MINI REVIEW Sexually antagonistic coevolution in insects is associated with only limited morphological diversity

Traits specialized for male–female interactions have long been known to commonly show rapid and divergent evolution, and thus to differ even among closely related species (West-Eberhard, 1983; Eberhard, 1985; Andersson, 1994). Traits such as courtship songs and male genitalia are often key traits for distinguishing species (e.g. Mayr, 1963) (Fig. 1). This rapid divergence has enabled taxonomists to use these structures as key traits for distinguishing species, and there is an immense, but under-utilized taxonomic literature, which allows surveys of the evolutionary patterns in these and other traits. Why this particular set of traits should tend to diverge rapidly continues to be debated (e.g. Hosken & Correspondence: William Eberhard, Escuela de Biologı́a, Universidad de Costa Rica, Ciudad Universitaria, San Jose, Costa Rica. Tel.: +506 228 0001; fax: +506 228 0001; e-mail: archisepsis@biologia. ucr.ac.cr