Elephants without tusks are a response to the selective pressure of poaching
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Re: Elephants without tusks are a response to the selective pressure of poaching
#2>While virtually no male elephants are tuskless (they need tusks to fight), about 2 percent of female elephants are naturally tuskless. Among female elephants in Gorongosa who were adults during the civil war, however, half are tuskless — the others were simply killed. But tusklessness is an inheritable trait. That means that, even though poaching levels have fallen, a third of Gorongos’s young female population is tuskless today.
I think the correct term is survivor bias.
Update re downvotes: The title literally says "Elephants without tusks are a response to the selective pressure of poaching".
The body text says "2% of female elephants are naturally tuskless" (emphasis mine).
So "Elephants without tusks" per se are natural.
"(Massive) Increase in % of tuskless offspring as a result of selective killing of tuskfull adults (given that tusklessness is an inheritable trait)" seems like a more accurate, yet obvious (almost tautologically so) observation. It seems to be true when the trait is inheritable and strongly discriminated against - the children of the survivors look more like the survivors than those who were killed because they (the killed) were different. You don't say!
Re: Elephants without tusks are a response to the selective pressure of poaching
#3>While virtually no male elephants are tuskless (they need tusks to fight), about 2 percent of female elephants are naturally tuskless. Among female elephants in Gorongosa who were adults during the civil war, however, half are tuskless — the others were simply killed. But tusklessness is an inheritable trait. That means that, even though poaching levels have fallen, a third of Gorongos’s young female population is t…
I think your correction is mistaken. Survivor bias is a logical error [1]. This sounds like natural selection with human activity acting as a selection factor.
"[Survivor Bias] is the logical error of concentrating on the people or things that "survived" some process and inadvertently overlooking those that did not because of their lack of visibility.
Re: Elephants without tusks are a response to the selective pressure of poaching
#4>While virtually no male elephants are tuskless (they need tusks to fight), about 2 percent of female elephants are naturally tuskless. Among female elephants in Gorongosa who were adults during the civil war, however, half are tuskless — the others were simply killed. But tusklessness is an inheritable trait. That means that, even though poaching levels have fallen, a third of Gorongos’s young female population is t…
Evolution is the ultimate survivor bias :-)
Re: Elephants without tusks are a response to the selective pressure of poaching
#5This is the saddest example of "natural" selection I've heard of.
Re: Elephants without tusks are a response to the selective pressure of poaching
#6>While virtually no male elephants are tuskless (they need tusks to fight), about 2 percent of female elephants are naturally tuskless. Among female elephants in Gorongosa who were adults during the civil war, however, half are tuskless — the others were simply killed. But tusklessness is an inheritable trait. That means that, even though poaching levels have fallen, a third of Gorongos’s young female population is t…
http://www.nature.com/scitable/definition/evolution-78
>Microevolution reflects changes in DNA sequences and allele frequencies within a species over time.
Allele frequencies changed from ~2% to ~33%. Mutations are not necessary for the process, unless the allele is at 0% frequency to begin with.
Re: Elephants without tusks are a response to the selective pressure of poaching
#7>While virtually no male elephants are tuskless (they need tusks to fight), about 2 percent of female elephants are naturally tuskless. Among female elephants in Gorongosa who were adults during the civil war, however, half are tuskless — the others were simply killed. But tusklessness is an inheritable trait. That means that, even though poaching levels have fallen, a third of Gorongos’s young female population is t…
Naturally meaning born without.
Re: Elephants without tusks are a response to the selective pressure of poaching
#8Do poachers have an incentive to kill tuskless elephants too, then, so they don't become more dominant than tusked ones?
Re: Elephants without tusks are a response to the selective pressure of poaching
#9>While virtually no male elephants are tuskless (they need tusks to fight), about 2 percent of female elephants are naturally tuskless. Among female elephants in Gorongosa who were adults during the civil war, however, half are tuskless — the others were simply killed. But tusklessness is an inheritable trait. That means that, even though poaching levels have fallen, a third of Gorongos’s young female population is t…
Naturally meaning born without.
Yes.
Re: Elephants without tusks are a response to the selective pressure of poaching
#10There's an interesting comment about a similar thing happening with rattle snakes. It seems they evolve into silent snakes to better avoid human predators: http://www.abc15.com/news/region-phoenix-metro/central-phoen...