Population size and molecular clock?
Jose Mª Muiño
jmaria at teleline.es
Sat Jan 9 11:00:50 EST 1999
Mike Syvanen escribió en mensaje <76nrh6$lmb at net.bio.net>...
>"Jose Mª Muiño" wrote:
>> Ayala proved that the variability affect the speed of evolution, no?
>> If we have a high speed of evolution we´ll have a high variability,
>> If we have a high variability we´ll have a high heterozygosity (H),
>> if we have a high heterozygosity (H) we´ll have a high Ne, no?
>> Which is the problem?
>> larger populations experience more neutral
>> mutations (2NeV), but each neutral mutation has a smaller probability of
>> fixation (1/2Ne). Yes, but if Ne is very high some mutations can be the
>> same, and this 2NeV news mutations are less (i.e: 2NeV-x, where x are
>> mutations not news). Then K isn´t the same than V, isn´t it?
>Ayala's 1969 "proof" is not acceptable. Not because the logic is
>flawed, but because it leads to a result that does not explain patterns of
>molecular evolution as they are revealed in the sequence data. To a first
>approximation, the molecular clock is independent of population size.
Ayala never said the molecular clock is dependent of population size. He
only say that the variability affect the speed of evolution and this is
true, no? Then I think the rest.
And which is the problem of my idea?
Larger populations experience more neutral mutations (2NeV), but each
neutral mutation has a smaller probability of ultimate fixation (1/2Ne).
This isn´t true. A neutral mutation is |Ne*s|>1 then the probability of
ultimate fixation is 2*Ne*s/N, then K=4*Ne*s*m and Ne*s can be of 1 to -1 in
In small populations and in a finite time the effect of the drift is
more important than larger populations. Then, the clock of small
populations´ll not be than exact than larger population.
Larger populations experience more neutral mutations (2NV), but each
neutral mutation has a smaller probability of ultimate fixation (1/2N). Yes,
but if N is very high some mutations can be the same (the probabilty of that
two mutations are the same is more important in larger mpopulations), and
this 2NV news mutations are less (i.e: 2NV-x, where x are mutations not
news). Then K isn´t the same than V, isn´t it?
In fact, I think that K=2*Ne*V / 2*N
More information about the Mol-evol