Re: Non-Coding DNA preserved by genetic drift?
- From: "Malcolm" <regniztar@xxxxxxxxxxxxxx>
- Date: Tue, 20 Dec 2005 21:00:16 -0500 (EST)
<whitesickle@xxxxxxx> wrote
> "The data suggest it is genetic drift (an evolutionary force whose main
> component is randomness), not natural selection, that preserves junk
> DNA and other extraneous genetic sequences in organisms. When
> population sizes are large, drift is usually overpowered by natural
> selection, but when population sizes are small, drift may actually
> supersede natural selection as the dominant evolutionary force, making
> it possible for weakly disadvantageous DNA sequences to accumulate.
> Junk DNA costs energy to duplicate and to carry around as part of each
> cell. So natural selection operates against it. But if junk DNA gets
> generated by errors in replication faster than natural selection can
> select against it then junk DNA can accumulate."
>
There seems to be a bit of confusion between genetic drift and mutation
pressure.
Genetic drift is caused by chance over- or under- representation of alleles
in the next generation.
Mutation pressure occurs when the chance of A changing to B is greater than
the chance of B changing to A. Eventually B will come to predominate,
assuming no other forces.
This may be happening with junk DNA.
.
- References:
- Non-Coding DNA preserved by genetic drift?
- From: whitesickle@xxxxxxx
- Non-Coding DNA preserved by genetic drift?
- Prev by Date: Re: Lineage as unit of selection - was: Shall we get rid of our
- Next by Date: Re: Challenge - can anyone start life without an energy source?
- Previous by thread: Non-Coding DNA preserved by genetic drift?
- Next by thread: Re: Non-Coding DNA preserved by genetic drift?
- Index(es):
Relevant Pages
|
Loading
