Comparative landscape genetics of two co-occurring arboreal mammals in a highly developed Australian landscape

Background/Question/Methods

Landscape genetics links landscape ecology and molecular genetic information to quantify the influence of landscape variables on dispersal and gene flow within species. Landscape genetic patterns may be specific to the species, location, and the time at which individuals were sampled. Therefore comparative landscape genetic studies of co-occurring species within the same time period are useful for teasing apart differential use of landscape resources, and evaluating relative sensitivities of species to anthropogenic pressures. In southeast Queensland, Australia, two species of arboreal small mammals, the squirrel glider (Petaurus norfolcensis) and sugar glider (Petaurus breviceps) are at risk due to habitat fragmentation and rapid landscape change. We focus on how heterogeneity in at-site versus broad-scale landscape features differentially affects dispersal in these ecologically similar, yet genetically distinct species. Therefore, we ask: Do the relative costs of land cover variables to dispersal and the at-site drivers of landscape genetic patterns differ in each species? Finally, we address the implications of our findings for the management of gliders, and in relation to other co-occurring small mammals (e.g. the koala) in this highly urbanized landscape.

Results/Conclusions

Landscape features better explained glider genetic structure than a simple isolation by distance model. The relative resistances to dispersal of each land cover feature were similar between the two glider species. We found important differences between resistance due to roads and cleared areas compared to urban areas and forest cover. Forest projective cover appeared to act as a buffer for gene flow through developed areas. Important ‘at site’ drivers of connectivity included tree height, number of hollows and nearby habitat configuration, which differentially added to the strength of the landscape-genetic relationship. Thus, both squirrel and sugar gliders appear to be similarly sensitive to landscape heterogeneity in southeast Queensland. The results indicate that restoring structural habitat features in developed landscapes is important for maintaining connectivity. Our findings are of use for conservation planning and reserve design, and for identifying areas where increasing habitat connectivity may be most effective.