Beyond boundaries - genetic implications of urbanisation and isolation in eastern grey kangaroos (Macropus giganteus)

Understanding the long-term influences that urbanisation and associated habitat fragmentation can have on wildlife species is increasingly important for biodiversity conservation. Habitat fragmentation and subsequent isolation of previously connected populations can lead to smaller populations that are more likely to experience loss of genetic diversity. However, there is still a paucity of research directed at the genetic implications for species exposed to urbanisation. Eastern grey kangaroos ( Macropus giganteus ) are large macropodid marsupials that occur across a vast range on the eastern coast of Australia, inhabiting landscapes often subject to processes of habitat fragmentation and urbanisation. Using single nucleotide polymorphism (SNP) data obtained from scat and tissue samples, we compared genetic characteristics of urban and non-urban kangaroo populations across three study regions. We assessed the influence of habitat isolation characteristics on genetic diversity and relatedness of kangaroos at 18 study sites within these regions. On average, urban populations did not exhibit lower genetic diversity than those in less built-up areas ( p  > 0.05, Urban mean H _O = 0.196, Non-urban mean H _O = 0.188), but populations that were fully isolated by physical structures (i.e., roads, buildings and fences) had lower genetic diversity and higher rates of inbreeding. Significant regional differences were also found in the kangaroo population genetic characteristics. This study provides important insights into how attributes of complex and expanding urban landscapes can impact the genetics of large terrestrial mammals and has implications for guiding effective urban planning and management practices at an appropriate spatial scale.