Handsome Males Have Less Fertile Daughters

Take a look at Bruce Willis' case: how can the father be so hot and have a daughter who looks like a wack?

But this does not apply only to humans. Genes that enhance the manhood in males are not necessarily a beneficial heredity for the daughters, too. At least in red deer (Cervus elaphus), the best hunks that will beat all the other males, copulating with the entire harem, tend to have rather unsuccessful daughters. This could explain why lousy males still hang around, explaining this evolutionary paradox: why poor genes often persist and selection does not actually select only the "fittest" genes in time.

A team led by Katharina Foerster of the University of Edinburgh, UK, analyzed data gathered over the last 40 years from the Isle of Rhum, off Scotland's west coast. They assessed the success of individual deer based on their lifespan and the number and survival rate of the offspring they fathered.

They found that the most successful male deer tended to father daughters that weren't so successful.

"The daughters had less breeding success and produced fewer calves than average," says Foerster.

But the opposite was also valid: male deer carrying genes linked to higher female fertility didn't father as many calves. This mismatch solves the mystery of apparently "weak" traits surviving in natural populations.

"We see this sexually antagonistic selection because the male and female deer need to fulfill different requirements in order to be successful," says Foerster.

This twist on the battle of the sexes seems to occur in many species where there is sexual dimorphism (physical differences between the male and female).

Interestingly, a Spanish research showed that deer males carrying more "male" genes tended to father more males, while more "feminine" males tended to father more females... So, the battle of the sexes turns really interesting.

These genes could also explain the persistence of homosexuality in humans and nature: the too "masculine" males are more prone to have lesbian daughters and the too "feminine" mothers homosexual sons. It results that what booms sexual success on the "right", it dooms reproduction on the others. In the war between the sexes, all comes at a cost...

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