Australasian Science: Australia's authority on science since 1938

Microbes Drove the Evolution of Sex

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University of Adelaide researchers have developed a computer simulation model that supports the theory that sexual reproduction evolved because of the presence of disease-causing microbes and the need to constantly adapt to resist these co-evolving pathogens.

“Asexual reproduction, such as laying unfertilised eggs or budding off a piece of yourself, is a much simpler way of reproducing,” says Dr Jack da Silva. “It doesn’t require finding a mate, and the time and energy involved in that, nor the intricate and complicated genetics that come into play with sexual reproduction. It’s hard to understand why sex evolved at all.”

According to the Hill-Robertson Interference theory, sex evolved because it allows the recombination of DNA between mating pairs so that individuals are produced that carry more than one beneficial mutation. Otherwise beneficial mutations compete with each other so that no single mutation is selected over another. However, da Silva says that this “elegant theory” doesn’t explain why sexual reproduction would be maintained in a stable, well-adapted population.

“It is hard to imagine why this sort of natural selection should be ongoing, which would be required for sex to be favoured,” he says. “Most mutations in an adapted population will be bad. For a mutation to be good for you, the environment needs to be changing fairly rapidly....

The full text of this article can be purchased from Informit.