It Pays to Be Picky

The importance of picking a mate

• Hannah Schardt
• Feb 01, 2007

Scientists have long debated whether mate selection by females in the animal kingdom has any impact on the health and longevity of their offspring. Researchers from the University of Idaho tackled that question in a new study of a pronghorn population in Montana's National Bison Range and found that the answer is absolutely, at least among pronghorns.

Earlier genetic tests had revealed that a small group of males sired 60 percent of the population's young. In the study, lead author John Byers found that the offspring of these top males tend to be healthier and longer-lived than other young pronghorns. "In this species, and probably in a lot of species," Byers says, "female mate choice helps to maintain the genetic health of the population." So the females are choosy, but what is the basis of their choice? Byers previously determined that a male's horn size and body size have no bearing on his attractiveness as a mate. Instead, the females, which live in harems, watch to see which males are triumphant in exhausting, bloody battles during mating season—and avoid the losers. "It means that by the time a female reaches estrus, she is virtually guaranteed of being in the presence of a really vigorous male," says Byers.