Yes, most definitely. It is the degree of DNA sequence similarity (often
referred to as homology). This rests on the assumption (well proven in
simple organisms) that there is a constant mutation rate, and hence the
difference in DNA sequences between two organisms is a function of the time
since their common ancestor. This kind of analysis turns out to be highly
useful in practice -- though there is good evidence that the molecular clock
runs at different speeds in different branches of the evolutionary tree,
perhaps due to shorter generation times, more error prone DNA copying, or
greater selective pressure.
Francis
-----Original Message-----
From: alexanian@uncw.edu [mailto:alexanian@uncw.edu]
Sent: Thursday, April 04, 2002 10:02 PM
To: Collins, Francis (NHGRI)
Subject: RE: GENETICS
In a metric space, the notion of distance indicates how close one point is
from another. Is there an analogous notion of "distanceEUR in DNA space
that indicates how close a given species is from another?
Moorad Alexanian
Department of Physics
University of North Carolina at Wilmington
-----Original Message-----
From: gordon brown [mailto:gbrown@euclid.colorado.edu]
Sent: Tue 3/26/2002 3:55 PM
To: Collins, Francis (NHGRI)
Cc: asa@calvin.edu
Subject: RE: GENETICS
Dr. Collins,
I hope this question is not too vague. (It is far removed from my
field.)
I seem to recall having read somewhere that at least some of what
has been
considered to be superfluous junk DNA may turn out to have a useful
function. Can you comment on this?
Gordon Brown
Department of Mathematics
University of Colorado
Boulder, CO 80309-0395
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