Sexual Selection Theory

Definition

Sexual selection theory is a concept in evolutionary biology that explains how certain traits evolve in species based on their appeal to potential mates. This theory posits that individuals with characteristics deemed attractive or advantageous are more likely to reproduce and pass those traits on to future generations. It emphasizes the role of mate choice and competition among individuals in shaping reproductive success.

5 Must Know Facts For Your Next Test

1. Sexual selection can lead to the development of extravagant traits, such as peacock feathers or deer antlers, which may not provide survival advantages but enhance mating success.
2. The theory highlights two primary mechanisms: mate choice (intersexual selection) and competition among the same sex (intrasexual selection).
3. Sexual selection can influence behavioral traits as well, including courtship rituals and displays that signal fitness to potential partners.
4. In some species, females are known to be the choosier sex, leading to males developing elaborate traits to attract them, while in others, males may compete directly for access to females.
5. Sexual selection can also create evolutionary pressures that result in population divergence and speciation over time.

Review Questions

• How does sexual selection theory explain the development of extravagant traits in certain species?
  • Sexual selection theory posits that extravagant traits evolve because they enhance an individual's chances of attracting a mate. These traits may not necessarily improve survival but signal genetic fitness to potential partners. For example, peacock feathers are visually striking and attract female peafowl despite their potential drawbacks in terms of predation.
• Compare and contrast mate choice and intrasexual competition within the framework of sexual selection theory.
  • Mate choice involves individuals selecting partners based on desirable traits that indicate fitness, often resulting in one sex being choosier. In contrast, intrasexual competition refers to individuals of the same sex competing for access to mates through physical confrontations or displays. Both mechanisms drive the evolution of different traits but focus on distinct aspects of mating behavior.
• Evaluate the implications of sexual dimorphism resulting from sexual selection on species evolution and biodiversity.
  • Sexual dimorphism can significantly influence species evolution by creating distinct male and female roles that affect reproduction strategies. These differences can lead to niche specialization, reduced competition between sexes, and ultimately increased biodiversity as populations adapt to varying ecological pressures. Over time, sexual selection can contribute to speciation events as divergent traits become pronounced enough to affect reproductive isolation between groups.

Related terms

Mate Choice: The process by which individuals select partners based on specific traits, preferences, or behaviors that signal genetic fitness.

Intrasexual Competition: A type of competition where individuals of the same sex compete for access to mates, often leading to the development of specific physical traits or behaviors.

Sexual Dimorphism: The differences in size, appearance, or behavior between males and females of the same species, often resulting from sexual selection pressures.