Bred to win?
Good genes don't guarantee a champion.

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In Horse Breeding, Genes Aren't Always a Good Bet

When it comes to success on the racetrack, nurture beats nature by a mile, new research suggests. A Scottish team has found that horse breeders who pay the highest stud fees to mate their mares with popular stallions--hoping to cash in on the bloodlines of a champion--won't necessary make out any better in the winner's circle.

It's a time-honored tradition in the Sport of Kings: Racehorses that ring up the biggest winnings on the track also command the highest fees when put out to stud. The rationale is understandable--the offspring of winners are likely to be winners themselves. But that's not what two evolutionary biologists found when they decided to see how well human breeders were succeeding at producing champion horses.

Alastair Wilson and Andrew Rambaut of the University of Edinburgh, U.K., analyzed the race results and purses of nearly 4500 offspring of thoroughbreds foaled between 1922 and 2003. Based on the lifetime earnings of those foals, they concluded that genetic links to previous champions had only a small effect on the amount of prize money--less than a 10% correlation. As they report online this week in Biology Letters, other factors, such as the farms where the horses were raised and the trainers employed to teach them how to race, exerted a considerably bigger influence--as much as a 90% correlation. "The best males are not necessarily those with the highest price tags," Wilson says. "People could potentially pay a lot of extra money to buy genes that are no better than average."

Evolutionary biologist David Coltman of the University of Alberta in Edmonton, Canada, agrees with the paper's conclusions. "It might be quite difficult to pick the right stud reliably based on genetics compared to the environmental effects," he says. Coltman adds that previous research had shown that stud fees correlate with the speed of the offspring, but the new findings indicate that the correlation doesn't necessarily translate into winning.

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