The Planet of Doctor Moreau:

 A planet with an unusual number of what appear to be Terran mutated animals & plants that have evolved intelligence.  Doctor Moreau was exposing life forms to radiation, mutating causing substances, vivisection experiments, cyber technology, genetic manipulation and much more. The planet is off the beaten space routes and the ships that went there where few.

 By the time the UPF became aware of the planet and what might had happened on it, whole cultures of sentient mutated animals with human type intelligence existed all of them aware that humans come from the stars and travel in space. 

There are several old films besides HG Well's based films and his book that have a mad scientist type in the middle of no where doing unthinkable experiments on animals, or people & animals. 

Or this planet could actually have been a colony ship's destination, but when they got there only the automated machines and animals survived, or very few humans... Dr. Moreau could be human or an android trying to fulfill his programing... I was just thinking could a location from which many animal/plant mutant races come from... some how a few escape the res so to speak. 

Might explain some hostility towards humans, if the uplifted races associate humans (even if human is really an android) with pain & suffering.

Or the Doctor is the guy who discovered a planet with a surprising number of Terran animals all mutated and ruins upon ruins of what appears to have once been a human colony... the doctor is leading a research team to figure out what happened, study the new life forms, and see if any humans survived... thus the Doctor is not the classic mad scientist, but he would be filling reports about strange life.