Re: Planet of the New Papers

[evelyn sobielski <koreke77@yahoo.de>]

--- David Marjanovic <david.marjanovic@gmx.at> schrieb am Fr, 23.5.2008:

> Von: David Marjanovic <david.marjanovic@gmx.at>
> Betreff: Re: Planet of the New Papers
> An: "DML" <dinosaur@usc.edu>
> Datum: Freitag, 23. Mai 2008, 1:54
> > Weir, J.T., and Schluter, D. 2008. Calibrating the
> avian molecular clock.
> > Molecular Ecology 17(10):2321-2328. doi:
> 10.1111/j.1365-294X.2008.03742.x.
> >
> > ABSTRACT: Molecular clocks are widely used to date
> phylogenetic events, 
> > yet
> > evidence supporting the rate constancy of molecular
> clocks through time 
> > and
> > across taxonomic lineages is weak. Here, we present 90
> candidate avian 
> > clock
> > calibrations obtained from fossils and biogeographical
> events.
> 
> Why do they even bother? Why don't they use a post-1995
> method that can, you 
> know, deal with rate variations and therefore doesn't
> require a strict clock 
> in the first place?
> 
> Or what have I missed?

Nothing it seems; people have been awfully slow to adopt nonstandard clocks. 
And I think the take-home message is that although the "2% rule" can be 
expected to apply to *most* lineages, the variance found across *all* lineages 
is so large that knowing the average rate is still fairly useless. Because each 
case in which it does not apply but is presumed to apply is likely to seriously 
mess up the analysis.


Eike


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