性，并将其与之前在印度-马来-菲律宾群岛（IMPA）的研究进行比较。总共从西印度洋的九个地点收集了138个样本。分子方差分析（AMOVA）显示，西印度洋种群的ΦST值较低但显著，为0.024。在分层分子方差分析中，以下分组拒绝了随机交配的假设：（1）肯尼亚（瓦塔木、蒙巴萨、迪亚尼）和坦桑尼亚岛屿种群（米萨利和詹比阿尼），以及（2）西印度洋的其他地点（坦桑尼亚大陆和马达加斯加；ΦCT = 0.03）。在西印度洋和印度-马来-菲律宾群岛种群的比较分析中，遗传种群结构更强且更显著（ΦST = 0.13）。在单倍型网络中鉴定出三个分支。强烈的遗传分化（ΦCT = 0.199，P < 0.001）表明，光滑斜海星的印度-西太平洋种群可分为四个生物地理区域：（1）西印度洋，（2）东印度洋，（3）印度-马来-菲律宾群岛，以及（4）西太平洋。本研究结果支持了印度-西太平洋存在遗传间断的观点，这与更新世海平面下降的影响一致，海平面下降限制了太平洋和印度洋之间的基因流动。
