Superspecies: species that are very closely related but do not interbreed.
And here are three bonus words. Free:
“Sympatric,” “Subspecies,” and “Allopatric.”
“Sympatric” species like the Western and Eastern meadowlark don’t interbreed even though they are very similar and live in overlapping areas.
Why don't they? Well sometimes they don’t like each other. Sometimes it’s just inconvenient. And sometimes they simply can’t figure out how. (Superspecies status doesn’t necessarily mean super-smart-species.)
Eastern_Meadowlark
Now for “Subspecies.” (Obviously a notch down the pecking order.) Let’s take for example the Northern Mallard and Mexican Duck which commonly paddle around in the same pond, so to speak. Frequent interbreeding produces hybrids and “waters down” the species. In this case the Mexican Duck's. And...unfortunately it gets demoted to subspecies status. (I say unfortunate, but please don’t feel sorry for the birds. They don’t care. It’s birders who are the real victims. We don’t get to count them on our life lists.)
And finally “Allopatric?” The Oak Titmouse lives in the west. The Tufted in the east. Both are superspecies. I know they don’t look especially super. But they fit the definition: they don’t interbreed because they’re separated by geography. So it never comes up.
Oak Titmouse
Now a word, if I may, about the name: “titmouse.” Who came up with that? It seems unmeet somehow. I know it goes way, way back. Like eight centuries. (But who’s counting?). For a science that swaps species names around yearly like a Chinese puzzle, that’s a long time. Couldn’t they come up with something more, well…modern?
It’s from the Middle English word “tit” meaning small. And Mose which came from Old Norse meising meaning something like “puny weakling.”
Now I’m aware nobody wants to talk about the elephant in the room here, but I’m going to: frankIy I find the name inappropriate.
After all, we’re talking superspecies. Superspecies.
Wouldn’t Mighty Mose be more fitting?