Aim: Studying clearly delineated populations in marine lakes, islands of sea, we investigated the interplay of habitat size, dispersal potential, and priority effects in shaping marine population genetic structure. Location: Marine lakes and coastal locations in Indonesia, Palau, Papua New Guinea and Australia. Taxon: Mussels (Mytilidae, Brachidontes spp.) Methods: Populations were sampled from four coastal locations and 22 marine lakes of similar age (~8,000 years), yet differing in size (0.04–4.7 km2) and degree of connection to the adjacent sea. While some lakes are highly connected, allowing potential influx of larvae from the sea, others have very limited water exchange. We assessed the phylogeographical structure and demographic history using mitochondrial and nuclear DNA sequence data, and combined this with geometric morphometrics. The effects of lake characteristics on population genetic diversity and structure were tested using linear regression and Mantel tests. Results: Each lake contained one of six distinct genetic lineages, which were characterized by deep phylogenetic splits and significant morphometric differences. These lineages likely represent separate species. The lineages showed similar demographic patterns, with lakes containing founder populations that rapidly expanded and diverged. Genetic diversity within lake populations was significantly correlated with lake area, but not with physical connection to the adjacent sea. Within lineages that occurred in multiple lakes there was strong population structure (average ΦST 0.65), which did not conform to an isolation‐by‐distance pattern or to the degree of dispersal potential. Main Conclusions: Marine lakes across a gradient of physical isolation show strong population structure and evidence for in situ divergence. We hypothesize that the observed genetic structure is the result of priority effects. In addition, reduction of habitat size appears to reduce genetic diversity, even at very small spatial scales. Our findings are relevant in the context of ongoing alterations to coastal hydrodynamics, which lead to habitat reduction and influence migration among populations at fine spatial scales.

中文翻译：

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先到先得：在不同程度的扩散潜力下，优先效应对海洋种群的可能作用

目的：研究海洋湖泊、海洋岛屿中明确划分的种群，我们研究了栖息地大小、扩散潜力和塑造海洋种群遗传结构的优先效应之间的相互作用。位置：印度尼西亚、帕劳、巴布亚新几内亚和澳大利亚的海洋湖泊和沿海地区。分类群：贻贝（贻贝科、贻贝属） 方法：从四个沿海地区和 22 个年龄相近（约 8,000 年）但大小（0.04-4.7 平方公里）和与邻近海域连接程度不同的海洋湖泊中取样. 虽然一些湖泊高度相连，允许幼虫从海洋中涌入，但其他湖泊的水交换非常有限。我们使用线粒体和核 DNA 序列数据评估了系统地理学结构和人口统计历史，并将其与几何形态测量学相结合。湖泊特征对种群遗传多样性和结构的影响使用线性回归和曼特尔检验进行测试。结果：每个湖泊都包含六个不同的遗传谱系之一，其特征是系统发育深度分裂和形态测量差异显着。这些谱系可能代表不同的物种。这些谱系显示出类似的人口模式，湖泊中的创始人种群迅速扩大和分化。湖泊种群内的遗传多样性与湖泊面积显着相关，但与邻近海域的物理联系无关。在发生在多个湖泊的谱系中，存在强烈的种群结构（平均 ΦST 0.65），这不符合按距离隔离的模式或分散潜力的程度。主要结论：跨越物理隔离梯度的海洋湖泊显示出强大的种群结构和就地分化的证据。我们假设观察到的遗传结构是优先效应的结果。此外，即使在非常小的空间尺度上，栖息地大小的减少似乎也会减少遗传多样性。我们的研究结果与沿海水动力持续变化的背景相关，这导致栖息地减少并影响精细空间尺度上的种群迁移。