Cat-fox species?

[Drewbot]

I'm decidedly biased toward lumper. Modern hyper-splitting species concepts have subsumed the population as a level of biological complexity.

This has led to such silly discussions as the folks oohing and aaahhing over the complicated situation of Nelson's and Sharp-tailed Sparrows co-occurring in salt marshes on Atlantic Coast of New England and the Maritimes. Evidently, we now know that there is quite a bit of hybridization – including multiple types of backcrosses – between these very similar species. I'm like, "Yeah, no clue, Sherlock. That's because they're the same damn species."

Ditto Corsican "cat-foxes". They're cats, bruh. It's a cool population of cats if they've got some unique pelage and/or dentition. But they're . . . cats.

I agree with the lumping. However, I do think natural barriers such as oceans or mountain ranges, or large rivers can be a huge influence on how we differentiate a species.

Your ST Sparrows are easily able to breed because they are in the same location, if one was on each side of the Himalayan mountains, then they would be different species.

 

[The Shrike]

I agree with the lumping. However, I do think natural barriers such as oceans or mountain ranges, or large rivers can be a huge influence on how we differentiate a species. . . . . Sparrows . . . on each side of the Himalayan mountains, then they would be different species.

Right. Something that actually presents a barrier to gene flow makes sense, but I'd modify your would to a could: Just because there's a physical barrier doesn't mean gene flow is all that restricted. Often the infusion of a single individual every few generations is all that it takes to dampen whatever genetic drift might have occurred in the meantime.

Cats on Corsica might have been reproductively isolated for what seems like a long time to us, but even a few thousand years is a relative eye-blink. There's – or there should be – lots of room for modification resulting from isolation and genetic drift that wouldn't/shouldn't demarcate a different species.