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Monday, October 27, 2008

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More on the evolution of sex

I have written and published on this before. Here, for example.

What I have tried to show is that conflict in a cell between a majority of normal, functioning chromosomes and a smaller number of ineffective, parasitic chromosomes could have led to the evolution of sex. This is because the recombination of chromosomes due to gamete and zygote formation would have tended to advantage the normal chromosomes and disadvantage the parasitic chomosomes. I have given the results of the relevant simple calculations at the above link.

It occurred to me recently that the relative advantage for normal chromosomes in sexual reproduction would be strengthened in the case of multicellular organisms, since they can produce many gametes and the statistical likelihood is that - for the normal chromosomes - there will be a definite advantage in sexual reproduction. However in the case of a single celled organism, sexual reproduction is more of a risk because although it is likely that it will leave a normal chromosome better off, it is not certain, as there is a small risk that it will end up worse off. This might help explain why sexual reproduction is more typical of multicellular organisms.

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