An understanding of how genetic variability is distributed in space is fundamental for the conservation and maintenance of diversity in spatially fragmented and vulnerable populations. While fragmentation can occur from natural barriers, it can also be exacerbated by anthropogenic activities such as hydroelectric power plant development. Whatever the source, fragmentation can have significant ecological effects, including disruptions of migratory processes and gene flow among populations. In Chile, the Biobío River basin exhibits a high degree of habitat fragmentation due to the numerous hydroelectric power plants in operation, the number of which is expected to increase following new renewable energy use strategies. Here, we assessed the effects of different kinds of barriers on the genetic structure of the endemic freshwater fish Percilia irwini, knowledge that is critically needed to inform conservation strategies in light of current and anticipated further fragmentation initiatives in the system. We identified eight genetic units throughout the entire Biobío system with high effective sizes. A reduced effective size estimate was, however, observed in a single population located between two impassable barriers. Both natural waterfalls and human‐made dams were important drivers of population differentiation in this system; however, dams affect genetic diversity differentially depending on their mode of operation. Evidence of population extirpation was found in two river stretches limited by upstream and downstream dams. Significant gene flow in both directions was found among populations not separated by natural or anthropogenic barriers. Our results suggest a significant vulnerability of P. irwini populations to future dam development and demonstrate the importance of studying basin‐wide data sets with genetic metrics to understand the strength and direction of anthropogenic impacts on fish populations.

中文翻译：

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人类引起的栖息地破碎化对比奥比奥河流域（智利）特有鱼类 Percilia irwini 的连通性、多样性和种群持续性的影响

了解遗传变异在空间中的分布对于保护和维持空间分散和脆弱群体的多样性至关重要。虽然自然屏障可能导致碎片化，但水力发电厂开发等人为活动也可能加剧碎片化。无论来源如何，碎片化都会产生重大的生态影响，包括破坏迁徙过程和种群之间的基因流动。在智利，由于大量正在运行的水力发电厂，比奥比奥河流域表现出高度的栖息地破碎化，随着新的可再生能源利用战略的实施，预计水力发电厂的数量还会增加。在这里，我们评估了不同类型的障碍对特有淡水鱼Percilia irwini遗传结构的影响，根据系统中当前和预期的进一步破碎举措，这些知识对于为保护策略提供信息至关重要。我们在整个 Biobío 系统中确定了 8 个具有高有效大小的遗传单元。然而，在位于两个不可逾越的障碍之间的单个种群中观察到有效大小估计值减少。天然瀑布和人造水坝都是该系统中人口分化的重要驱动因素。然而，水坝对其遗传多样性的影响有所不同，具体取决于其运作方式。在受上游和下游水坝限制的两条河段中发现了人口灭绝的证据。在未被自然或人为障碍分隔的人群中发现了显着的双向基因流动。我们的结果表明， P. irwini种群对未来大坝开发的显着脆弱性，并证明了利用遗传指标研究全流域数据集以了解人为对鱼类种群影响的强度和方向的重要性。