Ecology and Evolution: Biology 301 -- Wethey
Department of Biological
Sciences
University of South Carolina
Evolution of Sex
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Evolution of Sex
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Why is sex advantageous?
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An organism that is asexual passes all its genes to its offspring, so it
leaves twice as many genes in the next generation as a sexual individual
that shares genes with its mate. By this logic there should be a 2 fold
advantage to diploid asexual organisms over diploid sexual ones.
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Lottery model - exceptional offspring are more important than numbers of
offspring. Asexual offspring are equivalent to lots of lottery tickets
with the same number, whereas sexual offspring each have a different lottery
number. However the correlation between sexuality and environmental uncertainty
is poor: it is more common among long-lived organisms in stable environments
than among short-lived organisms in fluctuating environments.
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Disease model - recombination provides generation by generation changes
in disease resistance.