Data from: Implications of isolation and low genetic diversity in peripheral populations of an amphi-Atlantic coral

Limited dispersal and connectivity in marine organisms can have negative fitness effects in populations that are small and isolated, but reduced genetic exchange may also promote the potential for local adaptation. Here, we compare the levels of genetic diversity and connectivity in the coral Montastraea cavernosa among both central and peripheral populations throughout its range in the Atlantic. Genetic data from one mitochondrial and two nuclear loci in 191 individuals show that M. cavernosa is subdivided into three genetically distinct regions in the Atlantic: Caribbean-North Atlantic, Western South Atlantic (Brazil) and Eastern Tropical Atlantic (West Africa). Within each region, populations have similar allele frequencies and levels of genetic diversity; indeed, no significant differentiation was found between populations separated by as much as 3,000 km, suggesting that this coral species has the ability to disperse over large distances. Gene flow within regions does not, however, translate into connectivity across the entire Atlantic. Instead, substantial differences in allele frequencies across regions suggest that genetic exchange is infrequent between the Caribbean, Brazil and West Africa. Furthermore, markedly lower levels of genetic diversity are observed in the Brazilian and West African populations. Genetic diversity and connectivity may contribute to the resilience of a coral population to disturbance. Isolated peripheral populations may be more vulnerable to human impacts, disease or climate change relative to those in the genetically diverse Caribbean-North Atlantic region.海洋生物的有限扩散与连通性，会对小型且孤立的种群产生适合度负面效应，但遗传交流的减弱也可能推动本地适应的潜能。本文针对大西洋分布范围内的中央种群与边缘种群，对比分析了簇柱珊瑚（Montastraea cavernosa）的遗传多样性与连通性水平。研究针对191个个体的1个线粒体位点与2个核位点开展遗传分析，结果显示大西洋海域的簇柱珊瑚可划分为3个遗传分化显著的区域：加勒比-北大西洋区域、西南大西洋区域（巴西海域）以及东热带大西洋区域（西非海域）。各区域内部的种群拥有相近的等位基因频率与遗传多样性水平；实际上，即便种群间距长达3000公里，也未检测到显著的遗传分化，这表明该珊瑚物种具备长距离扩散的能力。不过，区域内部的基因流并未延伸至整个大西洋海域形成连通性。相反，不同区域间等位基因频率存在显著差异，表明加勒比、巴西与西非海域的种群间遗传交流十分有限。此外，巴西与西非海域的种群遗传多样性水平显著偏低。遗传多样性与连通性或可提升珊瑚种群应对扰动的恢复力。相较于遗传多样性丰富的加勒比-北大西洋区域种群，孤立的边缘种群更易受到人类活动、疾病或气候变化的影响。