Aug. 11, 2008 Over the past two decades, John Byers has proven that female pronghorns are smarter than many humans when it comes to mate selection. Rather than going for the male with the biggest body or most impressive horns, female pronghorns expend a ton of energy searching for the most vigor and best stamina; traits that will give their offspring the greatest chance of success.
But are they smarter than classical European royalty? When pronghorns select a mate, can they factor in what many historians believe doomed the famous Hapsburg dynasty – inbreeding?
Thanks in part to a four-year, $600,000 grant from the National Science Foundation, Byers will be able to answer that exact question.
“We’ve shown the pronghorns know the benefit of selecting the best males,” said Byers, a professor of biological sciences at the University of Idaho. “Now we’re trying to show whether females can balance the cost benefits of selecting a strong male versus a closely related one. Will they accept mating with a relative if the projected cost of inbreeding is not too high? Or reject the male because the cost is way off the chart? Or will they breed without any regard to genealogy?”
Because Byers has worked with the same pronghorn herds in eastern Montana since the early 1990s, and can identify each pronghorn by sight, he is in a unique position to carry out this study. During that time, he has proven female pronghorns expend 50 percent more energy while searching for the strongest males, and that offspring sired by the chosen few are stronger, have a much higher chance of survival and strike out from their mothers much sooner. Because of this mate testing, nearly all offspring are sired by a small subset of males.
As a result of his research, Byers has a complete pedigree of the entire population. When a fawn is born, genetic testing removes any doubt which male is the father.
When a drought in 2003 killed off most of the males and about 30 percent of the females, Byers knew he was in a unique place to study mate selection based on inbreeding.
“I realized we were going to be in an incredibly interesting position,” he said. “We now know females select males for their vigor with a real benefit in survival for their offspring. But today, about three years after the weather caused a bottleneck in the population, they’re faced with a different set of choices.”
Byers’ research will be two-fold. First, the research team will test the paternity of new fawns, measure their living conditions and monitor their survival rate to see what, if any, negative effects occur in pronghorns from inbreeding. Once that is determined, scientists will study female behavior to see if females avoid closely related males – even the best choices for mates – if the benefits of strong genes are outweighed by the average negative effects of inbreeding.
“I think they’ll be able to discern the best choice,” said Byers. “But only time will tell.”
The results of Byers’ study should help conservationists keep the population of pronghorns – and perhaps many other types of hoofed animals – healthy in the future.
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