Final answer:
Sexual dimorphism refers to visible differences between the sexes of the same species, such as size and coloration, often caused by the differing reproductive strategies and selection pressures facing males and females.
Step-by-step explanation:
The term sexual dimorphism refers to the differences in physical characteristics between males and females of the same species, beyond the reproductive organs. This includes differences in size, coloration, and ornamentation, which are often a result of sexual selection and can significantly vary among different species. For instance, male peacocks display elaborate, colorful tails, while peahens are more subdued in appearance.
In some instances, these traits arise from the fact that there is often more variance in the reproductive success of males than females. Males that are larger or more decorated might have a higher rate of mating success, either through dominating other males or being chosen by females, leading to a selection pressure for such traits. In contrast, females typically have fewer opportunities for mating and therefore invest in selecting the more desirable males, which sometimes results in females being larger or more ornamented in species with sex-role reversal.
To illustrate sexual dimorphism, consider the eastern gray kangaroo, where dominant males tend to be larger and have an advantage in mating, highlighting how physical variance can contribute to reproductive strategies within mammal species.