Just to clarify, since a couple asked offlist, what I meant when I said sex
does not have adaptive advantage to the individual, that comes from this in
my basic Biology textbook:
"Sex is of great evolutionary advantage for populations or species...However
evolution occurs because of changes at the level of individual survival and
repro....no obvious advantage accrues to the progeny of an individual that
engages in sexual repro. In fact recombination is a destructive as well as a
constructive process in evolution....The segregation of chromosomes during
meiosis tends to disrupt adv combos of genes more often than it creates new,
better adapted combinations... In fact the more complex the adaptation of an
indiv organism, the less likely that recombination will improve it and the
more likely that recomb will disrupt it. It is therefore a puzzle to know
what a well-adapted individual gains from participating in sexual repro
since all of its progeny could maintain its successful gene combinations
reproduced asexually"
I understand that there are 2 reigning theories at present on the evolution
of sex. One is the deleterious mutation hypothesis (Kondrashav) that sex
purges a species of genetic mutations (for this to be an evolutionary stable
strategy, according to his calculations anyway, the rate of deleterious
mutations must be less than 1 individual per generation, which is right
about the rate that deleterious mutations occur in most species).
The other is Van Valen's Red Queen hypothesis, which says sexual repro helps
individuals fight disease and parasites. The organism is in an ever present
red-queen-syndrome battle (running fast to stay in the same place) with
disease and parasites, and sex helps mix up the gene combos.
What I'm TRYING To understand is where/how does selfish gene theory fit in
with all this. Sometimes selfish gene theory seems at odds with Darwinian
selection on individuals, but sometimes it doesn't.
OK does that help clarify? Any insight??? :-)
Wendee
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Wendee Holtcamp, M.S. Wildlife Ecology
Freelance Writer * Photographer * Bohemian
http://www.wendeeholtcamp.com
http://bohemianadventures.blogspot.com
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