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Wayne State University researcher argues that sex reduces genetic variation

Wayne State University - Office of the Vice President for Research


Heng and fellow researcher Root Gorelick, Ph.D., associate professor at Carleton University in Canada, propose that although diversity may result from a combination of genes, the primary function of sex is not about promoting diversity. Rather, it's about keeping the genome context - an organism's complete collection of genes arranged by chromosome composition and topology - as unchanged as possible, thereby maintaining a species' identity. This surprising analysis has been published as a cover article in a recent issue of the journal Evolution.

"If sex was merely for increasing genetic diversity, it would not have evolved in the first place," said Heng. This is because asexual reproduction - in which only one parent is needed to procreate - leads to higher rates of genetic diversity than sex.



In fact, two billion years ago in Earth's biosphere, life relied exclusively on asexual reproduction, and every organism was capable of bearing young without costly competition to mate. With asexual species' faster and more efficient mode of reproduction, the origin and maintenance of sex - not exactly the fittest means of reproduction - puzzles scientists, who for decades have been asking, Why has sex evolved and survived?


According to Heng, the hidden advantage sex has over asexual reproduction is that it constrains macroevolution - evolution at the genome level - to allow a species' identity to survive. In other words, it prevents "Species A" from morphing into "Species B." Meanwhile, it also allows for microevolution - evolution at the gene level - to allow members of the species to adapt to the environment.



