Sexual selection

Definition

Sexual selection is a mode of natural selection where individuals with certain inherited traits are more likely than others to obtain mates. This process can lead to the development of secondary sexual characteristics that may not necessarily enhance survival but increase reproductive success, highlighting the importance of mating preferences and competition among individuals in the evolutionary process.

5 Must Know Facts For Your Next Test

1. Sexual selection can lead to exaggerated traits, such as peacock tail feathers, which may decrease survival but increase mating opportunities.
2. There are two main types of sexual selection: intersexual selection, where one sex chooses mates based on specific traits, and intrasexual selection, where individuals compete for access to mates.
3. Sexual selection plays a crucial role in speciation, as it can drive the divergence of populations through changes in mate preferences.
4. The strength and direction of sexual selection can vary greatly depending on environmental conditions and social structures within species.
5. Sexual selection is an essential mechanism that works alongside natural selection, influencing not just physical traits but also behaviors related to reproduction.

Review Questions

• How does sexual selection differ from natural selection in terms of its impact on evolutionary processes?
  • Sexual selection focuses specifically on reproductive success rather than survival. While natural selection emphasizes traits that enhance survival in a given environment, sexual selection highlights traits that improve an individual's chances of mating. For example, vibrant colors or elaborate courtship displays may attract mates but could also make individuals more visible to predators, illustrating how sexual selection can drive the evolution of traits that might not favor survival but are advantageous for reproduction.
• Discuss how sexual dimorphism is related to sexual selection and provide an example.
  • Sexual dimorphism refers to the distinct differences in appearance between males and females of a species, often resulting from sexual selection pressures. For instance, male deer grow large antlers primarily for fighting with other males during mating season to establish dominance and gain access to females. This characteristic evolves because it confers a reproductive advantage despite potentially being disadvantageous in terms of survival due to increased visibility to predators.
• Evaluate the implications of mate choice on the evolution of species and the potential consequences for biodiversity.
  • Mate choice significantly influences the evolution of species by shaping reproductive traits and behaviors, which can lead to speciation. Preferences for certain traits can result in divergent evolution when populations become separated geographically or ecologically, causing distinct adaptations to arise. This process enhances biodiversity by creating new species adapted to their environments. However, if mate choice leads to a narrow focus on specific traits, it could also threaten genetic diversity within populations and impact their resilience to environmental changes.

Related terms

mate choice: A behavioral phenomenon where one sex selects a partner based on specific traits, often leading to the evolution of those traits in the opposite sex.

intrasexual competition: Competition between individuals of the same sex for access to mates, often resulting in the evolution of traits that enhance fighting ability or dominance.

sexual dimorphism: The differences in physical characteristics between males and females of the same species, often resulting from sexual selection pressures.