Handicap hypothesis implies emergence of dimorphic mating displays
Sara M. Clifton, Rosemary I. Braun, Daniel M. Abrams

Since 1975 Zahavi’s handicap principle has provided an elegant explanation for extravagant ornaments in the animal world: namely, that ornaments advertise fitness and must be costly in order to enforce honest signaling. Here, we show that populations of animals subject to the handicap principle may be forced to split into distinct subgroups of differing ornament size. We verify our claims via simple mathematical analysis and real-world data, including a composite data set of ornament size distributions from many distinct species, all of which are consistent with model predictions.