How the species are generated ?

I'm wondering about something. I imagine that planets and systems are procedurally generated (unless No Man's Sky has access to NASA data), but what about species? Are they generated via a genetic simulator based on the planet's conditions? I'm thinking in particular of larger animals on planets with low gravity, or things like that, with very diverse appearances via mutation simulations.

And if that's not already the case, wouldn't it be great if it were?