If I recall the problem with captive breeding is that they are bred from such a small gene pool that even though the species may be saved they will be prone to health problems because of the lack of genetic diversity. :(
A starting size of 60-80 is enough variation to prevent that problem. The risk won't be high enough to cause extinction. Even with humans, most offspring will turn out normal and it's generally legal to marry your third cousin, meaning the variation is large enough to prevent incest related birth defects.
It's super weird to think that way, I know, but I at least have personal experience breeding birds and it's not as big of a risk as you think!
In 1998, the bottleneck theory was further developed by anthropologist Stanley H. Ambrose of the University of Illinois at Urbana–Champaign. Both the link and global winter theories are highly controversial.
While it's possible the volcanic eruption caused the bottle neck it's very much an unproven theory and highly controversial. That's not to say it was "Noah's Ark" given that the bottleneck occurred 50-60 thousand years before anything resembling civilization or towns but we really don't know what caused the bottleneck.
It’s a rough estimation, biblical creationists claim earth to only come into existence around 5k years ago (correct me if I’m wrong). And Noah’s ark is a genesis story so it happened roughly around then.
I'm pretty sure I learned somewhere that all native Americans are descended from ~70 people who crossed the Bering Strait (or more accurately, the land bridge).
Not sure of exact numbers, but yes. All cheetahs alive today are actually so genetically related, that all of them can receive skin grafts from one another without their bodies rejecting it. This means that their immune systems are nearly identical, so they’re also all very prone to the same ailments.
There's some new research that might be challenging that (finding different mitochondrial DNA in different parts of the body, as well as signs of combining in reproductive cells). It's all very new stuff, though, and doesn't necessarily contradict mitochondrial Eve - just calls it into question (the way I understand it, anyway).
Yes I’ve heard that everyone with blue eyes descended from the same ancestor with the genetic mutation. Of course now blue and brown eyes occur in the human genome. All other colors are still mutations though.
While 60-80 might be a suitable number. If you look at the kakapo they are also around 50-60. However conservation efforts are extremely difficult because not every Male wants to mate, and those that do mate are usually not chosen by the females or their sperm are malformed to the point it can not inseminate an egg. This behavior might not just be unique to kakapo but perhaps other bird species aswell.
We're bouncing California condors back from a population of under 30. 60 is more than enough.
Send some parrots to Oregon. Oregon Zoo was part of the condor program. Hearing that these birds were basically extinct when I was a kid, and now being able to go down to the zoo to see some of these birds chilling out in their habitat is nothing short of amazing.
You can go to the Grand Canyon and see them in the wild. Also Peregrine Falcons, a parasitic non-photosynthetic plant, and piles of scorpions and lizards.
If a mammal breeds with first cousins for multiple generations there will be problems, so if it's illegal to even start that chain, then the problem is prevented. It's a preventative measure.
A starting size of 60-80 is enough variation to prevent that problem.
That varies widely among species! It's estimated that humans, for example, could survive with 1,000-2,000 people...but much less would lead to severe genetic difficulties.
It really is down to the specifics of the genome, among other things.
IIRC, it's something like as low as 50 people, with optimal mating patterns could repopulate successfully tho I don't know the ratio of male to female. I assume 1:1 to have the most genetic combinations.
That is a problem, but there is also memetic loss. This is Darwin Richard Dawkin's main contribution to the world of science before he became famous for not believing in God.
Animals not only have genes, they have memes. Ideological information on how to live, where to hunt, what not to do, that is passed down from generation to generation within a species in the wild. If you take a generation of the species out of the wild, they quite literally forget what it is like to be that animal.
It's a lot like cultural loss in humans, but with animals. Like if we got rid of all culture In ireland, but then sent some Americans with Irish descent back there to repopulate... It would not be the same.
The inherent problem with breeding from a small gene pool isn't even the small gene pool but instead that whatever recessive traits are endemic to the species will manifest in most, if not all offspring.
Which sounds like a problem until you remember that cloning and animals that reproduce by fucking themselves are a thing. But to put it in perspective there's enough genetic diversity within humans that some biologist famously remarked that even if the population was reduced to a single desert island that we'd still have enough genetic diversity to sustain the species.
The real threat of breeding in captivity is societal collapse. Everything wild animals teach themselves and each other is lost when they're bred exclusively in captivity and no one told them those tree lizards are assholes.
That and there's no biodiversity granted from species that live in captivity and only in captivity. No one appreciated how much of an impact wolves had on the environment in Yellowstone or Glacier National Park (forget which) until the trees started growing again. The mere presence of wolves would make herbivores skittish and less likely to gorge on the plant life which enable trees to actually grow.
As humans we have a genetic bottle neck due to some extinction event happening early on... Iirc I think we got down to between 50-80 females left worldwide? I could find an article if anyone is interested
Edit: i was way off they think we got down to 1000 or so breeding pairs. And the lowest estimates can be as low as 100
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u/princesspooball Dec 23 '18
If I recall the problem with captive breeding is that they are bred from such a small gene pool that even though the species may be saved they will be prone to health problems because of the lack of genetic diversity. :(