Sexual selection

Definition

Sexual selection is a form of natural selection where certain traits increase an individual's chances of attracting mates, leading to reproductive success. This process can drive the evolution of traits that may not necessarily enhance survival but improve mating opportunities, such as bright colors or elaborate courtship behaviors. Sexual selection can lead to the development of new species by creating distinct reproductive strategies and preferences within populations, as well as promote adaptive evolution by favoring traits that enhance mating success in specific environments.

5 Must Know Facts For Your Next Test

1. Sexual selection can occur through two main mechanisms: intersexual selection (mate choice) and intrasexual selection (competition among same-sex individuals).
2. Traits favored by sexual selection can lead to increased visibility to predators, suggesting a trade-off between attractiveness and survival.
3. Sexual selection is often more pronounced in species with high levels of parental investment, where mate choice plays a critical role in reproductive success.
4. The concept of sexual selection helps explain the diversity of mating systems seen across different species, including monogamy, polygyny, and polyandry.
5. Sexual selection can contribute to speciation by creating reproductive barriers as populations diverge in their mating preferences and strategies.

Review Questions

• How does sexual selection differ from natural selection, and what impact does this difference have on evolutionary processes?
  • Sexual selection differs from natural selection in that it specifically focuses on traits that enhance an individual's ability to attract mates rather than overall survival. While natural selection promotes traits that help organisms survive in their environment, sexual selection can lead to the evolution of extravagant features that may decrease survival but increase mating opportunities. This difference plays a crucial role in shaping the genetic diversity within populations and can influence the development of new species through distinct mating preferences.
• Discuss the role of mate choice in sexual selection and how it can lead to adaptive evolution in populations.
  • Mate choice is a vital aspect of sexual selection where individuals select partners based on certain traits, which can lead to adaptive evolution. For example, if females prefer males with brighter colors or more elaborate displays, those traits will be passed down through generations. As a result, the population may evolve to exhibit these favored characteristics more prominently. This process not only enhances mating success but can also shape the overall gene pool and drive evolutionary change as preferences shift in response to environmental factors.
• Evaluate how sexual dimorphism is influenced by sexual selection and its implications for speciation events.
  • Sexual dimorphism is heavily influenced by sexual selection as it often drives the evolution of distinct physical traits between males and females. These differences can arise from varying mating strategies; for instance, males may evolve larger size or more vibrant colors to attract females while females may develop traits favoring offspring survival. Such pronounced differences can lead to reproductive isolation as populations diverge in their mating preferences and characteristics over time. This reproductive isolation is a key factor in speciation events, allowing for the emergence of new species adapted to specific ecological niches.

Related terms

mate choice: A key component of sexual selection, where individuals select mates based on specific traits or characteristics, influencing genetic diversity and evolutionary outcomes.

sexual dimorphism: The differences in size, color, or morphology between males and females of the same species, often resulting from sexual selection pressures.

runaway selection: A theory suggesting that a trait can become exaggerated over generations due to the preference of one sex for that trait in potential mates, leading to increasingly elaborate features.