It sounds like they're evolving into separate species.
Indeed it's one definition of a species that it's a population that can mate within it's group. So if they can no longer breed with each other, are they same species or not?
Indeed it's one definition of a species that it's a population that can mate within it's group. So if they can no longer breed with each other, are they same species or not?
So it's not speciation, any more than sexes themselves are speciation.
This alone doesn't contradict the two-species theory. It could be that white-M + tan-F is species #1, and white-F + tan-M is species #2. Sure, it sounds weird, but not nearly as weird as the idea of 4 sexes, IMO.
> (And the offspring are about half white-striped and half tan-striped.)
Now, this is the important part. As I understand it, the offspring of "species #1" could be "species #2" or the other way round. This indicates that #1 and #2 are the same species after all.