Anyone Seen Evolution?

cboake at utk.edu cboake at utk.edu
Sun Nov 24 12:30:48 EST 1996


In article <sg32-ya023080002111961715360001 at newsstand.cit.cornell.edu>,
sg32 at cornell.edu (Susan Glueck) wrote:

> In article <57270p$t73 at scotsman.ed.ac.uk>, rhi at tattoo.ed.ac.uk (Rhiannon
> Macfie) wrote:
> 
> 
> > > Sounds like natural selection, can you expound on that.  How do I know 
> > >  there weren't a small percent of insects that were resistant to 
> > > the insecticide to begin with. 
>  
> > But where did this small percent come from in the first place?
> 
> Many insecticide resistance mutations involve a minor (minor in the sense
> of requiring only a small point mutation) alteration in amino acid sequence
> of a particular receptor protein which renders the particular pesticide
> ineffective. 


Please be aware that mutation is not evolution.  Mutation provides the
ultimate raw material upon which natural selection can act.

__Evolution requires both natural selection and genetic variation.__

  Whether that genetic variation arose from a new mutation, or was already
in the population at a low frequency, or moved into the population due to
an immigrant with some different DNA, is totally irrelevant to the
process.

The evolutionary response to selection, or the change in the mean
phenotype from generation to generation, is the product of inheritance and
selection.  If you express inheritance as heritability (or its
multivariate equivalent), and selection as the selection differential (or
its multivariate equivalent), the response to selection is in fact the
mathematical product of both.

Cheers,
Chris Boake



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