Takeuchi Takeshi, Masaoka Tetsuji, Aoki Hideo, Koyanagi Ryo, Fujie Manabu, Satoh Noriyuki
Marine Genomics Unit Okinawa Institute of Science and Technology Graduate University Onna Japan.
Aquaculture Technology Division National Research Institute of Aquaculture, Fisheries Research and Education Agency Tamaki-cho Japan.
Evol Appl. 2020 Jan 8;13(4):837-853. doi: 10.1111/eva.12905. eCollection 2020 Apr.
In the open ocean without terrain boundaries, marine invertebrates with pelagic larvae can migrate long distances using ocean currents, suggesting reduced genetic diversification. Contrary to this assumption, however, genetic differentiation is often observed in marine invertebrates. In the present study, we sought to explain how population structure is established in the western Pacific Ocean, where the strong Kuroshio Current maintains high levels of gene flow from south to north, presumably promoting genetic homogeneity. We determined the population structure of the pearl oyster, , in the Indo-Pacific Ocean using genome-wide genotyping data from multiple sampling localities. Cluster analysis showed that the western Pacific population is distinct from that of the Indian Ocean, and that it is divided into northern (Japanese mainland) and southern (Nansei Islands, China, and Cambodia) populations. Genetic differentiation of can be explained by geographic barriers in the Indian Ocean and a local lagoon, and by environmental gradients of sea surface temperature (SST) and oxygen concentration in the western Pacific. A genome scan showed evidence of adaptive evolution in genomic loci, possibly associated with changes in environmental factors, including SST and oxygen concentration. Furthermore, Bayesian simulation demonstrated that the past population expansion and division are congruent with ocean warming after the last glacial period. It is highly likely that the environmental gradient forms a genetic barrier that diversifies populations in the western Pacific. This hypothesis helps to explain genetic differentiation and possible speciation of marine invertebrates.
在没有地形边界的开阔海洋中，具有浮游幼虫的海洋无脊椎动物可以利用洋流进行长距离迁移，这表明遗传多样性降低。然而，与这一假设相反的是，在海洋无脊椎动物中经常观察到遗传分化。在本研究中，我们试图解释在西太平洋种群结构是如何形成的，在那里强大的黑潮维持着从南到北的高水平基因流动，推测这会促进遗传同质性。我们利用来自多个采样地点的全基因组基因分型数据，确定了印度洋 - 太平洋海域珍珠贝的种群结构。聚类分析表明，西太平洋种群与印度洋种群不同，并且它被分为北部（日本本土）和南部（南西诸岛、中国和柬埔寨）种群。珍珠贝的遗传分化可以由印度洋的地理屏障和一个局部泻湖以及西太平洋海面温度（SST）和氧气浓度的环境梯度来解释。全基因组扫描显示了基因组位点存在适应性进化的证据，这可能与包括SST和氧气浓度在内的环境因素变化有关。此外，贝叶斯模拟表明过去的种群扩张和分化与末次冰期后的海洋变暖是一致的。很有可能环境梯度形成了一个遗传屏障，使西太平洋的珍珠贝种群多样化。这一假设有助于解释海洋无脊椎动物的遗传分化和可能的物种形成。
