Trophic dimorphism in alternative male reproductive morphs of the acarid mite Sancassania berlesei

Presence of alternative male morphologies within a species has traditionally been related to different reproductive behaviors of morphs, and sexually selected weapons, that is, structures often present in a major male morph of a species, have been associated exclusively with competition between males over females. In this study, I show that alternative male phenotypes of the acarid mite Sancassania berlesei, one of the model male dimorphic species, differ in their foraging behaviors and diets. When food is deficient, aggressive "fighter" males use their weapons--thickened and sharply clawed third pair of legs, to kill conspecific juveniles and females, as well as individuals from at least one other species, which are subsequently consumed. Unarmed and benign "scrambler" males have no means of feeding in this way. The ecological importance and evolutionary consequences of this trophic dimorphism are unknown, but it might play an important role in fitness trade-offs between alternative male morphologies and, therefore, in evolution of conditional strategies. It might also increase the species' potential for rapid diversification and speciation. Copyright 2010, Oxford University Press.