tag:blogger.com,1999:blog-7785493.post2863483322403506704..comments2024-01-04T04:11:55.717+02:00Comments on Dienekes’ Anthropology Blog: Or, maybe they speciated 3.7-6.6Ma ago? (Sun et al. 2012)Dienekeshttp://www.blogger.com/profile/02082684850093948970noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-7785493.post-32506904441312939292012-08-24T06:24:38.526+03:002012-08-24T06:24:38.526+03:00" Even a single mutation in a single individu..." Even a single mutation in a single individual, regardless of the size of the population, can make the difference between a mutationally limited community where no one has the variant needed to be more fit in a particular niche, and one where the mutation needed to survive best in an environment is within the range of natural variation". <br /><br />But that mutation still has to spread through the community (or species). What we know from the study of dairy cattle is that most mutations responsible for genetic change start out as recessive genes. Of course in the case of dairy cattle most mutations are harmful but I think we can safely extrapolate to advantageous genes. So a recessive, advantageous gene has to spread through numbers in a population before it can provide an advantage for members of that population. Perhaps its spread will be aided if it is co-dominant with the existing gene. terrythttps://www.blogger.com/profile/17327062321100035888noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-12160484627129234812012-08-24T03:07:27.932+03:002012-08-24T03:07:27.932+03:00One other explanation they offer up for the differ...One other explanation they offer up for the difference (in the text, but not in the note) is ascertainment bias, microsatellites are microsatellites because they are polymorphic and thus these alleles potentially have a higher mutation rate. <br />jeffhsu3https://www.blogger.com/profile/09614165485710166361noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-17719490012600506822012-08-24T01:10:23.206+03:002012-08-24T01:10:23.206+03:00I am skeptical that paternal age effects will have...I am skeptical that paternal age effects will have much impact on average mutation rates. Mutation rates are high in the low percentage of births to advanced paternal age fathers, fewer fathers lived to advanced ages in the past than they do now, and the age at which mutation rates become elevated is probably species specific - i.e. it is tied to the relative progression of the aging process not the absolute number of years that pass.<br /><br />But, paternal age may be much more important in evaluating natural selection models. In those models the issue is not the average mutation rate, but the likelihood that someone at some time gets born with a mutation that can provide a fitness advantage in a niche. Even a single mutation in a single individual, regardless of the size of the population, can make the difference between a mutationally limited community where no one has the variant needed to be more fit in a particular niche, and one where the mutation needed to survive best in an environment is within the range of natural variation. The faster the environment that needs to be adapted to changes and the smaller the effective population in question is, the more important mutational limitations are to ability of the community to utilize natural selection to adapt.<br /><br />A modest percentage of children born to fathers of advanced paternal age can tweak the extent to which a population is mutationallly limited much more strongly than it does the average mutation rate.<br />andrewhttps://www.blogger.com/profile/08172964121659914379noreply@blogger.com