Genetic mutation rates

How much do the mutation rates between different species vary?

I ask because a friend recently told me that apple trees genetically mutate a lot more than other trees, which he claims makes them more adaptable to climate change. It sounds plausible to me, but I’m not sure how significantly the mutation rate difference can be amongst species.

Thanks for any help.

What’s the matter, are all the evolution geeks hanging out in Great Debates?