Saw a post talking about the white Rhino only had 200 animals left but now there are so many more. But how is this done without serious inbreeding. Or is there something I’m missing?
Edit: yes, I know how sexy time works.
In: Biology
Serious inbreeding can be avoided with 200 animals. That’s enough to introduce enough genetic mixup without causing too much of a problem (if there were only 2 rhinos, and the whole population had to stem from that, you’d have potential problems).
There is something called the 50/500 rule made in 1980 by Australian geneticist Ian Franklin and American biologist Michael Soule. This rule suggests a minimum population of 50 in order to combat inbreeding, though a minimum of 500 to reduce genetic drift.
This is a bit of a generalization, and does vary species to species (species who have higher “litters” like mice and insects can tolerate lower populations than species with lower numbers (like large mammals or huge trees). So in the case of a rhino, 200 is probably enough to introduce enough genetic variability to avoid major inbreeding problems, but there may be some genetic drift, and if the population were to balloon back to normal wild levels, those Rhinos may be significantly genetically different from the wild Rhinos of old as a result of so many offspring coming from a small source gene pool.
EDIT: Wow, thanks for the silvers, responses, and support! I’m happy to have helped, in some small way, make the internet slightly more useful than a big porn box.
EDIT2: Now GOLD?! You flatter me, Reddit!
If i remember the paper correctly, you can re-breed from as few as ~30, though at that point it requires VERY carefully management and there will be some….unfortunate ones. Anything in the 3 figures is pretty manageable assuming the animals will breed in at least relative captivity, which isn’t guaranteed.
They did this with a type of gigantic vulture in California, they captured the remaining 23 BIRDS left and put them in a breeding program. There are now over 200 in captivity. The trick is to round those fuckers up and do the PewDiePie “now FRICK”
I actually just had this conversation with my professor last week because I was doing a presentation on de-extinction.
In this case, I believe the last male died, so they impregnated the female rhinos using his preserved semen.
The larger the population, the less need there is for inbreeding. It’s when there’s only a few members left that it’s an issue.
Not only can inbreeding be avoided, but inbreeding isn’t a genetic death sentence. It’s kind of a secret weapon for species coming back. Unless they get really unlucky, the carriers of defective genes die off without breeding, so after a few generations, the species has relatively broken free of any genetic defects caused by inbreeding.
They lack genetic diversity, and are more likely to have genetic diseases, but they still live on
Not only can inbreeding be avoided, but inbreeding isn’t a genetic death sentence. It’s kind of a secret weapon for species coming back. Unless they get really unlucky, the carriers of defective genes die off without breeding, so after a few generations, the species has relatively broken free of any genetic defects caused by inbreeding.
They lack genetic diversity, and are more likely to have genetic diseases, but they still live on
A very rigorous and extensive planned breeding program. Like others said, as long as they aren’t too genetically similar to start with, 200 is easily a big enough genetic pool to produce offspring without inbreeding effects. You just have to ensure, through relocation or captive breeding, that the various populations intermingle and continue diversifying. So you start by cataloging the existing animals and their genealogies as far as you can. Then you closely monitor the existing animals and ensure different lines are interbreeding. If a population becomes too isolated and begins trying to inbreed, then you move some viable adults from a different population into the stagnating one. It’s a lot of work.
I remember reading about how all giant squids, regardless of which ocean you find them in, have incredibly similar DNA. This could be a result of giant squids becoming nearly extinct at some point in time, and then later their population is restored, but it came from a limited gene pool, that is, the few survivors.
So when I want to join a religious cult living in isolation, gotta make sure they have at least 200 members.
At least in America, the AZA (Association of Zoos & Aquariums) maintains studbooks for each animal, one of the primary goals being to maintain genetic diversity. They can recommend transfers between zoos to make sure the gene pool stays diverse. I’m assuming this is only at AZA accredited zoos. [https://www.aza.org/studbooks](https://www.aza.org/studbooks)
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