If you have a low population of an endangered species, how do you get the numbers up without inbreeding or ‘diluting’ the original species?

Question

I’m talking the likely less than 50 individuals critically endangered, I’d imagine in 50-100 groups there’s possibly enough separate family groups to avoid inter-breeding, it’s just a matter of keeping them safe and healthy.

Would breeding with another member of the same family group* potentially end up changing the original species further down the line, or would that not matter as you got more members of the original able to breed with each other? (So you’d have an offspring of original parents, mate with a hybrid offspring, their offspring being closer to original than doner?)

I thought of this again last night seeing the Sumatran rhino, which is pretty distinct from the other rhinos.

Edit: realised I may have worded a part wrongly. *genus is what I meant not biologically related family group. Like a Bengal Tiger with a Siberian Tiger. Genetically very similar but still distinct.

In: Biology

Answer 1

A quote about the topic: [The study examined 95 mammal species, 20 percent of which are endangered and 10 of which are on what the authors call “the tipping point” where they could be at the “point of no return.” That tipping point, according to the authors, is a species with a population below 5,000 individuals.](https://blogs.scientificamerican.com/extinction-countdown/australian-mathematicians-say-some-endangered-species-not-worth-saving/) This means that normally, it’s extremely hard to bring populations below 5,000 back to safe numbers.

If the breeding pool is as low as fifty, it’s nearly impossible to raise it back up. A certain percentage of the animals will be infertile or die before adulthood. Then, you have to consider why the population has gotten so low. If the species is going extinct because of habitat loss, that will still limit the amount of animals that can survive.

In regard to your second question, evolution is constant. In this case, genetic drift is possible. This means that depending on the characteristics of the survivors, future generations may be different. Say you had 100 butterflies; 20% red, blue, green, yellow, and purple. Fifty randomly died, leaving 50% red, 30% blue, 28% green, 2% yellow, and 0% purple. About half of their kids will be red, and none will be purple. The species will have “accidentally” evolved to not have purple anymore. If this doesn’t happen, evolution will still happen, but it’ll take longer to notice.