Zoos are the last resort for some species. Though their capacity is limited, zoos are an opportunity to aid in preservation of some of the endangered species. Zoos can assist by giving priority for endangered species over abundant species and by applying breeding programs for endangered species. Again the key is genetic diversity. It is necessary to adapt back to environment in the wild.
The last two centuries genetic diversity decreased within most if not all domestic breeds. This resulted in a high incidence of breeds specific genetic diseases. What to do if you want your breed to be healthy?
Mean kinship is widely accepted as a conservation method within zoos.