SUBJECT: Origin of sex
DATE: 10/96
A few colleagues and I were halfheartedly debating as to when the idea
of sexual reproduction first occured. We threw around isogametes and
Chlamydomonas, conjugation in bacteria, Protoctista, etc. but never came
to any closure. Any suggestions from the experts out there?
Thanks ever so much.
T.Bennethum
Todd,
It's a very interesting question, with many competing points of view.
I'm no expert on the subject, but I once took a graduate course on this
topic. The text, "The Evolution of Sex", R.E. Michod and B.R.
Levin eds
1988, Sinauer Assoc. Pub. ISBN 0-87893-459-6 is filled with essays on the
subject. Many chapters are by noted "experts", J. Maynard Smith,
Michael
Ghiselin, Graham Bell, as well as the editors. You might want to check
it out, although my recollection from the course was that there are
several plausible and likely origins of sexual reproduction. Maybe you'd
like to offer a course on the subject just for the chance to explore it
some more!
Guy Farish
Biology Department
Adams State College
Alamosa, CO 81102
(719) 587-7969 FAX (719) 587-7242
To the List:
Several weeks ago there was a thread on evolution of sex, etc. I have a
possible reference of interest.
The Scientist January 8, 1996 pages13, 16.
Title of article: Biological Determination of Sexuality Heating Up As a
Research Field.
Interesting piece by Robert Finn.
Blystone in Texas
--------------------------------
Robert V. Blystone, Ph.D.
rblyston@trinity.edu
Department of Biology
Trinity University
715 Stadium Drive
San Antonio, Texas 78212
210.736-7243 FAX 210/736-7229
Todd,
I'm hardly an expert, but I've been noting references on this subject
for a few years. I've always been disturbed by the theories that claim
"sex evolved to promote genetic diversity," since besides being
shamelessly teleological, they seem to ignore the most successful
organisms on the planet: bacteria.
For many years Leonard Hayflick has advanced the idea that eukaryotic
cells, in general, must go through a phase of sexual reproduction
every few generations or their lineage will peter out and die. An old
review of his is in "Physiology of Cell Biology of Aging" edited
by A.
Cherkin in 1979. The very recent work on telomerase activity resetting
the "reproductive clock" has been interpreted in light of this
theory.
On a related theme, Bernstein & Bernstein edited a book called "Aging,
Sex, and DNA Repair" in 1991. In essence, the idea is that sex is an
outgrowth of the complicated mechanisms required for maintaining
those large floppy chromosomes we're stuck with.
If this notion is correct, sex is essentially as old as the origin of
eukaryotic cells, and species in which sex has never been observed
(e.g., amoebas) may actually be derived rather than primitive.
Food for thought anyway.
John Dickerman
Northern Illinois University
T80JWD1@WPO.CSO.NIU.EDU
Now this makes more sense to me than the source of variability does.
After all, haploid mosses seem to do just fine, although they do have the
advantage of sexual mixing. But dandelions do very well, yet are
apomictic. The theory is that dandeoions have mieosis, then combine the
products. The theory of maintaining large, floppy chromosomes would fit
well here, if they are able to cull out the misfits before combining their
own products. Hmm...does that work in something with one ovule per ovary?
More food for thought.
Janice
***********************************
Janice M. Glime, Professor
Department of Biological Sciences
Michigan Technological University
Houghton, MI 49931-1295
jmglime@mtu.edu
906-487-2546
FAX 906-487-3167
For the evolution of Human sexuality check out Lynn Margulis and Dorian
Sagan's text Mystery Dance.
-Mark Stephansky
Greetings,
The evolution and maintenance of sex has received a great deal of
attention in the literature lately and there is a very nice review of much
of this literature in the February 1996 issue of Trends in Ecology and
Evolution (TREE), Vol. 11, #2. In particular see the article by Laurence
D. Hurst and Joel R. Peck - Recent advances in understanding of the
evolution and maintenance of sex (pp. 46-52). Hope this helps.
Cheers,
Shawn
*******************************************************************************
Shawn Elizabeth Nordell, Ph.D. Phone: (818) 677-7866
Department of Biology FAX: (818) 677-2034
California State University, Northridge
18111 Nordhoff Street
Northridge, CA 91330-8303 E-Mail: Shawn.Nordell@CSUN.EDU