Unit Evolutionary Period - Is it still used?

Ron Kagan rkagan at ewald.mbi.ucla.edu
Mon Nov 28 15:06:53 EST 1994

Hello Evolutionists:

I've come across the concept of Unit Evolutionary Period (UEP), defined
as the number of years (MYR) required to cause a 1% change in
evolutioarily divergent sequences.
This concept was originally defined by Dickerson in 1971.  I have 2
questions, for those of you with expertise in molecular evolution:

1. Is it still exceptable to use UEP to quantify rates of evolution
(molecular clock) or is the UEP obsolete?  If it's obsolete, what has
replaced it?

2. If I use UEP, what would be preferable for representing the distances
between pairs of divergent proteins:  

A. the corrected pair distance, as given by the equation d =
-0.94*Ln(1-p/0.94) (where p is the observed number of aa replacements
between 2 sequences) or:

B. the divergence of the sequences as calculated from the phylogenetic
tree of the sequences involved using the DNASTAR program MEGALIGN, and
defined as:
100*distance (i,j)/total distance, which is the sum of the branch lengths
of the evolutionary tree.


Ron Kagan

"You cannot strengthen one by weakening another; and you cannot
 add to the stature of a dwarf by cutting the leg off a giant."

                                - Benjamin Franklin (1706-1790)

Ron Kagan
rkagan at ewald.mbi.ucla.edu

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