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Evolutionary mechanisms

Discussion of everything related to the Theory of Evolution.

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Evolutionary mechanisms

Postby Forests » Wed Nov 07, 2012 3:14 pm

Hello,

I recently have been reading a lot of books on evolution and I have discovered many evolutionary mechanisms that are not usually discussed on internet forums. When we see talks on forums about evolution or other websites etc usually only natural selection, mutations or genetic drift is discussed as the mechanisms that cause evolution. But what if these mechanisms are not actually driving evolution? What if other mechanisms/processes are just as important or more important?

Here is a list of the mechanisms/processes I have found:


gene flow, genetic draft, genetic hitchhiking, horizontal gene transfer, endosymbiosis, symbiogenesis, paleopolyploidy (genome duplications), group selection, internal selection, kin selection, social selection, somatic Selection, autoevolution, molecular drive, niche construction, saltationism, self-organization, epigenetics, Semiotics, hybridization, natural genetic engineering, orthogenesis, nomogenesis, hopeful monsters, directed mutagenesis, morphogenetic fields, transposable element (jumping genes), hox genes, controlling elements, Phenotypic plasticity, Quantum evolution etc

Any opinions about any of these?
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Postby Luxorien » Fri Nov 09, 2012 12:51 am

I think it would be cool if these things got more press, because they are really interesting, but natural selection remains the primary engine of evolution.
If arguing with people on the internet helps me understand science, then I will do it. FOR THE CHILDREN.
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Re: Evolutionary mechanisms

Postby pathologicalliar » Sat Nov 10, 2012 11:04 am

Natural selection is probably one of the primary driving forces of evolution, but all the other mechanisms that you mentioned are also very important. it is difficult to say what is the most important driving force since i think that is situational.

correct me if i am wrong, but natural selection is more of a directed process where external conditions allow for random mutations in a a species genome to be selected for. the mutations might be random, but the selection is not.

some of the other mechanisms that you mentioned (genetic drift, hitchhiking) are random and may come to fixation in a population due to pure chance.
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Postby jinx25 » Sat Nov 10, 2012 11:49 am

People do not seem to realize there is no source of bulk amounts of NEW genetic information. Mutations you say? Hospitals are full of people with mutation (cancer, disease, sickness, death etc etc) Natural selection can only act on whats available and REDUCES genetic variation. Neodarwinian 'theory' (misnomer-once can only theorize about how something works AFTER it has been observed, it is an untestable conjecture/hypothesis) fulfills all the criteria of a pseudoscience AND THEN SOME.
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Postby RabbitPhilosopher » Fri Jun 21, 2013 6:22 pm

In my personal experience, I've seen about half of those discussed periodically in non-biology forums when it comes to debates about evolution. Some of those are not strictly mechanism of evolution but are biological processes (like semiotics, precisely biosemiotics). Natural selection is major mechanism of evolution and is non-random and others are random like mutations.
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Postby RabbitPhilosopher » Fri Jun 21, 2013 6:51 pm

As to the poster jinx25, you're factually wrong when you write that natural selection "REDUCES genetic variation." Please provide your source for your assertion and make sure it's from a peer reviewed science journal.

Yes, hospitals are full of people with mutations, heck we're human and we all have mutations. But I'm stunned that you seemed somewhat surprised to learn that hospitals have sick people in them. That's what hospitals are for! To treat sick people who have diseases like cancer! There are also people not in the hospitals, who are healthy and have beneficial mutations like CCR5-Δ32 that gives them immunity from the HIV virus ("Resistance to HIV-1 infection in caucasian individuals bearing mutant alleles of the CCR-5 chemokine receptor gene". Nature 382 (6593): 722–5.)

Your last sentence makes no sense.
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Postby RabbitPhilosopher » Sat Jun 22, 2013 5:06 pm

jinx25,

You have other factual errors in your post, you wrote "Hospitals are full of people with mutation (cancer, disease, sickness, death etc etc)".

"Death"is not a mutation and although some disease are cause by mutations the disease itself is not one. Your reasoning here is fallacious.
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Re:

Postby Cat » Sat Jun 22, 2013 5:36 pm

RabbitPhilosopher wrote:As to the poster jinx25, you're factually wrong when you write that natural selection "REDUCES genetic variation." Please provide your source for your assertion and make sure it's from a peer reviewed science journal.


You are wrong!
Natural selection is what kills off the slow rabbits (get eaten) and slow wolfs (die of hunger). Thus, it reduces the genetic variation of the species. You don’t need any articles on that.

Positive selection ascribed by some to natural selection has no proof. It’s based on hindsight and said to be “implied” by outcome. That is not science, but wishful thinking. In absence of humans (or other intelligent creature), positive selection does not exist.

P.S. Peer review of articles does not make them infallible. I find too many errors in them lately.
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Postby RabbitPhilosopher » Sat Jun 22, 2013 8:58 pm

Cat,

Again, thanks for pointing it out and explaining it to me. NS does tend to reduce variation (extinction for instance) and what I should have said is that it's still no argument against evolution.

Yes, peer review is not infallible (nature.com/nature/peerreview/debate) and they do at times contain errors even outright fraud (ncbi.nlm.nih.gov/pmc/articles/PMC1994041) but that's usually where the professionals publish their work and I'm not going to ask for sources from Kent Hovind or Answers in Genesis (although I admit I have a soft spot for some of Dr. Danny R. Faulkner writings).
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Re: Evolutionary mechanisms

Postby RabbitPhilosopher » Fri Jun 28, 2013 7:29 pm

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.
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Re: Evolutionary mechanisms

Postby Cat » Sun Jun 30, 2013 4:06 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.


No. Positive selection is selecting FOR a trait. Say a human taking a slow rabbits home (protecting it from wolves) and breading them...

To give you an example of unproven theory of positive selection:

Male birds of species X have bright plumage because those individuals that had it (ancestors) propagated more than those that did not have it.

There is no way to prove it since there are no males without bright plumage today.
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Re: Evolutionary mechanisms

Postby thoffnagle » Mon Jul 01, 2013 6:04 pm

Cat wrote:Male birds of species X have bright plumage because those individuals that had it (ancestors) propagated more than those that did not have it.

There is no way to prove it since there are no males without bright plumage today.


What?????? Sexual selection (one sex selecting the other based on traits) is one of the most powerful forces in evolution - if you can't attract a mate, you don't pass on your genes. And there are mountains of examples for it and observations of it. There are entire books on the subject - see Andersson M.B. 1994. Sexual selection. Princeton University Press, Princeton, NJ.
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