What are the conservation implications of the koala genome and what role does their evolution play?
New information from the Koala Genome Project is critical in understanding and communicating the threats that modern populations face.
We use a technique that estimates demographic history over thousands of generations from genome sequence. Looking back >100,000 years, koalas were at their peak population size of 50,000 – 86,000 animals. At around 30-40,000 years ago the population underwent a rapid decrease, then stabilised to about 10% of their previous numbers. This rapid decline coincided with the time that other Australian species, especially the megafauna, underwent widespread extinction, pointing to a significant climatic or habitat change.
Those stable population numbers were again dramatically reduced by European settlement around 200 years ago, when millions of koalas were hunted for their skins, resulting in extinctions and severe bottlenecking in southern Australia. This is the koala population we are now faced with conserving in the current day.
One of the biggest modern threats to koala survival is land clearing. This has led to loss of habitat, and loss of connectivity between habitats. One of the long-lasting outcomes has been reduced genetic diversity and possibly inbreeding. This is complicated by the wide geographic distribution of koalas throughout Australia, covering many bio-regions and four Australian states.
Good news has come from our populations studies using new genome markers. Using genome linked markers, we show, for the first time, that NSW and Queensland populations retain significant levels of genetic diversity and still show long term connectivity across regions. Ensuring this genetic diversity is conserved, is the key to the long term survival of this species, and genetic monitoring must accompany conservation measures to protect habitat, and reduce dog attacks, vehicle strikes and disease.
This work represents the new generation of science based conservation policy as it has been integrated as an important pillar into the NSW Koala Strategy 2018. Sequencing the koala genome represents a paradigm shift for Koala research and conservation efforts.
Dr Rebecca Johnson , Director, Australian Museum Research Institute