I've recently conquered a bunch of planets my guys can live on alright, only problem is its full of the unlucky conquered pops. Nonchalantly, I opened the new species tab and ordered these 'undesirables' to be taken care of (god, this game is sick). Then a thought crossed my mind. What if I wanted to keep some of them around to serve my soon-to-arrive colonists? Is there a way to only thin out their population to make room for my own species? It seems its do it or don't at the moment, killing all pops of a given species or none. Can somebody enlighten me?