At least 6 threads here claiming selective breeding is really just evolution and it is a semantic issue. Would any experts please step up and clarify this?
Female African elephants are evolving without tusks due to ivory poaching
281–290 of 320 posts
Re: Female African elephants are evolving without tusks due to ivory poaching
#282Earlier quoted context omitted.
Assume that Bob knocks up both Alice and Eve. Alice has a son, Eve has a daughter. Alice's son knocks up Eve's daughter. Their kid will have two biological grandmothers, but only one biological grandfather. Apparently, historically, this type of thing was quite common and could heavily skew family trees towards the female side of things.
That skews the tree shape, but the odds of each baby are still ~50/50 so the overall population numbers should be stable.
Aussie was demonstrating how an individual could have more male ancestors than female ancestors. And his very simple example did in fact provide the 3:2 ratio that was previously mentioned.
Re: Female African elephants are evolving without tusks due to ivory poaching
#283Is this actually evolution or just selective breeding? By killing elephants with tusks the poachers are favoring elephants with the no-tusk gene. This isn't a lot different than killing a dog that bites sheep, which is how we bred herding dogs. Or a wolf that eats your baby, which is how we domesticated dogs. This trait already existed so it certainly wasn't "engineered due to mass poaching for ivory" as claimed.
Selective breeding is one form of evolution.
This is the correct differentiation. One possible selection mechanism of evolution is selective breeding. Others are predators, changes in the habitat etc.
Re: Female African elephants are evolving without tusks due to ivory poaching
#284Earlier quoted context omitted.
Assume that Bob knocks up both Alice and Eve. Alice has a son, Eve has a daughter. Alice's son knocks up Eve's daughter. Their kid will have two biological grandmothers, but only one biological grandfather. Apparently, historically, this type of thing was quite common and could heavily skew family trees towards the female side of things.
That skews the tree shape, but the odds of each baby are still ~50/50 so the overall population numbers should be stable.
The overall population is roughly 50:50, but men are more likely to be the "final node" in the family tree.
Let's adjust the example above slightly to include Bob's friend Darren, who who never got laid because he spent his whole life watching pornography and playing video games.
Even in this case, despite the 50:50 ratio of males and females both across society as a whole and within each generation, the child has more male ancestors.
This will be the case for any sufficiently large population where males have more variance in reproductive success than females, and people (of either sex) reproduce with others who have a shared ancestor (the closer the ancestor, the greater the effect the variance has on the ratio of male to female ancestors).
Re: Female African elephants are evolving without tusks due to ivory poaching
#285Earlier quoted context omitted.
That skews the tree shape, but the odds of each baby are still ~50/50 so the overall population numbers should be stable.
Aussie was demonstrating how an individual could have more male ancestors than female ancestors. And his very simple example did in fact provide the 3:2 ratio that was previously mentioned.
I think I misunderstood the proposition. Sorry.
Re: Female African elephants are evolving without tusks due to ivory poaching
#286In case anyone is wondering about the size of the effect, https://www.nationalgeographic.com/animals/article/wildlife-... has the numbers. Before the war, 2-4% of female elephants were tuskless. Now 32% of newly born ones are. So it's a significant change, but it's not like this property was coming out of nowhere. It started off about as common as humans having green eyes.
Downvoted for weird statements about green eyes. If there is a back story include it in your comment.
Re: Female African elephants are evolving without tusks due to ivory poaching
#287In case anyone is wondering about the size of the effect, https://www.nationalgeographic.com/animals/article/wildlife-... has the numbers. Before the war, 2-4% of female elephants were tuskless. Now 32% of newly born ones are. So it's a significant change, but it's not like this property was coming out of nowhere. It started off about as common as humans having green eyes.
Downvoted for weird statements about green eyes. If there is a back story include it in your comment.
What? They were just comparing the average rarity of the trait within a population. Literally googling "green eyes" would have given you the backstory: https://en.wikipedia.org/wiki/Eye_color#Green
Re: Female African elephants are evolving without tusks due to ivory poaching
#288A lot of elephants are killed for the ivory in their tusks
Some elephants are born without tusks and live much longer.
Natural mating between tuskless elephants will dramatically increase.
This will result in the trait being propagated rapidly.
Re: Female African elephants are evolving without tusks due to ivory poaching
#289Elephants are not "evolving" and it's not a "response" to poaching! Poachers killed elephants with tusks, and as a consequence elephants without tusks have a reproductive advantage. This is more like dog breeding than about nature fighting back.
Disagreed. This really is natural selection and not artificial selection. The poachers aren't selectively breeding for elephants without tusks. Quite the opposite. You are correct that it's a tautology - the elephants remaining are the ones without tusks - but that's exactly how natural selection works.
> The poachers aren't selectively breeding for elephants without tusks
Yes they are, that is exactly what they are doing.
There is nothing natural about it. It wouldn't happen if not for the poachers.
Re: Female African elephants are evolving without tusks due to ivory poaching
#290Earlier quoted context omitted.
Human behavior probably has the opposite effect in captive elephants. If a captive elephant is born without tusks then the Mahout is going to kill it rather than invest in rearing an animal that has much reduced utility and will not yield healthy offspring.
Elephants are not really bread in captivity.
They are bread in captivity. In Europe the breeding is organized by the European Endangered Species Programme.
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