Punctuated equilibrium and molecular clocks?

Johnjoe McFadden j.mcfadden at surrey.ac.uk
Wed Sep 2 10:16:45 EST 1998

Punctuated equilibrium and molecular clocks?

The punctuated equilibrium hypothesis of Gould and Eldridge, in which
evolution is proposed to go through long periods of stasis interspersed
with bursts of rapid evolution, is of course related to the fossil
record. However, periods of rapid evolution should also leave their
trace in molecular clocks. 

Does the phylogenetic analysis of protein gene sequences suggest that
their evolution has in some cases been episodic? I guess the evidence,
if it existed, would come from comparison of sequence divergence of a
protein like globin with a molecular clock sequence (e.g. ribosomal RNA)
for the same group of species. Is their any evidence that over
geological periods of time (measured by the clock sequence) the protein
undergoes episodic bouts of evolution?

Carl Wooese did suggest that mycoplasmas have gone through a rapid burst
of evolution on the basis of ribosomal RNA sequences but is there any
other evidence?

Johnjoe McFadden

Johnjoe McFadden, PhD
Reader in Molecular Microbiology
School of Biological Sciences
University of Surrey
Guildford, Surrey, GU2 5XH
Tel: (44) 1483 300800 x2671
Fax: (44) 1483 300374
Email: j.mcfadden at surrey.ac.uk

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