Male genital titillators and the intensity of post-copulatory sexual selection across bushcrickets

Animal genitalia are diverse and a growing body of evidence suggests that they evolve rapidly under post-copulatory sexual selection. This process is predicted to be more intense in polyandrous species, although there have been very few comparative studies of the relationship between the complexity of genital structures in males and measures of the degree of polyandry. In some bushcricket families, males possess sclerotized copulatory structures known as titillators, which are inserted into the female’s genital chamber and moved rhythmically. Like other genital structures, bushcricket titillators are widely used as important taxonomic characters and show considerable variation across species in structure, shape, and the extent to which they are spined. Here, we examine relationships between the presence/absence of titillators, titillator complexity, and both mating frequency and the degree of polyandry in bushcrickets, using phylogenetic comparative analyses. Using published sources com...