Molecular Clocks & Generation Time

Daniel Weinreich dmw at MCZ.HARVARD.EDU
Fri May 5 08:26:59 EST 1995

On 5 May 1995, Ingrid Jakobsen wrote:

> In article <3o9q5g$rl6 at owl.und.ac.za>, daceh at shrike.und.ac.za (Halford Dace) writes:
> |> tend to `speed up' the molecular clocks of organisms with shorter
> |> generatioal times, since more generations (ie more gametogenesis &
> |> fertilizations) in a given period would allow more mutations to
> |> accumulate, since the genes comprising the population's gene pool
> |> would have spent a greater proportion of time as gametes.
> I'm not quite sure I understand Hal's idea, but if the significant part
> of the argument is the proportion of time spent as gametes, surely the
> mutation rate would be much higher in females of a species than males,
> since gametogenesis takes place very early in females, while in males,
> gametogenesis happens close to the time of fertilization. 
> Ingrid

Hal suggested another way of thinking about it to me yesterday:

> Mutations which occur within a few cell cycles of fertilization
> are obviously more likely to be incorporated into the germ line, so for
> instance an population which has 500 generations per century should
> accumulate more mutations than one which has 4 generations within the same
> period.

This seems to me to hold water; any comments?

Daniel M. Weinreich			email: dmw at mcz.harvard.edu
Harvard University 			usmail: 26 Oxford Street
Museum of Comparative Zoology			Cambridge, MA 02138
voice: (617) 495-1954			fax: (617) 495-5667

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