Assessing genetic connectivity of eastern pygmy possums across a periurban landscape: insights for conservation planning

Urban fragmentation threatens biodiversity, particularly for species dependent on continuous habitat corridors. In periurban environments, fragmentation can disrupt gene flow and isolate wildlife populations, especially for arboreal mammals, but these effects are not well known for many species. We investigated the impacts of fragmentation on the eastern pygmy possum (Cercartetus nanus) a threatened small arboreal marsupial, using SNP-based genotyping of 119 individuals across eight habitat patches including across a major arterial road, in northern Sydney. Genetic diversity remained across the population, with low inbreeding and subtle population structure, suggesting ongoing gene flow. While some habitat patches showed minor genetic differentiation, the major arterial road was not a complete barrier to movement. Principal Coordinates Analysis, FST values, and Wilcoxon tests supported patch-level structuring shaped by landscape features rather than distance alone. Least-cost path modelling identified key corridors that will continue to support connectivity and inform the placement of wildlife crossing structures. Genetic methods can guide conservation actions in fragmented urban environments. Our findings suggest that with strategic planning, including the preservation of corridors and the implementation of targeted mitigation such as wildlife crossings, functional connectivity for sensitive species can be maintained, even in heavily modified landscapes.