Fig. 4. Independent contrast analysis of evolutionary change in relative melon area and evolutionary change in sexual dimorphism in body length for 21 species of cetacean. Positive values on the y-axis represent the evolution of an increase in the lateral projected area of the melon relative to the lateral projected area of the rest of the body. Negative values on the y-axis represent the evolution of a decrease in the lateral projected relative area of the melon. Positive values on the x-axis represent the evolution of longer males relative to females and negative values represent the evolution of shorter males relative to females. This result shows that species that have evolved relatively larger males tend also to have evolved relatively larger melons.