KOALA “BABY BONANZA” IN EAST GIPPSLAND; BUT ARE THEY “GENETIC” GOLD?

It was a koala baby bonanza when the World Wide Fund for Nature-Australia caught koalas in Gelantipy, East Gippsland to assist researchers working to ensure the species’ survival.

Of 20 koalas briefly captured, 14 were females with nine carrying joeys.

“It’s hard to imagine anything cuter than nine koala joeys but there was an important scientific reason behind why we were rounding up their parents. It’s possible they could be some of Victoria’s most important koalas,” said Dr Ashman, whose role is Threatened Species and Climate Adaptation Ecologist with WWF-Australia.

Tissue taken from the adults (the joeys were not sampled) was sent to the Koala Genome Survey, led by the University of Sydney.

The project is sequencing the complete set of genetic information from 450 koalas to build a genome map for the species across its range. Scientists are applying a level of genome sequencing unprecedented in animal research.

Most whole genome studies of wildlife only sequence the genome to a read depth of 5 to 7 times per sample; this means each location in the genome is sequenced 5 to 7 times which is not enough to eliminate errors.

However, the Koala Genome Survey is sequencing each location in the genome of every koala 30 to 60 times. The only other projects this thorough are human genome studies.

Such depth of analysis will enable scientists to identify which populations have important genetic variants – such as those for climate and disease resilience – that better equip koalas to adapt to a changing environment.

As reservoirs of crucial genes, those populations can be prioritised for protection.

In the future, through targeted translocations, vital genes could be introduced to populations with low genetic diversity – a move to strengthen the species.

The Koala Genome Survey was announced in February with more than $1 million in Federal and NSW government funding. Dr Carolyn Hogg, from the University of Sydney’s School of Life and Environmental Sciences, is the Program co-investigator.

“Since our Program started I’ve been encouraged and impressed by the way koala experts everywhere have reached out to see how they could help. The value of having a genome map of koala genetic diversity across its range is important to both the scientific community and all organisations working to save koalas,” Dr Hogg said.

WWF-Australia’s Regenerate Australia program Koalas Forever has the aim of doubling koala numbers on the east coast by 2050.

The genome survey could greatly assist this goal, prompting Dr Ashman to ask how WWF could assist the research. Dr Hogg highlighted a critical gap in samples from the East Gippsland region.

So in mid-October, Dr Ashman and Deakin University’s Dr Desley Whisson set out for Gelantipy to look for koalas, capturing 20 adults and 9 joeys in under a week.

Samples from the adults will unlock another chapter in the complicated story of southern koala populations (Victoria and South Australia).

Last century, hunting pushed southern koala populations to the brink of extinction. Much of Victoria and South Australia was re-populated from island populations established in the late 19^th and early 20^th century.

These island populations were often founded by just a few individuals creating a genetic bottleneck. Since most koalas in Victoria and South Australia are descendants of the island koalas they have very low genetic diversity.

The koalas from South Gippsland’s Strzelecki Ranges are an exception. They survived the hunting era and retain the diverse genes of Victoria’s original koalas.

“Soon we’ll know if the East Gippsland koalas can be traced back to the island koalas or if they’re another remnant population, a pocket of genetic diversity. That’s like finding a genetic pot of gold,” said Dr Ashman.

The Koala Genome Survey may also be able to find answers to the devastating overabundance issues that primarily occur in southern populations.

Koala densities can reach the point where food trees are stripped of all leaves, causing widespread tree death followed by koalas perishing from starvation.

“One theory is that southern koalas are so closely related they are less aggressive with each other and tolerate being near other koalas, enabling more breeding and higher densities. Northern populations don’t seem to typically accept such close proximity,” said Dr Ashman.

For the koala joeys of Gelantipy though, life is still pretty simple – just hang on to Mum and enjoy the ride.

About Regenerate Australia

Regenerate Australia is the largest and most innovative wildlife recovery and landscape regeneration program in Australia’s history. Launched by WWF-Australia in October 2020, the multi-year program will rehabilitate, repopulate and restore wildlife and habitats affected by the 2019-2020 bushfires, and help to future-proof Australia against the impacts of changing climate. Australia’s eastern koalas need support, you can add your support and help Regenerate Australia at www.wwf.org.au/regenerate-australia