Key points are not available for this paper at this time.
Douglas J. Emlen 1,*, John Hunt 2,†, Leigh W. Simmons 3,‡, Evolution of Sexual Dimorphism and Male Dimorphism in the Expression of Beetle Horns: Phylogenetic Evidence for Modularity, Evolutionary Lability, and Constraint, The American Naturalist, Vol. 166, No. S4, SEXUAL DIMORPHISM: ITS CAUSES AND CONSEQUENCESA Symposium Organized by Lynda F. Delph (October 2005), pp. S42-S68
Emlen et al. (2005) studied this question.