Sexual selection

Definition

Sexual selection is a mode of natural selection where individuals with certain traits are more likely to successfully mate and pass on their genes to the next generation. This process can lead to the evolution of characteristics that improve mating success, such as bright plumage in birds or elaborate courtship behaviors. Sexual selection emphasizes the importance of mate choice and competition for mates, which can influence evolutionary outcomes in various species.

5 Must Know Facts For Your Next Test

1. Sexual selection can lead to the development of exaggerated traits, such as the peacock's tail, which may serve as an indicator of fitness to potential mates.
2. The two main components of sexual selection are mate choice and competition, where females often select mates based on traits that signal genetic quality.
3. Sexual selection can result in sexual dimorphism, where males and females exhibit different physical characteristics due to differing reproductive strategies.
4. In some species, such as certain fish or insects, male competition can be fierce and lead to the evolution of aggressive behaviors or physical adaptations.
5. Sexual selection operates alongside natural selection, but it can sometimes lead to traits that may be disadvantageous for survival, illustrating a trade-off between mating success and survival.

Review Questions

• How does sexual selection contribute to the evolution of species through mate choice and competition?
  • Sexual selection contributes to species evolution by influencing both mate choice and intrasexual competition. In mate choice, individuals select partners based on desirable traits that indicate genetic fitness, which can lead to increased reproductive success for those with favorable characteristics. In terms of competition, individuals may develop traits or behaviors that enhance their chances of outcompeting others for mates. This dynamic shapes the genetic diversity within populations and drives evolutionary changes over generations.
• Discuss the implications of sexual dimorphism in relation to sexual selection and how it affects reproductive strategies.
  • Sexual dimorphism arises from sexual selection when males and females evolve distinct physical traits based on their differing reproductive strategies. Males may develop larger sizes, vibrant colors, or elaborate features to attract females or compete with other males. In contrast, females may prioritize traits that ensure better offspring survival over flashy attributes. This divergence highlights how sexual selection shapes not only physical characteristics but also behaviors related to mating and parenting within species.
• Evaluate the interplay between sexual selection and natural selection in shaping evolutionary outcomes in different environments.
  • The interplay between sexual selection and natural selection is crucial in shaping evolutionary outcomes. While natural selection focuses on survival traits that enhance an organism's ability to thrive in its environment, sexual selection emphasizes traits that improve mating success. In environments where mate availability is limited or specific traits signal superior genetics, sexual selection can lead to extreme characteristics that may not necessarily benefit survival. This tension creates a complex evolutionary landscape where organisms must balance the advantages of mating success against potential survival costs.

Related terms

mate choice: The selection of a partner based on specific traits or characteristics that are perceived as advantageous for reproductive success.

intrasexual competition: Competition among individuals of the same sex, typically males, for access to mates, which can lead to the evolution of traits that enhance fighting ability or dominance.

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