Sexual selection

Definition

Sexual selection is a mode of natural selection where certain traits increase an individual's chances of reproducing based on their attractiveness to potential mates. This concept plays a crucial role in evolution, as it drives the development of specific characteristics that can enhance mating success, such as bright plumage in birds or elaborate courtship behaviors. It highlights how not just survival but also reproductive success can shape the evolutionary path of a species.

5 Must Know Facts For Your Next Test

1. Sexual selection can lead to pronounced physical differences between males and females, known as sexual dimorphism, such as size or coloration.
2. Traits favored by sexual selection may not necessarily be beneficial for survival; in fact, they can sometimes increase vulnerability to predators.
3. Sexual selection operates through two main mechanisms: mate choice and intrasexual competition, both influencing the evolution of reproductive traits.
4. This form of selection can contribute to speciation by promoting divergence in traits between populations, leading to reproductive isolation.
5. Sexual selection can also explain the presence of seemingly maladaptive traits, such as extravagant tail feathers in peacocks, that evolve solely to attract mates.

Review Questions

• How does sexual selection differ from natural selection, and what implications does this difference have on evolutionary processes?
  • Sexual selection differs from natural selection in that it specifically focuses on reproductive success rather than survival. While natural selection promotes traits that enhance survival chances, sexual selection favors characteristics that make individuals more attractive to potential mates. This difference leads to the development of traits that may be detrimental for survival but advantageous for mating, highlighting the complexity of evolutionary processes and how they can lead to diverse adaptations within species.
• Discuss how sexual dimorphism arises through sexual selection and provide examples of species where this is evident.
  • Sexual dimorphism arises when sexual selection acts differently on males and females, leading to distinct physical characteristics. For example, male peacocks develop large, colorful tail feathers to attract females, while females tend to be more subdued in coloration for camouflage. In many species of birds, males may exhibit brighter plumage or elaborate songs compared to their female counterparts, directly correlating with mating success influenced by female preferences. This phenomenon illustrates how reproductive strategies shape physical traits within a species.
• Evaluate the role of sexual selection in driving speciation events and how it affects biodiversity within ecosystems.
  • Sexual selection plays a significant role in speciation by encouraging the divergence of traits that can lead to reproductive isolation between populations. For instance, when two groups develop distinct mating preferences or courtship displays influenced by sexual selection, they may stop interbreeding over time, ultimately resulting in the emergence of new species. This process increases biodiversity within ecosystems as different populations adapt to their environments and develop unique traits driven by their reproductive strategies. Additionally, it highlights how behavioral factors influence genetic variation and evolutionary trajectories.

Related terms

Mate choice: The process by which one sex, usually females, selects a partner based on specific traits or behaviors that indicate good genes or fitness.

Intrasexual competition: A form of sexual selection where individuals of the same sex compete for access to mates, often leading to the evolution of weapons or other competitive traits.

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