Strong, silent types: the rapid, adaptive disappearance of a sexual signal

To see evolution in action, it helps to be in the right place at the right time. In a recent study, Zuk et al. document the rapid evolution of a sexual signal in crickets on a Hawaiian island and suggest that it is a response to parasitism. A new male morph has appeared that cannot sing, and so does not attract an acoustically orientating parasite. The disadvantage of this, however, is that silent males might not be able to attract mates. The authors suggest that plasticity in male aggregating behaviour can provide an escape from the costs of this potentially maladaptive trait.