Sex with a partner best

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 journal Nature, scientists also found that reproduction via self-fertilisation -- 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.

How the study was done
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-fertilised versus those that only mated to reproduce, a process known as out crossing.

The worms that only self-fertilised 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 out-crossing has evolved to avoid the genetic consequences of inbreeding, while others have emphasized the role that out-crossing plays in generating the genetic variation necessary for evolutionary change," study co-author and University of Oregon biology professor Patrick C. Phillips, said. "Our work shows that both of these factors are important." – (HealthDay News, October 2009)

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