热带海洋学报

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海南岛岸礁澄黄滨珊瑚(Porites lutea)集合种群的遗传结构和连通性

付成冲1, #, 李福宇1, #, 陈丹丹2, 侯敬1, 王珺1, 李元超2, 王道儒2, 王嫣1   

  1. 1. 海南大学海洋学院, 海南 海口 570228;

    2. 海南省海洋与渔业科学院, 海南 海口 571199

  • 收稿日期:2022-05-04 修回日期:2022-05-13 出版日期:2022-05-16 发布日期:2022-05-16
  • 通讯作者: 王嫣
  • 基金资助:
    国家自然科学基金(41376174); 海南省重点研发计划项目(ZDYF2018108); 国家重点研发计划 (2018YFC1406504)

The genetic structure and connectivity of Porites lutea metapopulation of the fringing reefs around Hainan Island

FU Chengchong1#, LI Fuyu1#, CHEN Dandan2, HOU Jing1, WANG Jun1, LI Yuanchao2, WANG Daoru2, WANG Yan1   

  1. 1. State Key Laboratory of Marine Resource Utilization in South China Sea, Key Laboratory of Tropical Hydrobiology and Biotechnology of Hainan Province, College of Marine Sciences, Hainan University, Haikou 570228, China;

    2. Hainan Academy of Ocean and Fisheries Sciences, Haikou 571199, China

  • Received:2022-05-04 Revised:2022-05-13 Online:2022-05-16 Published:2022-05-16
  • Contact: WANG Yan
  • Supported by:

    National Natural Science Foundation of China (41376174); Key Research and Development Program of Hainan Province (ZDYF2018108); National Key Research and Development Program of China (2018YFC1406504)

摘要: 海南岛岸礁的造礁珊瑚代表性种类澄黄滨珊瑚(Porites lutea)是环境适应性较强的块状产卵型珊瑚。探究其遗传结构和连通性将有助于揭示其海南岛岸礁集合种群的遗传多样性格局和幼虫迁移路径, 进而阐明海南珊瑚礁的恢复潜力。本研究通过11个P. lutea微卫星标记来分析10个海南岛岸礁地理群体和1个西沙群岛(XsR)群体的遗传结构。结果显示, 整体上各群体的遗传多样性中等偏低, 平均等位基因丰度Rs (allelic richness)为2.8 ± 1.3 (八所群体, Bs) - 3.7 ± 1.7 (邻昌礁群体, LcR), 平均观测杂合度和期望杂合度分别为0.31(铜鼓岭群体, Tgl) - 0.54 (大铲礁群体, DcR)和0.50 (雷公岛群体, LgI) -0.64 (海尾群体, Hw)。除海南岛东部龙湾群体(LwR)、大洲岛群体(DzI)和西部的八所(Bs)、大铲礁(DcR)群体之外, 7/11的地理群体均呈杂合子缺失。海南岛岸礁澄黄滨珊瑚P. lutea地理群体间的遗传分化显示, 集合种群分为北东南遗传连通带和西岸两支, 支间遗传分化显著。前者包括北岸的雷公岛群体和木栏头群体、东岸的大洲岛群体, 以及南岸的鹿回头和八所群体。由于珊瑚幼虫随海流迁移而形成的有效的基因流, 消弭了它们之间的遗传分化。而西岸群体因北部湾沿岸海流交换不畅, 与外部的基因交流受阻。西岸的海尾群体与西南部的八所群体间尽管相距不足50 km, 但遗传分化明显。这可能是由于昌化江径流形成的盐度波动和悬浮沉积物的隔离作用。同样, 铜鼓岭群体因处于铜鼓岭岬角内波影区, 其南部八门湾径流或限制了它与东岸群体的基因交流, 因而呈现近交、低杂合度和非随机交配特性。此外, 或由对离岸礁坡环境的趋同适应, 东岸龙湾群体与西岸的离岸岛礁邻昌礁群体、大铲礁群体和海尾群体之间的遗传相似性更高。以P. lutea集合种群为代表的海南岛珊瑚岸礁有着相对充沛的基因交流, 且因受海流、径流及复杂岸礁环境影响而形成了多层次的遗传分化和基因流格局, 这构成其应对外界胁迫的主要自然恢复力。西沙群体与海南岛岸礁群体之间的遗传分化较大, 呈现显著的地理隔离。西沙七连屿可能由于自身珊瑚礁健康状况的衰退而丧失了对海南岛珊瑚幼虫的补充能力。

关键词: 澄黄滨珊瑚, 遗传连通性, 微卫星标记, 径流, 岸礁结构, 海流

Abstract: Porites lutea, the representative species of reef building corals around Hainan Island, is a spawning, massive coral with strong environmental adaptability. Exploring the genetic structure and connectivity of this species will help to reveal the genetic diversity pattern and larval migration path of coral metapopulation around Hainan Island, thus clarifying the recovery potential of coral reefs. In this study, 11 P. lutea microsatellite markers were screened to analyze the genetic structure of 10 populations of Hainan fringing reefs and 1 population (XsR) in Xisha Islands. The results showed that, overall the genetic diversity of all populations was medium to low, with the average allelic richness Rs ranged from 2.8 ± 1.3 (Basuo population, Bs) to 3.7 ± 1.7 (Linchang Reef population, LcR), and the average observed and expected heterozygosity ranged from 0.31 (Tongguling population, Tgl) to 0.54 (Dachan Reef population, DcR) and 0.50 (Leigong Island population, LgI) to 0.64 (Haiwei population, Hw), respectively. Except for Longwan Reef population (LwR) and Dazhou Island population (DzI), which located in the east of Hainan Island, and Basuo population (Bs) and Dachan Reef population (DcR (in the west of Hainan Island), all other populations (7/11) showed evidence of heterozygote deficiency. According to genetic differentiation, Hainan Island populations were divided into two groups: the north-south-east genetically connected zone and the west coast, and the differentiation between the two branches (AMOVA, 0.092) was significant. The former group included Bs, Luhuitou population (Lht), DzI, LgI and Mulantou population (Mlt), due to the significant gene flow created by exchange of ocean currents, there was no obvious genetic differentiation among these five coastal populations, whereas the gene flow of the offshore populations (LcR, DcR and Hw) of the west coast was blocked due to the discontinuity of coastal reefs and slow coastal currents. LwR in the east coast also converges to the west branch, which may be due to the isolation by environment and the convergent adaptation to offshore environment. Although the distance between Hw and Bs is less than 50 km, but they are obviously differentiated, possibly due to the isolation by salinity fluctuation and suspended sediments caused by the runoff of Changhua River. Tgl showed strong inbreeding, low heterozygosity and non-random mating characteristics because it was located in the wave shadow area of Tongguling headland, and the runoff of Bamen River restricted its gene exchange with other coastal reef populations. Represented by P. lutea metapopulations, the fringing reefs of Hainan Island has the natural resilience responding to environmental stress due to the strong gene flow and the genetic differentiation caused by ocean current, runoff and complex fringing reef structure, as well as the environmental differences between nearshore and offshore. The genetic differentiation between Xisha Islands population and the coastal reef populations of Hainan Island was large, showing significant geographical isolation. Qilianyu Island may have lost the ability to replenish Hainan Island with coral larvae because the coral reefs there have declined.

Key words: Porites lutea, Genetic connectivity, Microsatellite marker, Runoff, Fringing reef structures, Currents