Genomic Vulnerability of a Threatened Possum in a Biodiversity and Climate Change Hotspot.

Spatial variation in the magnitude and pace of climate change impacts means some species will be more affected than others. This includes those occurring within global biodiversity hotspots, regions with exceptional concentrations of endemic species that have often been shaped by long-term climatic stability. Disproportionate levels of human-induced pressure in these areas are threatening much of the biodiversity values that make these biodiversity hotspots exceptional. Southwest Western Australia is a highly fragmented temperate biodiversity hotspot experiencing rapid climate change and supporting many species of threatened mammals. One Critically Endangered arboreal folivore, the western ringtail possum (ngwayir; Pseudocheirus occidentalis), has contracted to ~10% of its range since European colonisation, has a history of translocation failure, and is being impacted by increasing aridity. Here, we used 9746 SNPs from 411 ngwayir distributed across southwestern Australia to assess climate adaptation and genomic vulnerability to climate change under three climate change scenarios and four time periods. We also compared the degree of adaptive mismatch imposed by a successful and a failed translocation to consider its contribution to translocation success. We found that ngwayir had low genetic diversity and high genomic vulnerability in the northern edge of their range, where threats such as urbanisation exert substantial pressure on populations. Genomic maladaptation did not appear to drive differences in translocation success, while genomic vulnerability scores identified areas most suitable for future translocations in the central southern portion of the species range. Collectively, our analyses reinforce the importance of urbanised areas for the conservation of ngwayir, and we suggest these areas are prioritised for adaptive management initiatives.