Why Have Sex? Why Not?

Reproducing Without Sex Promotes Helpful Mutations

From the WebMD Archives

Jan. 23, 2003 -- Why bother with sex? It's an oft-asked question in biological circles, since many species thrive just fine reproducing without having sex.

Turns out, solo reproduction does indeed offer an evolutionary advantage -- at least in some populations, writes lead researcher Clifford Zeyl, PhD, a biologist at Wake Forest University in Winston-Salem, N.C.

His research appears in the Jan. 24 issue of Science.

Zeyl details a study comparing yeasts that have only one set of chromosomes to yeasts with two sets of chromosomes -- as found in humans. Organisms with two chromosome sets typically reproduce sexually, although they were not allowed to in this experiment. Zeyl propagated both varieties of yeast for many generations, and measured how well the yeast were adapting to their culture conditions.

He found that reproduction without sex allowed helpful mutations to occur more frequently. This was an evolutionary advantage in large populations, he says. However, this benefit was lost on small populations, Zeyl adds.

SOURCE: Science, Jan. 24, 2003.

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