Rise of the spiny ants: diversification, ecology and function of extreme traits in the hyperdiverse genus Pheidole (Hymenoptera: Formicidae)

Study of extreme phenotypic traits and novel structures provides insights into forces mediating evolution and diversification. Sexual selection is often implicated as the evolutionary driver of trait exaggeration, while examples invoking natural selection are scarce. Heretofore overlooked examples include outlandishly exaggerated spines produced by the non-reproductive castes of various ant lineages. Ant spines are conjectured to be defensive...