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Molecular Lattitude



Hello. 
Something of interest from SCIENCE, Volume 299, Issue 5613 
Editor's Choice: : Highlights of the recent literature
-mpc


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ECOLOGY/EVOLUTION: Molecular Latitude
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Andrew M. Sugden

Most groups of organisms obey latitudinal gradients in species richness, 
whereby numbers of species increase from the poles toward the equator.
The 
reasons for these gradients remain contentious. One proposal is that 
increased temperature and solar radiation lead to faster growth, shorter 
generation times, elevated mutation, and faster molecular evolution, all
of
which should combine to produce more rapid rates of speciation. Bromham
and
Cardillo investigated this proposal using a comparative test of the
rates 
of molecular evolution of mitochondrial and nuclear DNA in
phylogenetically
independent pairs of bird species from different latitudes. The
phylogenies
reconstructed from the sequence data indicated no statistically
significant
differences between rates of molecular evolution at different latitudes, 
arguing against the proposal that climatic factors directly influence
the 
speciation rate in birds. -- AMS

J. Evol. Biol. 16, 200 (2003).

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