Final answer:
The sex with lower reproductive potential tends to be selective in mating to maximize evolutionary fitness. Sperm-depleted males, for example, choose larger, more fecund females to improve the success rate of offspring.
Step-by-step explanation:
Within a species, the sex that has the lowest reproductive potential may be expected to be more selective in mating, choosing partners that increase their chances of successful offspring.
An explanation derived from the provided reference material suggests that in conditions where resources like sperm are limited, sexual behaviors and mate selection can change significantly. For example, sperm-depleted males prefer mating with larger, more fecund females, optimizing their scarce resources for successful reproduction. Fecundity is often inversely related to parental care, as species that produce a high number of offspring tend to provide minimal care, maximizing their energy use for reproduction rather than offspring nurturing. In contrast, energy expenditure on elaborate courtship or attractive traits can result in less energy available for subsequent parental care. These reproductive strategies are ultimately driven by the need to maximize evolutionary fitness, ensuring gene propagation.