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Questions about phenotypic plasticity

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Questions about phenotypic plasticity

Postby tekla » Sun Dec 02, 2012 11:38 am

Hi all!

Hope you can help me with this question I have, and I hope I can get the question clear enough since english isn't my language.

I wonder if a phenotypic plasticity trait can lead to a change in the genetic material? For example, if a species is very plastic so it can persist a change in the environment due to that, can that change/trait become "fixed" due to evolutionary selection? I was thinking that if a certain phenotypic trait that has become more common due to climate change, that would also lead to a new genetic adaptation since the other traits that has less fitness would die off, but than someone told me that phenotypic traits can never lead to new evolutionary changes.

Well as I said I hope you understand my question!

//Tekla
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Postby tekla » Sun Dec 02, 2012 11:42 am

Oh and a follow up question is, how can you possibly know if a change is due to phenotypic plasticity or genetic adaptation?
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Postby Luxorien » Sun Dec 23, 2012 9:08 pm

Interesting questions.

Since it is the organism's phenotype which will determine its reproductive success, I should think an organism's phenotype would influence the course of the species' evolution quite a bit. Even when the phenotype is variable, there's still an underlying genotype that could be affected by natural selection.

In the case of phenotypic plasticity, it is the ability to change one's phenotype that is selected for when the environment is variable. This ability is linked to a certain genotype (or set of genotypes). If the environment becomes more static, there is no longer any great benefit to phenotypic plasticity. This means that any individual organism without phenotypic plasticity may still reproduce, passing its static genes on.

In order for the lack of plasticity to become fixed, some other factor would have to come into play. In a small population, random genetic drift could cause the entire population to lose phenotypic plasticity. Or, plasticity might be selected against in a static environment because the ability to change one's phenotype might require a significant expenditure of energy. If competition for resources is fierce, this might lead to individuals without phenotypic plasticity edging out the individuals that still have it.

Basically, the environment will put certain pressures on the population. If the environment varies during an individual's lifetime, no specific phenotype will become fixed in the population because the environment will, at various times, be selecting different phenotypes. After a while, the ability to change one's phenotype is what is really being selected for. In an environment that stays the same, that ability is no longer advantageous, and we are back to one specific phenotype being selected. Since that phenotype could result from two different genotypes, I wouldn't expect either of them to become fixed unless some other factor comes into play. All the environment can "see" is the phenotype. It doesn't care what the genotype is, as long as the phenotype helps the organism reproduce.

As for the second question, I guess that would depend on what resources one has to investigate. I would think the easiest way to tell would be to take the organism out of its environment and put it in a new one. If it changes phenotype, then you have your answer. (I'm simplifying the necessary experimental procedure a bit, of course.)
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Postby tekla » Sat Dec 29, 2012 8:55 pm

Thanks for the answer, it was really helpful! It's really interesting but also a bit complicated, I think. Thanks again!
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