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，会对小型孤立种群产生适合度负面效应；而遗传交流的减弱，亦可能提升局部适应的潜力。本研究针对大西洋全分布区内的中央种群与边缘种群，比较了洞穴珊瑚（Montastraea cavernosa）的遗传多样性与连通性水平。研究对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该珊瑚可划分为3个遗传分化显著的区域：加勒比海-北大西洋区、西南大西洋区（巴西海域）以及东热带大西洋区（西非海域）。各区域内部，种群间的等位基因频率与遗传多样性水平均较为接近；即便种群间距长达3000公里，也未检测到显著遗传分化，表明该珊瑚物种具备长距离扩散的能力。不过，区域内的基因流并未实现整个大西洋海域的连通性。相反，不同区域间的等位基因频率存在显著差异，提示加勒比海、巴西海域与西非海域之间的遗传交流极为稀少。此外，巴西海域与西非海域的种群，其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海-北大西洋种群，孤立的边缘种群更易受到人类活动、疾病或气候变化的威胁。