Excluding Julian Bashir and the products of the human Eugenic Wars... do we ever encounter any species in Star Trek that have engaged in significant genetic self-modification or eugenics?
Basically are any other member species of the federation ever shown or said to have engaged in self genetic modification or is it only humans?
Are there any species or colonies inside or outside the Federation shown or implied to do so?
Memory-alpha has a section on eugenics.
In Plato's Stepchildren the aliens in that episode are the remnants of the population of the planet Sahndara "who were bred for their self-reliance, contemplation, and longevity".
The only other things it mentions about non-human eugenics are in relation to the Dominion, but that is the Founders acting on other races.
In the Affliction and Divergence two-parter, from Enterprise, the Klingons try to adapt human eugenics attempts to their own species, with nearly disastrous consequences (they accidentally created a plague and the cure resulted in Klingons losing their forehead ridges, explaining why they don't have them in TOS era but do elsewhen).
TNG' Unnatural Selection had the Federation itself returning to the genetic engineering well. The episode creates continuity problems as this exception to Federation law is never explained.
