Sexual selection

Definition

Sexual selection is a form 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, such as elaborate feathers or mating calls, which may enhance an individual's attractiveness to potential partners. It plays a crucial role in speciation by influencing reproductive isolation and divergence between populations.

5 Must Know Facts For Your Next Test

1. Sexual selection can lead to pronounced differences between male and female individuals, known as sexual dimorphism, which can include size, color, and behaviors.
2. This form of selection operates through two main mechanisms: mate choice and intrasexual competition, both influencing the evolutionary path of species.
3. Sexual selection can drive speciation by creating reproductive barriers, where populations develop distinct traits that affect mate preference, leading to isolation.
4. The concept was introduced by Charles Darwin as part of his theory of evolution, highlighting its significance alongside natural selection in shaping biodiversity.
5. In some species, extravagant traits that might seem disadvantageous for survival (like bright colors) can actually increase mating success due to female preferences.

Review Questions

• How does sexual selection differ from natural selection in terms of its effects on a population's traits?
  • Sexual selection differs from natural selection primarily in that it specifically focuses on traits that affect mating success rather than survival. While natural selection promotes traits that enhance an organism's ability to survive and reproduce in its environment, sexual selection favors traits that make individuals more appealing to potential mates. This can result in exaggerated features or behaviors that may be detrimental to survival but advantageous for attracting mates, leading to unique evolutionary pressures within a population.
• Discuss the role of sexual selection in speciation and how it contributes to reproductive isolation among populations.
  • Sexual selection plays a key role in speciation by promoting reproductive isolation between populations. As certain traits become favored within a population—such as specific colors, displays, or calls—individuals may preferentially choose mates with those traits. This selective pressure can lead to divergence as populations evolve distinct mating preferences and associated traits over time. Eventually, if these changes become significant enough, individuals from different populations may no longer recognize each other as potential mates, resulting in reproductive isolation and the potential for new species to emerge.
• Evaluate the implications of sexual selection on the evolution of species and their adaptations to environmental changes.
  • The implications of sexual selection on evolution are profound, as it not only shapes individual traits but also influences the adaptive strategies of entire species. By prioritizing certain characteristics that enhance mate attraction, sexual selection can lead to rapid evolutionary changes that may or may not align with survival advantages in changing environments. For example, if environmental shifts favor different survival traits but mate preferences remain unchanged, species may struggle to adapt effectively. This tension illustrates how sexual selection can sometimes hinder or accelerate evolutionary responses to ecological pressures, impacting biodiversity and ecosystem dynamics.

Related terms

Mate choice: The process by which one sex selects a mate based on specific traits, often leading to sexual dimorphism and influencing genetic diversity.

Intrasexual selection: A type of sexual selection where individuals of the same sex compete for access to mates, often resulting in the evolution of traits that enhance competitive ability.

Sexual dimorphism: The differences in physical appearance between males and females of the same species, often driven by sexual selection.