Final answer:
Sexual dimorphism refers to the differences in size, appearance, or behavior between males and females of a species, which often arise due to sexual selection and can lead to traits like larger size or elaborate traits in one sex.
Step-by-step explanation:
Sexual dimorphism refers to differences in size, appearance, or behavior between males and females of a species. It is a biological term that denotes the presence of physical or physiological differences between the sexes, beyond the reproductive organs. In some species, sexual dimorphism can even reverse typical sex roles, resulting in females that are larger and display more elaborate traits which are characteristics usually associated with males.
Differences in reproductive success drive sexual selection, often resulting in males developing traits like bigger body size and elaborate decorations such as colorful plumage or ornamentation to attract females. These traits can be advantageous in competing for mates or being selected by mates, a phenomenon that illustrates the varying selective pressures on males and females. Sexual dimorphism is evident in many animal species, including the elaborate tail of a peacock versus the more subdued peahen, and the size disparity between male and female spiders and ducks, as shown in various examples like Figure 19.11.