Limited Dispersal and Fragmentation-Induced Genomic Erosion in Southern Greater Gliders (Petauroides volans)

Forest fragmentation and isolation are critical threats to arboreal marsupials. The endangered southern greater glider (Petauroides volans) is vulnerable to the effects of forest loss and fragmentation, yet the species' natural dispersal patterns and genetic outcomes under different habitat contexts remain poorly understood. This study characterises population genomic patterns in southern greater gliders from continuous and isolated forests in southeastern New South Wales, Australia. Using genome-wide single nucleotide polymorphisms, we genotyped southern greater gliders (n = 70) sampled from continuous forests at Mount Lindsey and Tallaganda, and an isolated forest at Seven Mile Beach National Park. Genomic diversity was significantly higher in the continuous forests compared to the isolated forest, which exhibited elevated relatedness and a low effective population size. Fine-scale spatial genetic structure (0-250 m) was detected across all sites, consistent with limited dispersal. In the continuous forests, inferred parent-offspring pairs were separated by no more than 67 m, suggesting philopatry. In the isolated forest, parent-offspring separation was either no more than 75 m or > 700 m, suggesting both philopatric and dispersing offspring. Co-denning occurred between related and unrelated conspecifics, including a breeding pair with their adult offspring, indicating sociality beyond maternal and mating associations alone. Our findings indicate that dispersal is typically limited in southern greater gliders and isolated populations are vulnerable to genomic erosion. Conservation strategies must prioritise maintaining forest connectivity to mitigate the genomic consequences of isolation and should consider the species' limited dispersal when planning management actions.