Genetic viability

To be genetically viable, having a realistic chance of avoiding the problems of inbreeding, a population of animals requires a certain amount of genetic diversity, and consequently a certain minimum number of members. See effective population size. The minimum is normally somewhere in the region of a hundred unrelated individuals. Where a population has become extremely small in a population bottleneck, due for example to near-extinction of the species, it may have lost its genetic viability, and if numbers recover it will be through inbreeding, possibly leaving an unhealthy population. But in fact it provided a more diverse population thus limiting the amount of genetic disorder or repetition.