Final answer:
The sex that shows higher variance in mating and reproductive success varies by species. Typically, males have more variability in their reproductive success due to competition and selective pressures, while females typically have more consistent reproductive success. However, in species with sex-role reversal, females may exhibit greater variance.
Step-by-step explanation:
Which sex shows higher variance in mating and reproductive success depends on the species and their specific mating strategies. In many animal populations, there is often more variability in the reproductive success of males than that of females. This is because males are sometimes larger, stronger, or more elaborately adorned and may have to compete with other males for mates, or be chosen by females, leading to some males having a lot of matings while others have none. On the other hand, sexual dimorphism can vary widely, and in some species with sex-role reversal, females may display greater variance in their reproductive success and be under selection for traits typically seen in males, such as larger body size.
For example, studies have shown that males, especially when sperm supplies are limited, will preferentially mate with larger females who are more fecund, thus maximizing their reproductive success. However, in cases where sexual dimorphism is reversed, females may have the greater variance in reproductive success. Overall, it's important to consider sexual selection and the specific ecological and biological context of the species in question when discussing variance in reproductive success.