variable mutation rate

Agner Fog ----Remove-to-reply----Agner at login.dknet.dk
Sun Mar 1 02:19:38 EST 1998


January Weiner <nospam_jweiner1 at ix.urz.uni-heidelberg.de> wrote:
>Cairns published some experimental results suggesting that during starvation 
>of some bacterial strains the rate of mutations events that enable the 
>bacteria to grow on a given substrate increases.  
>       Lenski and other experimental evolutionists showed that this
>pattern need not be attributed to directed mutation ("adaptative mutation"
>whatever that means). Starvation increases mutation rate independently of
>the influence of a given mutation on fitness.

The optimal mutation rate is a compromise between adaptivity and the cost of 
deleterious mutations. The optimum may be shifted towards higher mutation rate 
in case of adverse environmental conditions increasing the need for adaptivity.

Is there any evidence that any organisms 'actively' increase their mutation 
rate under adverse conditions?  By 'actively' I mean a specific evolved 
mechanism for regulating mutation rate, as opposed to haphazard mechanisms such 
as the organism having less resources for DNA repair when starving.

I haven't found any such evidence in the litterature. If it exists then please 
point to the reference.

====-------------------------agner at login.dknet.dk-------------------------====
Agner Fog, Ph.D.                 See my electronic book: 'Cultural Selection'
Denmark                          at:   http://announce.com/agner/cultsel




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