Sex With a Partner Makes Evolutionary Sense: Study

Oct. 21 (HealthDay News) -- A new study in worms may help explain why reproduction via sex with a partner beats going it alone, evolutionarily speaking.

If a nematode worm wants to reproduce, they can do it one of two ways -- with a friend or alone -- but new research suggests that partnering up will boost the odds that the worms' children will live longer.

In the study, published in the Oct. 21 online edition of the journal Nature, scientists also found that reproduction via self-fertilization -- going it alone -- makes it more likely that genetic mutations will appear and reduces the chances that worm brethren will adapt to changes in the environment around them.

Researchers at the University of Oregon were interested in examining the worms, which are one of the animal and plant species that can give birth to offspring either by themselves (passing on all of their genes) or with the help of a mate.

In more than 100 experiments, the researchers exposed the worms to new environments, such as one in which a germ threatened to eat them. The scientists tracked the worms to see what happened to those that only self-fertilized versus those that only mated to reproduce, a process known as outcrossing.

The worms that only self-fertilized had more trouble coping with the world around them, which helps explain why so-called "selfing" groups are more likely to become extinct, study lead author and graduate student Levi T. Morran, explained in a university news release.

"Many scientists have argued that outcrossing has evolved to avoid the genetic consequences of inbreeding, while others have emphasized the role that outcrossing plays in generating the genetic variation necessary for evolutionary change," study co-author and University of Oregon biology professor Patrick C. Phillips, said in the news release. "Our work shows that both of these factors are important."

SOURCE: University of Oregon, news release, Oct. 21, 2009