Data from: Predation shapes the evolutionary traits of cervid weapons

Sexually selected weapons evolved to maximize the individual reproductive
success of males in many polygynous breeding species. Many weapons are
also retained outside of reproductive periods for secondary reasons, but
the importance of these secondary functions is poorly understood. Here we
leveraged a unique opportunity from the predator–prey system in northern
Yellowstone National Park, WY, USA to evaluate whether predation by a
widespread, coursing predator (wolves) has influenced a specific weapon
trait (antler retention time) in their primary cervid prey (elk). Male elk
face a trade-off: individuals casting antlers early begin regrowth before
other males, resulting in relatively larger antlers the following year,
and thus greater reproductive success, as indicated by research with red
deer. We show, however, that male elk that cast their antlers early are
preferentially hunted and killed by wolves, despite early casters being in
better nutritional condition than antlered individuals. Our results run
counter to classic expectations of coursing predators preferring
poorer-conditioned individuals, and in so doing, reveal an important
secondary function for an exaggerated sexually selected weapon—predatory
deterrence. We suggest this secondary function played a key evolutionary
role in elk; uniquely among North American cervids, they retain their
antlers long after they fulfil their primary role in reproduction.