“Without the theory of evolution, there is utterly no explanation of why the flora and fauna of each desert would be so different when the deserts themselves are so similar.”
Really? Seems like a pretty big leap of faith to assert this.
Not hardly.
If you take the biblical creation story as a scientific explanation of life on earth, there is utterly no explanation of why the flora and fauna of the Gobi would be so different than the flora and fauna of the western US deserts. In fact, there is no explanation of how the flora and fauna in either desert even exist, since they are not documented in the creation story and are not typical of the flora and fauna in the biblical lands. The creation story allows for no variability in species, and scammers like Ken Ham et al. who invent concepts like "adaptation" are neither scientific nor biblical with their scams.
If the creation story were a scientific description, the natural consequences would be that there would be little species variability across the world. All temperate deserts would have exactly the same plants and animals. Ditto for all temperate forests, all rainforests, all tundra, etc. And there would be no variability in humans, either. We'd all be the swarthy type of Caucasian that is common in the middle east, and everyone would look nearly identical. Since no one has ever observed anything of the sort, it stands to reason that the creation story is not, in fact, a scientific description.