Final answer:
Sexual dimorphism denotes the physical traits differentiating males and females of a species, such as body size, coloration, and adornments. Males may possess these traits due to sexual selection driven by competition or female choice, although some species show reversed roles, with dominant females displaying these traits.
Step-by-step explanation:
Sexual dimorphism refers to the differences in physical characteristics between males and females of the same species, beyond the reproductive organs. These differences can include variations in body size, coloration, and presence of ornaments such as the peacock's tail. Generally, male animals are selected for traits that enhance their chances of reproductive success, such as larger size, strength, or elaborate colors, which may be a result of either direct competition with other males or female choice. However, some species exhibit sex-role reversal where females are larger and more elaborately adorned. This trend may be influenced by variances in reproductive success and sexual selection, which involves different pressures that lead to distinct phenotypes between the sexes. Examples of sexual dimorphism can be seen in peacocks with their colorful tails, size differences in the Argiope appensa spiders, and the plumage of wood ducks. Furthermore, scientists caution against applying simplistic correlations between sexual dimorphism and social behaviors, indicating that behaviors and roles can form unique mosaics in different species. Thus, the characteristics of sexual dimorphism are complex and influenced by a mix of biological and social factors that can vary widely across the animal kingdom.