Sexual selection

Definition

Sexual selection is a natural selection process where certain traits increase an individual's chances of attracting mates and reproducing. This concept explains how certain characteristics, such as bright colors or elaborate displays, can evolve not for survival advantages but specifically for enhancing mating success. It is a key mechanism in the theory of evolution, illustrating how reproduction can shape species' physical and behavioral traits over time.

5 Must Know Facts For Your Next Test

1. Sexual selection can lead to the evolution of traits that may be detrimental to survival but advantageous for reproduction, like the peacock's tail.
2. It operates through two main mechanisms: intersexual selection, where one sex chooses mates based on certain traits, and intrasexual selection, where members of the same sex compete for access to mates.
3. Sexual selection can result in pronounced sexual dimorphism, where males and females exhibit different physical traits due to selective pressures associated with mating.
4. Species that experience intense sexual selection may exhibit elaborate courtship behaviors or displays that signal genetic fitness to potential mates.
5. Sexual selection can influence evolutionary pathways, leading to rapid changes in species' characteristics as they adapt to mating preferences and competition.

Review Questions

• How does sexual selection differ from natural selection in terms of its impact on species evolution?
  • Sexual selection focuses specifically on traits that improve an individual's chances of mating, while natural selection emphasizes traits that enhance survival and reproduction overall. For instance, a brightly colored male bird might attract more mates but also become more visible to predators, showcasing the trade-offs inherent in sexual selection. This distinction highlights how reproductive success can lead to the evolution of specific characteristics that may not necessarily contribute to an organism's survival.
• Discuss how sexual dimorphism arises from sexual selection and provide examples of species exhibiting this phenomenon.
  • Sexual dimorphism occurs when males and females of a species develop distinct physical traits due to sexual selection pressures. For example, male lions have impressive manes that signal strength and health, making them more attractive to females while also intimidating rivals. In contrast, female lions are less conspicuous and focused on hunting. This differentiation showcases how sexual selection shapes not just reproductive strategies but also the overall morphology of species.
• Evaluate the broader implications of sexual selection on biodiversity and ecosystem dynamics.
  • Sexual selection can significantly impact biodiversity by driving the evolution of diverse traits within species, leading to varied mating strategies and behaviors. These adaptations can affect population dynamics and interactions within ecosystems, influencing predator-prey relationships and resource allocation. As species evolve unique traits for attracting mates, this can lead to speciation events, contributing to greater biodiversity. The interplay between sexual selection and environmental factors ultimately shapes ecosystem resilience and adaptability.

Related terms

natural selection:

The process by which organisms better adapted to their environment tend to survive and produce more offspring.

mate choice: The process by which one sex selects a mate based on specific traits or characteristics that are often linked to fitness.

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