Possible subject on evolution...

January Weiner nospam_jweiner1 at ix.urz.uni-heidelberg.de
Thu Jan 15 11:06:11 EST 1998


[D.]:
> Hi all,

> Can anyone suggest a good topic concerning evolutionary emphasis and is
> fairly controversial.

	Maybe the directed mutation controversy? 
	Cairns suggested in late 80s that there are mechanisms which
increase the probability of adaptive mutations. Actually, this is a modern
form of lamarckism, neglecting one of the core paradigms of the modern
synthetic theory of evolution, i.e. that mutations are neutral, as showed
by Luria & Delbrueck and Lederberg in the 40s and 50s. 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. But Cairns in following
papers claims to have eliminated this possibility.
	There have been some new articles in Nature last year concerning
this subject. Here are some older references to start with:
	Sniegowski and Lenski, 1995. Mutation and adaptation: the directed
mutation controversy in evolutionary perspective. Annu. Rev. Evol. Syst.
26:553-78.
	Cairns J., Foster PL. Adaptive reversion of a frameshift mutation
in E. coli. Genetics 128:367-81

			January Weiner 3

-- 
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