About a year and a half ago, I interviewed Erin McCullough of University of Montana about her research on the evolution of rhinoceros beetle horns; she published that work in July in Proceedings of the Royal Society B.
I was excited to see that a few months later in August, she published another related paper in PNAS. In this paper, she explores how the form and function of animal weapons is related to diversification of beetle horns. In the beetles she studies, males fight other males using their horns, in order to secure a mate. She found that male beetle’s horn structure is adapted to the typical fighting tactics used by his species.