Which of the following is not a factor in sexual selection among fiddler crabs?

In the context of sexual selection among fiddler crabs, genetic drift is not a factor that influences mate choice or reproductive success. Sexual selection primarily operates through mechanisms that directly affect mating opportunities and preferences, such as male claw size, display behaviors, and female choice based on territory.

Male claw size plays a crucial role because larger claws can attract more females, signaling health and fitness. Similarly, display behaviors are important as males often use elaborate movements or gestures to capture the attention of potential mates. Female choice based on territory is also significant, as females may select mates based on the quality or attractiveness of the male's territory, which is often tied to resources and protection.

In contrast, genetic drift refers to random changes in allele frequencies within a population, which can affect genetic diversity but does not directly influence the sexual traits or selection processes that determine mating success. Thus, while genetic drift can shape the gene pool over time, it does not participate in the active selection that occurs in sexual selection among fiddler crabs, making it the correct choice for this question.