Andy.. let's not make this a case by case thread...
Sure odd things can be found in nature, doesn't mean it's natural..
These crosses are accident, they aren't there for a purpose.
BUT ! If they are, to serve a purpose (i.e. hybrid iguana) what so ever well that's another story. Maybe she crossed so that a specie can survive on this island because of some disturbance in their habitat.
But we can't really speculate nor discuss about this at this time.. maybe in a couple of million years.