TOXIC DIET: KOALA’S SURVIVAL

TOXIC DIET: KOALA’S SURVIVAL

Koala genes might reveal how they survive a toxic diet and might help us save them from chlamydia.

With their fuzzy gray bums and adorable faces, koalas are one of Australia’s most iconic mega fauna. A new paper published today in Nature Genetics documents the sequencing of the critter’s genome.

Koala’s genome took priority for a few reasons: it’s one of Australia’s most recognizable animals, its day-to-day life is only somewhat understood, and it’s endangered by threats that have yet to be fully understood or controlled.

Koalas are an iconic marsupial mammal, because they’re so recognizable, they’re a great species to use to educate people about things like genomic conservation.

Estimates of the current population of koalas vary from 100,000 to 600,000. Throughout their range, koalas vary in size and coloration, which at one time led them to be classified as three different species. But despite these phenotypic differences, she says, analysis of koala genes from across their range shows that they are one species after all.

Because of their wide distribution, they’re really complicated to manage from a conservation perspective. The koalas found in southern Australia have a high rate of inbreeding, but a large population.

If the genetic diversity in the south gets low enough and can’t be resolved in other ways, for instance, it might be possible to introduce genetic diversity using koalas from the north.

But the goals went beyond the relatively simple genetic analysis required to evaluate genetic diversity among the koala populations.

The fuzzy grey quadrupeds, which are unrelated to bears in spite of their common name, are unique among marsupials. Their closest modern relative is the wombat, but koalas and wombats diverged genetically millions of years ago.

Through taste and smell, the koala also has the apparent capacity to evaluate leaves on the basis of bitterness and water content; presumably they use these discriminatory powers to choose accordingly.

Though eucalyptus and its relatives are toxic to most animals, koalas have evolved to subsist primarily off its leaves—according to the Australian environmental agency’s website, koalas eat the equivalent of a small head of lettuce worth every day.

Besides habitat loss, dangerous people and dogs, and possible genetic bottlenecks, koalas face two other threats that are perhaps their most serious: chlamydia, which likely entered their population from domesticated sheep, and Koala retrovirus.

Long-term survival of the species depends on understanding the impacts of disease and management of genetic diversity, as well as the koala’s ability to source moisture and select suitable foraging trees.