Genetic fragmentation of mountain pygmy possum populations caused by the Victorian Great Alpine Road

The endangered mountain pygmy possum is restricted to three sub-alpine regions of Australia and is known as Australia’s only species that hibernates under a cover of snow.

Intuitively, some might therefore think that the most likely key threatening process for the endangered mountain pygmy possum is climate change; however, research has highlighted how human-induced habitat fragmentation and degradation can have a major impact on populations of the mountain pygmy possum, and is likely to be a more immediate threat than climate change.

With this in mind, cesar recently completed a project for the Department of Environment and Primary Industries (DEPI), Victoria that investigated the impacts of the Victorian Great Alpine Road on fragmenting the habitat of mountain pygmy possums in the Mt Hotham region, Victoria.

The Great Alpine Road is known to directly bisect two key populations of mountain pygmy possums at Mt Hotham; Mt Higginbotham east and Mt Little Higginbotham.

In the early 1980’s, research on the Mt Higginbotham east population showed that the Great Alpine Road caused social dysfunction of the population resulting in reduced matings, and in response to this, a rock scree corridor and culvert was constructed under the road, and the “Tunnel of Love” was born to reconnect habitat above and below the Great Alpine Road. However, no such tunnel was constructed at Mt Little Higginbotham.

cesar undertook genetic analyses of hair samples taken from individual mountain pygmy possums trapped in habitat above and below the Great Alpine Road at Mt Higginbotham east and Mt Little Higginbotham. Two populations within close proximity (Mt Higginbotham west and Mt Loch) were also sampled and included in genetic analyses for comparisons.

The Great Alpine Road was found to be a significant barrier to dispersal at Mt Little Higginbotham, whilst the “Tunnel of Love” was shown to reconnect habitat above a below the road at Mt Higginbotham east allowing dispersal and gene flow.

The study also revealed that populations of mountain pygmy possums at Mt Higginbotham, Mt Little Higginbotham and Mt Loch were highly genetically differentiated from each other, despite their close proximity (<3 km distance between all three).  

The major recommendations from the study were that habitat needs to be reconnected to re-establish a metapopulation in the Mt Hotham region. This should start with the reconnection of habitat above and below the Great Alpine Road at Mt Little Higginbotham.

Cover image: Photo by Andrew Weeks, Cesar Australia

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