Understanding dimorphism as a function of changes in male and female traits.

I once received a review of a manuscript that took exception to the analysis of sexual dimorphism because the phenomenon is reified from independent changes in male and female characters. The reviewer was both right and wrong. Sexual dimorphism, a difference between males and females of a species in any anatomical, physiological, or behavioral character, is real in the sense that it reflects some underlying difference between the sexes. The fact that the magnitude of these differences varies among species in a measurable and constant way suggests that the phenomenon has a biological basis. But it is also true that dimorphism is a product of independent changes in male and female traits. It is becoming more and more apparent that a complete understanding of the phenomenon of sexual dimorphism can be achieved only by understanding variation in the factors that affect both male and female traits, and the potentially different responses to those factors in each sex.