The same argument could apply when you take plants or animals from one continent to another when those continents haven't been connected for tens of millions of years.

Yet somehow camels or kangaroos seem to have no trouble living in each others environments.

In fact, you see a bit of the reverse - Banana skin rapidly decomposes in tropical forests where bananas grow, but take one to frigid Norway and drop a banana skin in a forest and you'll still be able to find it in 5 years, while local stuff is decomposing around it.

The part of the banana skin looks like a very nice experiment if you have a webacam and five years available.