Jimmy Higgins

I've been told there are positive, negative, and neutral mutations. I was wondering whether a neutral mutation is doomed to eternity to remain a neutral change or given time can within a different environment become positive or neutral. Or can two neutral mutations make a positive, etc... etc...

What makes a mutation neutral?

RufusAtticus

"Neutral" is a relative term. An allele is neutral if it has no selective advantage or disadvantage compared to some other allele. Usually this comparison is made between a novel mutation and the "wild-type" allele. Definately neutrality can be affected by an environmental shift. On the molecular level mutations in the third base of a codon are usually neutral because for the most part they don't affect the protein encoded. Similar examples can be found amongst "junk-DNA."

Wounded King

I'd imagine you could categorise neutral mutations into two categories of 'true neutral' and 'situationally neutral'. A mutation leading to no change in aa structure, via 3rd base wobble or other ways, would be truly neutral while one leading to the substitution of a sufficiently equivalent aa to allow continued function of the protein might, in certain circumstances, prove deleterious or beneficial.

KC

The interaction of its phenotype with the environment. A neutral mutation can be come beneficial or detrimental should the ecological context in which it finds itself change.

KC

Jimmy Higgins

Thanks. I suspected that could be the case. So neutral mutations can become positive. They pass on because they are harmless, but given time could turn good or bad. I'm a rather critical person, but the more and more I hear about evolution, it just makes more and more sense. I don't get these anti-evolutionists, well other than their hubritic arrogence.

ps418

Sure they can. The CCR5 delta 32 allele that I mentioned in the mutation thread is a prime example. At one and the same time, it will be beneficial and under positive selection in environments where risk of HIV mortality is signficant, but neutral and under no selective pressure in envirionments where risk of HIV mortality is insignficant.

Patrick

NZAmoeba

You guys LOVE scientific terms don't you?

for the sake of the veiwers at home, i give "the childrens big book of scientific stuff" meaning.

People can have mutations that have no effect whatsoever, my sisters boyfriend recently discovered that instead of two kidneys, he has one big horseshoe shaped one.

The neutral mutations stay on, because evolution's theory is "whatever doesn't kill me, must only make me stronger". Then suddenly the environment changes, be it the weather, nuclear winter, new virus or new predator. With this new change, EVERYTHING gets re-evaluated. Things that were good before, can now get you killed, and things that served no purpose could suddenly become quite beneficial (or also get you killed...). This is why most new species show up during times of great environmental change.

You can go back to watching wrestling now

MortalWombat

This is technically not a mutation, but an abnormality that occurs during embryonic renal development. And I wouldn't quite go as far as saying that it has not effect whatsoever:

from here

NZAmoeba

Wouldn't a mutation essentially BE an abnormality?

And yeah, while he did discover his kidney shape while being treated for kidney stones, none of those medical conditions would affect natural selection as he's already lived to breeding age. This is why most of our debilitating medical conditions only take hold later in life, natural selection see's no need to get rid of it because you're living long enough to have kids.

All we need now is some new kidney disease that horseshoe kidneys are immune to, and we'll have ourselves another evolutionary step from a neutral mutation.

Doubting Didymus

Not really. Why do you say that? Given that every nucleotide on our genome was a mutation at some point, how long do you propose they need to stick around before they become 'normal'?