In sperm competition, what is 'second-male advantage'? a. the observation that when females mate with two males, each male fertilizes the same number of eggs b. the observation that when females mate with two males, the second male fertilizes most of the eggs c. the observation that females routinely mate with at least two males before laying eggs or becoming pregnant d. the observation that accessory fluids prevent matings by second males—for example, by forming copulatory plugs

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1. The 'second-male advantage' in sperm competition refers to option b: the observation that when females mate with two males, the second male fertilizes most of the eggs. This phenomenon is observed in many species and is thought to be due to various factors, such as the female's reproductive tract favoring the most recent sperm, or the second male's sperm outcompeting the first male's sperm.

Key Concepts

Sperm Competition

Sperm competition refers to the competitive process between sperm from different males to fertilize the eggs of a female. This phenomenon occurs when a female mates with multiple males, leading to a scenario where the sperm from these males compete within the female reproductive tract. Understanding sperm competition is crucial for analyzing reproductive strategies and evolutionary adaptations in various species.

Second-Male Advantage

The second-male advantage is a specific outcome observed in sperm competition, where the second male to mate with a female often fertilizes a greater proportion of her eggs compared to the first male. This advantage can arise due to various factors, such as the timing of sperm release, the displacement of the first male's sperm, or the female's reproductive physiology favoring the later male's sperm. Recognizing this concept is essential for understanding mating dynamics and reproductive success.

Mating Strategies

Mating strategies encompass the various behaviors and tactics that organisms employ to maximize their reproductive success. In the context of sperm competition and second-male advantage, these strategies can include timing of copulation, mate guarding, and the frequency of mating with multiple partners. Analyzing these strategies helps elucidate the evolutionary pressures that shape reproductive behaviors in different species.