Evolutionary mechanisms

Discussion of everything related to the Theory of Evolution.

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Re: Evolutionary mechanisms

Post by thoffnagle » Mon Jul 01, 2013 6:12 pm

RabbitPhilosopher wrote:Since natural selection tends to reduce variation does it also hold true at the ecological level in fauna flora interactions? Using cat's example of slow rabbits getting eaten and reducing variation of this species, will this help increase variation of certain plants since there will no longer be certain animals (rabbits) around to eat them? Is this a case of unproven positive selection and I'm simply not understanding? Any help I could get would this would be greatly appreciated.

Yes, natural selection reduces variation by weeding out maladaptive genes. Mutations of various kinds provide new genes and alleles for natural selection to act on.

A good example of what you are asking about happened in Yellowstone National Park. When wolves were removed (early 1900s), moose, elk and deer were able to be lazy and lounge in the shade of aspen groves where they ate all of the young aspens. This resulted in very few (none, in some places) new aspens and the groves were starting to die off. However, when wolves were reintroduced, they started hanging out in the shade and the moose, deer and elk left to avoid being eaten. This allowed new aspens to grow. If the wolves hadn't been reintroduced, many aspen groves would have disappeared.

I remember reading a similar (but more complicated) story about orcas, seals, sea lions, fish, sea otters, kelp and sea urchins one time.....I should look that up....
"Nothing in biology makes sense except in the light of evolution."
Theodosius Dobzhansky
"Most people who hate the idea of evolution do so because if it was working properly, they'd be dead."

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Post by RabbitPhilosopher » Sat Jul 20, 2013 10:11 pm

That was a good example, thank you thoffnagle.

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