Raven and Johnston 5th edition, McGraw Hill.
It's not incorrect what they said. It's maybe simplified. It's not that sex
does not confer advantage to individuals. As I understand it, it's that sex
does not in every situation and every species and under every circumstance
benefit individuals more than asexuality - so it can be a puzzle. There are
apparently 2 books out at the moment by Mark and Matt Ridley, ironically, on
the 2 competing theories - the Red Queen: Sex and the Evolution of Human
Nature by Matt Ridley, and The Cooperative Gene: How Mendel's Demon Explains
the Evolution of Complex Beings by Mark Ridley (covers more of Kondrashav's
theory).
Wendee
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Wendee Holtcamp, M.S. Wildlife Ecology
Freelance Writer * Photographer * Bohemian
http://www.wendeeholtcamp.com
http://bohemianadventures.blogspot.com
~~6-wk Online Writing Course Start Apr 11 & Jun 6, 2009~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'Better to light a candle than curse the darkness'
-----Original Message-----
From: Wayne Tyson [mailto:[email protected]]
Sent: Friday, April 03, 2009 4:54 PM
To: Wendee Holtcamp; [email protected]
Subject: EVOLUTION Sex and Parthogenesis Re: [ECOLOG-L] clarification/
parthenogenesis & sex
Which biology textbook?
WT
----- Original Message -----
From: "Wendee Holtcamp" <[email protected]>
To: <[email protected]>
Sent: Friday, April 03, 2009 7:16 AM
Subject: [ECOLOG-L] clarification/ parthenogenesis & sex
> 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
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Wendee Holtcamp, M.S. Wildlife Ecology
> Freelance Writer * Photographer * Bohemian
> http://www.wendeeholtcamp.com
> http://bohemianadventures.blogspot.com
> ~~6-wk Online Writing Course Start Apr 11 & Jun 6, 2009~~
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 'Better to light a candle than curse the darkness'
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