Data from: Landscape genetics informs mesohabitat preference and conservation priorities for a surrogate indicator species in a highly fragmented river system

Poor dispersal species represent conservative benchmarks for biodiversity management because they provide insights into ecological processes influenced by habitat fragmentation that are less evident in more dispersive organisms. Here we used the poorly dispersive and threatened river blackfish (Gadopsis marmoratus) as a surrogate indicator system for assessing the effects of fragmentation in highly modified river basins and for prioritizing basin-wide management strategies. We combined individual, population and landscape-based approaches to analyze genetic variation in samples spanning the distribution of the species in Australia’s Murray–Darling Basin, one of the world’s most degraded freshwater systems. Our results indicate that G. marmoratus displays the hallmark of severe habitat fragmentation with notably scattered, small and demographically isolated populations with very low genetic diversity—a pattern found not only between regions and catchments but also between streams within catchments. By using hierarchically nested population sampling and assessing relationships between genetic uniqueness and genetic diversity across populations, we developed a spatial management framework that includes the selection of populations in need of genetic rescue. Landscape genetics provided an environmental criterion to identify associations between landscape features and ecological processes. Our results further our understanding of the impact that habitat quality and quantity has on habitat specialists with similarly low dispersal. They should also have practical applications for prioritizing both large- and small-scale conservation management actions for organisms inhabiting highly fragmented ecosystems.扩散能力较弱的物种是生物多样性管理中的保守基准类群，因其能揭示生境破碎化影响下的生态过程——这类过程在扩散能力更强的类群中往往较难被观测到。本研究以扩散能力弱且受威胁的河黑体鱼（Gadopsis marmoratus）作为替代指示系统，用于评估高度人工改造河流流域的破碎化效应，并制定全流域管理策略的优先级排序。我们结合个体、种群及景观层面的分析方法，对澳大利亚墨累-达令盆地（Murray–Darling Basin）——全球退化程度最严重的淡水生态系统之一——内覆盖该物种全部分布范围的样本开展遗传变异分析。研究结果显示，河黑体鱼呈现出严重生境破碎化的典型特征：种群分布极为零散、规模狭小且种群间在人口统计学上相互隔离，同时遗传多样性水平极低——这种分布模式不仅存在于不同区域与集水区之间，也出现在集水区内部的溪流之间。通过采用层级嵌套种群采样策略，并评估种群间遗传独特性与遗传多样性的关联，我们构建了一套空间管理框架，其中涵盖了需要实施遗传拯救的种群筛选。景观遗传学（Landscape genetics）提供了一种环境判别准则，用以识别景观特征与生态过程之间的关联。本研究增进了我们对生境质量与数量如何影响同类低扩散能力生境专性物种的理解，同时可为高度破碎化生态系统中栖息生物的大、小型保护管理行动优先级划分提供实践指导。