Sexual selection

Definition

Sexual selection is a mode of natural selection where individuals with certain inherited characteristics are more likely than others to obtain mates. This process can lead to the evolution of traits that enhance an individual's chances of attracting a mate, even if these traits may not necessarily improve survival. It often results in pronounced differences between the sexes, influencing mating behaviors and preferences within species.

5 Must Know Facts For Your Next Test

1. Sexual selection can occur through two primary mechanisms: mate choice and competition among individuals of the same sex.
2. Traits favored by sexual selection may be costly in terms of survival, as they can make individuals more visible to predators or require additional energy to maintain.
3. Sexual selection can lead to elaborate courtship displays and secondary sexual characteristics, like bright plumage in birds or large antlers in male deer.
4. In some species, females may choose mates based on traits that signal genetic quality or health, ensuring better offspring survival.
5. Sexual selection is especially relevant in sympatric speciation, as it can drive divergence between populations that occupy the same habitat but develop distinct mating preferences.

Review Questions

• How does sexual selection contribute to the formation of distinct mating preferences within a species?
  • Sexual selection contributes to distinct mating preferences by favoring individuals that possess certain traits deemed attractive by potential mates. For example, females might prefer males with bright colors or elaborate displays, leading those traits to become more pronounced over generations. This process can create variations within the same species, as different populations develop unique preferences that promote reproductive isolation.
• Discuss the role of sexual dimorphism in understanding sexual selection and its impact on speciation processes.
  • Sexual dimorphism plays a crucial role in understanding sexual selection as it highlights the differences between males and females driven by their reproductive roles. These differences can include size, coloration, and behavior, often resulting from sexual selection pressures. In the context of speciation, pronounced sexual dimorphism can lead to isolated mating strategies within overlapping populations, contributing to reproductive isolation and ultimately driving sympatric speciation.
• Evaluate how sexual selection might influence genetic diversity within populations experiencing sympatric speciation.
  • Sexual selection influences genetic diversity within populations undergoing sympatric speciation by promoting divergent traits among individuals that are favored in mate choice. As different preferences emerge within a shared habitat, these selective pressures encourage variations in traits linked to mating success. This divergence not only creates distinct mating signals but also enhances genetic differentiation within populations over time, facilitating the development of new species.

Related terms

Mate choice: The process by which individuals select their partners based on specific traits or characteristics that are deemed desirable.

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

Intrasexual competition: Competition among members of the same sex for access to mates, which can influence the evolution of traits that provide advantages in these contests.