• 1. Freshwater ecosystems worldwide harbour disproportionately high numbers of endemic species under threat from human activity, particularly accelerated habitat fragmentation. The Murray–Darling Basin in south‐eastern Australia, one of the country's largest and arguably its most vulnerable freshwater ecosystem, is inhabited by a number of small‐bodied fishes that are threatened with imminent extinction.
• 2. Here an extensive microsatellite dataset was used, supplemented by additional allozyme and mitochondrial DNA analyses, to assess the genetic diversity, population structure and contemporary migration patterns in the Murray hardyhead Craterocephalus fluviatilis, one of Australia's most threatened fishes.
• 3. Genetic diversity estimates, primarily based on 413 fish collected during the latter period of intense drought (1997–2010) from 23 sites and genotyped at 14 microsatellite loci, were higher than those previously detected for other regionally co‐occurring small‐bodied freshwater fishes.
• 4. Population structure analyses identified a subtle primary split between ‘lower Murray’ (lower river reaches) versus ‘upstream Murray’ (upper river reaches) and a total of nine genetically similar sub‐populations. This includes unexpected sub‐population differentiation in the Lower Lakes, a region at the terminus of the Murray–Darling Basin that most often has inter‐connected habitat.
• 5. Very low levels of contemporary migration were detected between most inferred populations (<2%) during the drought, with all exceptions involving moderate levels of migration from an upstream sub‐population into an adjacent downstream sub‐population.
• 6. This article describes how these genetic data have guided translocation and reintroduction efforts in recent years. We advocate the use of assisted gene flow as a central component of continuing efforts to rescue this species from imminent extinction.

中文翻译：

---

范围广泛的人群遗传学研究为濒危的Murray硬头（Craterocephalus fluviatilis）的保护易位和重新引入提供了信息

• 1.世界范围内的淡水生态系统在人类活动的威胁下，尤其是加速生境破碎化的地方，拥有大量的地方特有物种。澳大利亚东南部的默里-达令盆地是澳大利亚最大，可能是最脆弱的淡水生态系统之一，栖息着许多濒临灭绝的小鱼。
• 2.在这里，我们使用了一个广泛的微卫星数据集，辅以其他的同工酶和线粒体DNA分析，以评估澳大利亚最受威胁的鱼类之一的Murray hardyhead Craterocephalus fluviatilis的遗传多样性，种群结构和当代迁移模式。
• 3.遗传多样性估计数主要基于后期干旱期间（1997-2010年）从23个地点收集的413条鱼并在14个微卫星基因座处进行基因分型，比先前在其他区域同时存在的小体淡水中发现的值高。鱼。
• 4.人口结构分析确定了“下游墨累”（下游河段）与“上游墨累”（上游河段）之间的细微主要区别，共有九个遗传相似的亚群。这包括在下湖（Murray-Darling盆地末端的一个区域，该区域最常具有相互联系的栖息地）中的意料之外的亚群分化。
• 5.在干旱期间，在大多数推断人群之间发现的当代移民水平非常低（<2％），所有例外情况都涉及从上游亚种群向邻近的下游亚种群的中等程度的移民。
• 6.本文介绍了近年来这些遗传数据如何指导易位和再引入工作。我们提倡使用辅助基因流作为继续努力挽救该物种免于灭绝的持续努力的重要组成部分。