Connectivity of Caribbean coral populations: complementary insights from empirical and modelled gene flow

Understanding patterns of connectivity among populations of marine organisms is essential for the development of realistic, spatially explicit models of population dynamics. Two approaches, theoretical and empirical population genetic models, have been used to estimate levels of evolutionary connectivity among marine populations but rarely have their potentially-complementary insights been combined. Here, a spatially-realistic Lagrangian model of larval dispersal and a theoretical genetic model are integrated with the most extensive study of gene flow in a Caribbean marine organism. The 871 genets collected from 26 sites spread over the wider Caribbean sub-sampled 45.8% of the 1900 potential unique genets in the model. At a coarse scale, significant consensus between modelled estimates of genetic structure and empirical genetic data for populations of the reef-building coral Montastraea annularis is observed. However, modelled and empirical data differ in their estimates of connectivity among northern Mesoamerican reefs indicating that processes other than dispersal may dominate here. Further, the geographic location and porosity of the previously described east-west barrier to gene flow in the Caribbean is refined. A multi-prong approach, integrating genetic data and spatially-realistic models of larval dispersal and genetic projection, provides complementary insights into the processes underpinning population connectivity in marine invertebrates on evolutionary timescales.

解析海洋生物种群间的连通模式，对于构建兼具真实性与空间显式（spatially explicit）特征的种群动态模型至关重要。当前学界常通过理论种群遗传模型与经验种群遗传模型两种途径，估算海洋种群间的进化连通水平，但极少将二者潜在的互补研究视角相结合。
本研究将兼具空间真实性的幼虫扩散拉格朗日（Lagrangian）模型与理论遗传模型，与针对加勒比海某海洋生物迄今规模最大的基因流研究相结合。研究团队从遍布整个加勒比海区域的26个采样位点中收集了871个遗传株，该样本覆盖了模型中1900个潜在唯一遗传株的45.8%。在粗尺度下，造礁珊瑚环形菊珊瑚（Montastraea annularis）种群的模型遗传结构估算结果，与经验遗传数据间存在显著一致性。但在中美洲北部珊瑚礁群的连通性估算上，模型数据与经验数据存在显著差异，这表明除扩散过程外，其他过程可能在该区域占据主导地位。此外，本研究还细化了此前被报道的加勒比海东西向基因流屏障的地理分布与通透特性。
这种整合了遗传数据、空间显式幼虫扩散模型与遗传预测模型的多维度研究途径，为解析演化时间尺度下海洋无脊椎动物种群连通性的核心驱动过程提供了互补性研究视角。