Scientists studying koalas have discovered that the species has had low genetic diversity for over 120 years. The level of genetic diversity a species has influences their ability to survive, with higher genetic diversity giving the species greater chance of surviving environmental changes and other challenges. Low genetic diversity can put a species at higher risk of extinction and is often associated with a declining population.
Professor Alex Greenwood, from the Leibniz-Institute for Zoo and Wildlife Research, who led the study which examined mitochondrial DNA from museum specimens of koalas to establish historical data on genetic diversity. According to Professor Greenwood, their findings ran counter to what they expected. "We thought that, like other species such as the grey wolf where the population has recently declined, there should be greater diversity in museum samples than modern specimens. We found this not to be true. The event which reduced the genetic diversity of koalas must have happened a long time ago, perhaps during the late Pleistocene when the larger species of koala, P. stirtoni, became extinct."
The low genetic diversity in living koalas makes them more sensitive to changes such as global warming, disease resistance and habitat destruction.