There are different species of Koala in Australia and they have adapted to live on only about 40 (of 600) different kinds of eucalyptus. But there are no koalas native to Tasmania where there are eucalyptus (though perhaps not one of the 40). Why didn't koalas evolve so they could survive on Tasmania?

no way we can know for sure but the following may be relevant:

1. the eucalyptus trees in Tasmania may not be optimal for Koala survival
2. there will be many other local environmental factors other than eucalyptus that may preclude Koala survival in Tasmania
3. Tasmania is well over 400 miles from southern Australia and presumably the 2 landmasses split before Koalas evolved. They may never have made it to Tasmania in significant numbers.

I would favour (1) and (2) - as far as I am aware there are also 'no native' koalas in the NT or WA.

P.S. The wikipedia entry on Koalas states that there is fossil evidence for koalas in WA, but that 'they were likely driven to extinction in these areas by environmental changes and hunting by indigenous Australians'.

Last edited by Steve Lolait (12th Jan 2016 10:15:25)