The Commonwealth has rejected calls to protect a tiny Victorian population of koalas, which some experts believe could be essential to the species’ survival.
Thought to have been driven to extinction across the state by hunting and land clearing, the Strzelecki koalas were rediscovered in the 1990s, surviving in fragmented habitat across South Gippsland.
The Commonwealth rejected the submission to list Strzelecki koalas as threatened in October, saying more work was required to confirm it was “demographically separate from adjacent populations” — a key component required for listing.
It said data available about the animals is “insufficient” and further research is required to estimate population size and trends.
Why are the Strzelecki koalas important?
Environmentalists are concerned Strzelecki koalas are being impacted by the logging of the plantations where they live, and the clearing of land for agriculture.
They would like to see the population receive similar protections to NSW, Queensland and ACT koalas which are listed as endangered under the Environment Protection and Biodiversity Conservation (EPBC) Act.
While koalas are thought to be abundant in the state, all animals except for the Strzelecki population are more susceptible to health conditions stemming from a genetic bottleneck during a near extinction event.
That means they are also likely to be worse affected by climate change. They are prone to kidney disease which can occur after bushfires or drought dries out eucalyptus leaves, the koala’s only food source.
Why is there insufficient data about Strzelecki koalas?
Strzelecki koalas were nominated for listing by Friends of the Earth Victoria. Spokesperson Anthony Amis said he is “extremely disappointed” but "not surprised" by the outcome as there have been few publications on the animals.
He puts much of the blame for the rejection on the shoulders of successive Victoria governments, which he argues have shown “little interest” in understanding population size or research.
The number of Strzelecki koalas remaining is hard to establish, and Victoria’s department of environment (DELWP) did not respond to a direct question from Yahoo News Australia about population size.
It did indicate its draft Victorian Koala Management Strategy will set out clear actions to conduct a survey of the animals.
“The Victorian Government is taking action to ensure the long-term protection and survival of Victoria’s koalas and their habitat, and will release a new management strategy shortly,” it said in a statement.
“The new Victorian Koala Management Strategy will ensure Victoria’s koala populations and habitat are secure, healthy and sustainable in the long-term.”
What the experts say about Strzelecki koalas
Understanding the significance of Strzelecki koalas probably requires a basic understanding of genetics.
Research led by Tristan Lee in 2011 focused on the animals' microsatellites which are tracts of repetitive DNA that have high mutation rates and lead to more diversity.
He found Strzelecki koalas are “genetically distinct from other koala populations examined”.
A further study by Dr Faye Wedrowicz in 2018, which used both microsatellite genotype and mitochondrial DNA sequence data, concluded was greater genetic diversity in South Gippsland koalas than in other ranges.
Dr Carolyn Hogg from the University of Sydney is examining the genomes of 20 of the region’s koalas as part of the Commonwealth-funded Koala Genome Survey.
Rather than using microsatellites which cover about 10 locations in the genome, her whole genome analysis covers about 50 million.
“All Victorian koalas show different genetic diversity to Queensland but share genetics with southern NSW populations,” she said.
“Koalas from South Gippsland represent the highest genetic diversity of all Victorian populations but there is no indication they are significantly different from any other Victorian koala populations.
“That is, no single Victorian population has unique genetics.”
She said further analysis of haplotypes, the set of DNA variants along a chromosome which are often inherited by a single parent, could identify further differences over the coming months.
Dr Stephen Phillips from ecological consultancy Biolink has developed expertise in the Strzelecki population.
He has been involved in research that maps where the animals likely originated, focusing on a range between Jumbuk, Churchill and Morwell.
The team have recorded Strzelecki genes within a radius of 100 kilometres of this range, noting they get weaker the further animals are from “ground zero”.
"I'd like to see the Strzeleckis recognised for what they are, and their potential role for genetic recovery of koalas in Victoria," he said.
"It would be lovely for the [state] government to fully recognise the uniqueness and special nature of this population, and to work as hard as they can to ensure its long-term survival."
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