This is a preview. Log in through your library . Abstract When an individual’s reproductive success relies on winning fights to secure mating opportunities, bearing larger weapons is advantageous.

Abrupt shifts in the evolution of animals -- short periods of time when an organism rapidly changes size or form -- have long been a challenge for theorists including Darwin. Now a newly published ...

Title image: A juvenile prairie rattlesnake, one of the focal species in a new study, looks out from a rock outcrop near a den site in northern Montana. (Credit: Drew Schield) In the evolutionary arms ...

Evolution can perform spectacular makeovers: today's airborne songbirds descended from the wingless, earthbound dinosaurs that roamed millions of years ago, for example. But some organisms seem to ...