Conservation genetics of the Brolga (Antigone rubicunda) across eastern Australia reveals genetic structure and potential loss of adaptive capacity

Abstract Globally, urban expansion and agriculture have driven widespread wetland degradation and loss. The Brolga ( Antigone rubicunda ), a wetland-dependent crane species distributed across northern and eastern Australia, is threatened in south-eastern states. In Victoria, census estimates remain below 1,000, and the species is state-listed as ‘Endangered’ due to anthropogenic disturbance, particularly wetland drainage. Here, we sourced DNA from naturally discarded feathers and feathers collected from captured birds, and genotyped 125 Brolgas at 7,712 single nucleotide polymorphisms to examine broad-scale genetic structure and dispersal patterns, and to estimate contemporary effective population sizes. We identified two genetic clusters: a northern cluster (including northern New South Wales) and a southern cluster (represented by individuals from Victoria). No evidence of sex-biased dispersal was observed, and higher genetic similarity among individuals sampled at the same locality suggests some site fidelity. Both clusters fall below the recommended minimum effective population size of 1,000, increasing the risk of losing genetic diversity and adaptive potential in the long term. Modelling the effects of various management strategies on genetic variation indicated that the southern cluster may be more vulnerable to genetic erosion, with losses up to 15% under severe bottlenecks, compared with ≈ 5% in the northern cluster. Our results highlight the importance of effective habitat management for both populations, particularly in Victoria where risk is highest, and emphasise the need for proactive conservation to ensure long-term survival.