Hanging in there: Koalas have low genetic diversity

Oct 23, 2012
A species relies on genetic diversity to survive and low diversity usually indicates that there has been inbreeding due to a decrease in population size. By looking at historic mitochondrial DNA from museum samples, new research published in BioMed Central’s open access journal BMC Genetics has found that koalas have had low genetic diversity for over 120 years. Credit: Dr. Eveline Dungl of the Tierpark Schönbrunn, Vienna, Austria

A species relies on genetic diversity to survive and low diversity usually indicates that there has been inbreeding due to a decrease in population size. By looking at historic mitochondrial DNA (mtDNA) from museum samples, new research published in BioMed Central's open access journal BMC Genetics has found that koalas (Phascolarctos cinereus) have had low genetic diversity for over 120 years.

The genetic diversity of koalas is known to be low in modern populations but historical reports suggest that koala populations have had a chequered past. When Europeans first noticed koalas in the late18th century they noted that numbers of this newly described species (originally called Lipurus cinereus) were very low due to Aboriginal hunting and they believed that the species would soon become extinct. Instead hunting declined allowing the koala to become a common animal by the mid 1800s.

At this point in time koala fur became fashionable and the international fur trade decimated the population once more. The was also hit by loss of their habitat to European settlement, and by devastating epidemic diseases such as Chlamydia.

Researchers from Germany, Denmark and the USA compared the of modern koalas and 14 from across the world (where the date of the specimen was known) to see how these changes in population sizes had affected koala genetic diversity. Despite the 14 historic koalas being from different places and time points, they each had only one of four different haplotypes (variations in the mtDNA hypervariable region) and all of these can be found in modern koalas.

Prof Alex Greenwood, from the Leibniz-Institute for Zoo and Wildlife Research, who led this study, commented, "We thought that, like other species such as the 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 must have happened a long time ago, perhaps during the late Pleistocene when the larger species of koala, P. stirtoni, became extinct."

Low may mean that the species is less able to survive changes to its environment such as global warming, or competing for habitat with humans. The low diversity may also be responsible for the widespread inability of the koala to resist diseases such as Chlamydia and the newly discovered koala retrovirus (KoRV).

Explore further: Female color perception affects evolution of male plumage in birds

add to favorites email to friend print save as pdf

Related Stories

Tracking koala disease: New findings from old DNA

Sep 26, 2012

(Phys.org)—DNA extracted from the skins of koalas displayed in European and North American museums shows that a retrovirus has been a problem for the animals for much longer than was thought, according ...

Research finds koalas are no dwarves

Dec 11, 2008

(PhysOrg.com) -- University of Queensland research has found one of Australia's iconic animals is not a shadow of its former self.

Koalas feel the heat

May 04, 2011

The Australian koala is vulnerable to climate change, with the iconic Australian marsupial's habitat likely to be restricted to the highly urbanised areas of eastern and southern Australia under a hotter and ...

Australia to protect most vulnerable koalas

Apr 30, 2012

Australia moved on Monday to protect its most vulnerable koalas, listing the much-loved furry tree-dwellers as a threatened species in parts of the country.

Fears for koalas as study reveals 'marked decline'

Sep 22, 2011

Australia's much-loved koala is under increasing threat and should be considered a vulnerable species, an official report found Thursday, with habitat loss seeing their numbers plunge.

Recommended for you

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.