Mol Evol and Mol Biol dilemma

Brian Foley btf at
Thu Jan 16 17:28:32 EST 1997

John Demboski wrote:
>       I would like people's opinions/comments/thoughts on 
> the relationship between molecular evolution and molecular 
> biology.
>     Let me explain.  
> ... more deleted here ...
>    Maybe it is just the program I am in, but i never realized there was
> such a rift between the various disciplines.  To me, there is so much
> overlap, I don't know how you can dismiss one or the other and draw such
> sharp boundaries between them.

	They are all sciences, and science seeks to find truths or
build models that explain our universe.  Each science sub-specialty
must agree with and build upon the truths and models of others. 
For example biology cannot defy the laws of thermodynamics.
	However, humans have many needs for classifing things,
including scientific sub-specialties.  If a person is using
DNA sequences to study the dynamics of a population of
tuna, they are just using molecular biology tools in the
study of tuna, they are not molecular biologists.  Just because a
microbiologist uses a microscope for many purposes, his
field of study is not optics.
	If you study the chemical properties and reaction rates of
a DNA polymerase, you are in biochemistry.  If you compare the
DNA sequences of human DNA polymerases and other mammalian DNA
polymerases to build a phylogenetic tree you are probably in
molecular evolution.  
	In some cases there is huge overlap, and in other cases there
is almost no overlap between two specialties which are both using
molecular biology tools.  But one can never "dismiss" other fields
of science.  In most cases the microbiologist does not need to
know very much of the physics and optics that make the microscope
so useful, and the microscope manufacturer may not need to know
much about microbiology.  But that does not mean that each one
"dismisses" the other.
	Molecular biology and molecular evolution have huge
overlaps in some cases, but in other cases they can be very
discrete fields of study.  Using the very same DNA sequence data
a molecular biologist may use the fossil record, and "molecular
clock" information to look at a bias in mutation rates of 
CpG dinucleotides due to DNA methylation patterns, while a
molecular evolutionist may use the fossil record, knowledge
of methylation patterns, and other mutation-rate biases to 
fine-tune the molecular clock estimates for the species under study.

> Cheers,
> John Demboski
> University of Alaska Fairbanks

|Brian T. Foley                btf at                      |
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