Understanding connectivity is crucial for the effective conservation and management of biota. However, measuring connectivity directly is challenging and it is often inferred based on assumptions surrounding dispersal potential, such as environmental history and species life history traits. Genetic tools are often underutilised, yet can infer connectivity reliably. Here, we characterise and compare the genetic connectivity and genetic diversity of three diadromous Australian fish species: common galaxias (Galaxias maculatus), tupong (Pseudaphritis urvillii) and Australian grayling (Prototroctes maraena). For each species, we investigate the extent of genetic connectivity across a study region in south-eastern Australia (~700 km). We further determine the potential roles of contemporary ocean currents in shaping the patterns of genetic connectivity observed. Individuals across multiple rivers were sampled and >3000 single nucleotide polymorphisms were genotyped for each species. We found differences in genetic connectivity for the three species: common galaxias were highly connected, and Australian grayling and tupong exhibited patterns of isolation by distance. The degree of genetic connectivity for tupong and Australian grayling appeared unrelated to oceanic currents. This study indicates that the degree of connectivity for different diadromous species can vary greatly despite broadly similar life history strategies, highlighting the potential value of genetic tools for informing species-specific management plans.

了解连通性对于生物群的有效保护和管理至关重要。然而，直接测量连通性是具有挑战性的，它通常是根据围绕扩散潜力的假设来推断的，例如环境历史和物种生活史特征。遗传工具通常未得到充分利用，但可以可靠地推断连通性。在这里，我们表征和比较了三种澳大利亚鱼类的遗传连通性和遗传多样性：普通星河（Galaxias maculatus）、tupong（Pseudaphritis urvillii）和澳大利亚鳟鱼（Prototroctes maraena））。对于每个物种，我们调查了澳大利亚东南部（约 700 公里）研究区域的遗传连通性程度。我们进一步确定了当代洋流在塑造观察到的遗传连通性模式方面的潜在作用。对跨多条河流的个体进行采样，并对每个物种的 > 3000 个单核苷酸多态性进行基因分型。我们发现这三个物种的遗传连通性存在差异：常见的星系高度相连，澳大利亚的鳟鱼和 tupong 表现出按距离隔离的模式。tupong 和澳大利亚鳟的遗传连通程度似乎与洋流无关。这项研究表明，尽管生活史策略大体相似，但不同双栖物种的连接程度可能会有很大差异，