Département Milieux et Peuplements Aquatiques, Biologie des Organismes et Écosystèmes Aquatiques, Muséum national d'Histoire naturelle, UMR CNRS-MNHN 7208, CP 26, 57 rue Cuvier, 75231, Paris Cedex 05, France.
Mol Ecol. 2013 Mar;22(6):1518-30. doi: 10.1111/mec.12192. Epub 2013 Jan 7.
Freshwater species on tropical islands face localized extinction and the loss of genetic diversity. Their habitats can be ephemeral due to variability in freshwater run-off and erosion. Even worse, anthropogenic effects on these ecosystems are intense. Most of these species are amphidromous or catadromous (i.e. their life cycle includes a marine larval phase), which buffers them against many of these effects. A long pelagic larval duration (PLD) was thought to be critical to ensure the colonization and persistence in tropical islands, but recent findings indicated that several species with short PLDs are successful in those ecosystems. To test the potential of a short PLD in maintaining genetic connectivity and forestalling extirpation, we studied Kuhlia rupestris, a catadromous fish species with an extensive distribution in the western Pacific and Indian Oceans. Using a combination of molecular genetic markers (13 microsatellite loci and two gene regions from mtDNA) and modelling of larval dispersal, we show that a short PLD constrains genetic connectivity over a wide geographical range. Molecular markers showed that the short PLD did not prevent genetic divergence through evolutionary time and speciation has occurred or is occurring. Modelling of larvae dispersal suggested limited recent connectivity between genetically homogeneous populations across the Coral Sea. However, a short PLD can maintain connectivity on a subocean basin scale. Conservation and management of tropical diadromous species needs to take into account that population connectivity may be more limited than previously suspected in those species.
热带岛屿上的淡水物种面临局部灭绝和遗传多样性丧失。由于淡水径流和侵蚀的变化，它们的栖息地可能是短暂的。更糟糕的是，人为因素对这些生态系统的影响非常强烈。这些物种大多是洄游或溯河产卵的（即它们的生命周期包括一个海洋幼虫阶段），这使它们能够缓冲许多这些影响。人们认为，长的浮游幼体期（PLD）对于确保在热带岛屿上的定居和持续存在至关重要，但最近的研究结果表明，几个具有短 PLD 的物种在这些生态系统中取得了成功。为了测试短 PLD 在维持遗传连通性和防止灭绝方面的潜力，我们研究了 Kuhlia rupestris，这是一种洄游鱼类，分布广泛于西太平洋和印度洋。我们结合使用分子遗传标记（13 个微卫星位点和来自 mtDNA 的两个基因区域）和幼虫扩散模型，表明短 PLD 限制了广泛地理范围内的遗传连通性。分子标记表明，短 PLD 并没有阻止遗传分化随着进化时间的推移发生，而且已经发生或正在发生物种形成。幼虫扩散模型表明，在珊瑚海的遗传上同质种群之间，最近的连通性有限。然而，短 PLD 可以在次大洋盆地范围内维持连通性。对热带洄游物种的保护和管理需要考虑到，与以前的预期相比，这些物种的种群连通性可能更为有限。
