It turns out there's a special word for this Darwinian sense of "evolution": Hovje'voH.

Maltz said that is a rather technical term; he's also heard mutchoH, which clearly comes from mut "species" and choH "change." He didn't know what the etymology of Hovje'voH was.

You're right that Klingons don't like to talk about "primitive Klingons," but they are quite aware of evolution, in particular how Human, Klingon, Cardassian, and other species all started from the same DNA that had been scattered on planets in the Alpha and Beta Quadrants and then evolved in different places into different (but ultimately related) species (ST:TNG "The Chase").