University of Indiana researchers found evidence that sexual reproduction may have begun as a way to avoid infection and death from parasites. Asexual reproduction is more efficient because it does not require a partner, but it also results in limited genetic variation. If a species has limited genetic variation, a parasitic species than can infect one organism might be able to infect the whole species, resulting in extinction.
Sexual reproduction inputs different genes into the new generation with each cycle. New genetic material in a host generally helps it prevent attacks and infection from parasites. The IU researchers tested the Red Queen hypothesis which is intended to explain the advantage of sexual reproduction, and the constant and sometimes deadly competition between species.
One of the lead researchers explained, “We were able to conduct a controlled test showing that exposure to coevolving parasites led to extinction of populations that could only self-fertilize, while populations that could have sex were able to survive and even adapt to the coevolving parasites.” (Source: io9.com)
In their experiment experiment bacteria became more infective, but the subjects that were reproducing asexually and therefore making genetic copies of themselves, did not get more resistant to the bacteria and eventually went extinct. The round worm Caenorhabditis elegans was used in the study.
Sex could be a strategy against co-evolving parasites, but the Red Queen hypothesis is not the only plausible explanation for its existence. The co-evolutionary activity might also be seen in the fact there are a number of pathogens also associated with sexual reproduction.
Image Credit: ChrisO
(Photo is an example of sexual dimorphism.)
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