Final answer:
In species with separate sexes, females generally have greater mate selection choice due to sexual selection, leading to prominent sexual dimorphism. However, this can vary, with some species exhibiting sex-role reversal.
Step-by-step explanation:
Parts of the fundamental asymmetry of life in species with separate sexes is that females typically exercise the greater degree of choice in the selection of mates. This pattern arises from sexual selection, which leads to more variance in reproductive success among males than females. In many species, some males—like the larger or more decorated ones—obtain the majority of matings, because they are either more capable of fighting off other males or because females prefer their elaborate traits. As a result, there is a strong selection pressure among males to obtain matings, leading to the evolution of features such as bigger body size and elaborate ornaments to attract female attention. Conversely, females are more likely to have fewer, but more selectively chosen matings, making them more discerning when it comes to mate choice.
In certain cases, the roles may be reversed, resulting in sex-role reversal. Here, females display traits typically associated with males, such as larger body size and elaborate characteristics. This happens in species where females have a greater variance in reproductive success. Overall, sexual dimorphism, which includes the physical and behavioral differences between males and females as a result of sexual selection, can vary widely among species.