Thursday, October 18, 2012

More thoughts on why sex evolved 

My earlier thoughts on the evolution of sex are given here:


and here:


They have been cited by Glansdorff et al. in the Journal of Molecular Evolution in 2009, here:


and are mentioned in the Wikipedia article on intragenomic conflict:


Further thinking has led me to take a broader perspective on the problem, and I shall gradually add more material to this post. The main point remains: that sex evolved because it is to the advantage of the genetic material itself. This is because the genetic material is able to recombine into desirable new combinations in offspring that proliferate well, thereby favouring the genetic material itself.

Sex provides continual improvement in the genetic makeup of organisms. Unlike the genetic material in asexual organisms; which will have no such way of entering new, more effective combinations; genetic material in sexual organisms will be able to recombine into more efficient and adaptive combinations. Individual organisms containing such effective combinations will proliferate well and the genetic material they contain will tend to dominate the next generation. In short, genetic material that codes for sex will proliferate more effectively than genetic material that does not.

Most theories on why sex evolved discuss sex in terms of its advantage to the individual organism or to the population. My approach focusses on the advantage to the genetic material itself in coding for sex.

Sex provides opportunities for all the chromosomes or genetic elements to form new combinations with other genetic elements which may a) combine better to produce a more effective genetic makeup for the carrier organism and b) introduce new, more adaptive mutations and c) allow less effective traits to be ameliorated by combination with traits that make up for the defect. In some cases, which I have already discussed previously, genetic elements which are seriously defective are effectively expunged by the sexual process.


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