Success of mountain pygmy possum genetic rescue

The home of the endangered mountain pygmy possum, Burramys parvus, is limited to the alpine regions of Australia – a very small range indeed!

Sadly, one population at Mt. Buller is particularly threatened, having experienced a decline similar to a population collapse, caused by feral predators and habitat destruction.

By 2005 there were less than 20 mountain pygmy possums known to be present in the population at Mt. Buller.

What’s more, with fragmentation from other mountain pygmy possum populations in the alpine region over 20,000 years ago, the genetic diversity of this population had reached a very low ebb. A diverse gene pool is crucial for population adaptation and resilience in the face of adverse conditions, such as changing habitats, and disease.

Genetic translocations to the rescue

To help bring back this dwindling mountain pygmy possum population, scientists at cesar, together with the Burramys rescue team*, carried out a conservation approach called ‘genetic rescue’. Genetic rescue is a strategy that has the potential to increase gene flow in a population resulting in greater genetic diversity, higher adaptability, and an overall increase in population size.

This ambitious genetic rescue program involved translocating 6 healthy and genetically diverse pygmy possum males from a central alpine population to the population at Mt. Buller in Spring 2011. The changes in the Mt. Buller population sizes were then assessed by annual live trappings (Elliot type A live capture traps).

Were the translocations a success?

Promisingly, the genetic diversity of mountain pygmy possum has increased along with population size as a result of these introductions.

Trapping data collected in the years after the translocations found that hybrid males were larger than resident males and hybrid females had 4 pouch young compared to less in resident females. Furthermore, overall fitness and longevity in hybrids was greater than it was in non-hybrids.

Since 2011, the population has gone through rapid growth and is now larger than when the population was first discovered in 1996

An environmental improvement programme that had also been implemented in the Mt. Buller region from 2008 to 2011, involving habitat restoration, predator control and environmental protection, and likely lead to a small initial increase in population size at Mt. Buller prior to 2011.

Genetic rescue could save other threatened species

Our work has shown that applying genetic rescue methodology further increased the population of mountain pygmy possum in the Mt. Buller region after threatening processes such as habitat loss, predation and human activity had been mitigated.

A large number of other species could potentially benefit from genetic rescue because many threatened species exist as small isolated populations lacking genetic variation alongside larger populations with higher levels of genetic variation.


*cesar researchers, Dr Andrew Weeks and Anthony van Rooyen, and collaborators from the University of Melbourne, La Trobe University, The University of NSW and Mt Buller Mt Stirling Resort Management

Cover image: Photo by Andrew Weeks, Cesar Australia

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