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 development of traits that may enhance an individual's chances of attracting a mate, even if those traits might pose a risk in terms of survival. Sexual selection plays a critical role in shaping behaviors and physical traits among species, influencing mating preferences and strategies, as well as driving evolutionary changes over time.

5 Must Know Facts For Your Next Test

1. Sexual selection can result in sexual dimorphism, where males and females of a species exhibit different physical characteristics due to differing reproductive strategies.
2. Traits favored by sexual selection can sometimes be detrimental to survival; for instance, bright plumage in males may attract predators even while attracting females.
3. Females often choose mates based on traits that indicate good genes or high fitness levels, such as strength, health, or attractiveness.
4. The concept of sexual selection was first introduced by Charles Darwin in his work 'The Descent of Man', where he explained how mate choice influences evolution.
5. Sexual selection can lead to the evolution of elaborate courtship rituals and displays, which serve as important signals during the mating process.

Review Questions

• How does sexual selection influence physical characteristics in different species?
  • Sexual selection drives the evolution of distinct physical traits through mate preferences, leading to pronounced differences between males and females, known as sexual dimorphism. For example, male peacocks develop extravagant tails because females prefer mates with larger and more colorful displays. This preference results in evolutionary pressures that favor the development of these traits over generations, even if they come at a cost to survival.
• Discuss the role of female mate choice in sexual selection and how it impacts male traits.
  • Female mate choice is a critical component of sexual selection, where females select males based on specific traits that signal genetic quality or fitness. This selective pressure often results in males evolving extravagant characteristics or behaviors designed to attract females. For instance, males might develop brighter colors, elaborate courtship displays, or increased aggression to compete for female attention, ultimately shaping the population's genetic landscape.
• Evaluate the implications of sexual selection on species evolution in terms of both survival and reproductive success.
  • Sexual selection significantly impacts species evolution by promoting traits that enhance reproductive success, even if these traits may reduce individual survival. For example, while elaborate displays might make males more attractive to females, they can also increase visibility to predators. The balance between attracting mates and avoiding danger creates a complex evolutionary dynamic, illustrating how sexual selection shapes not just physical attributes but also behaviors crucial for survival within fluctuating environments.

Related terms

Mate choice: The selection of a partner based on specific traits, behaviors, or characteristics that may indicate genetic fitness or suitability for reproduction.

Intersexual competition: The competition between individuals of one sex to attract mates from the opposite sex, often leading to the development of elaborate traits or displays.

Intrasexual competition: Competition among individuals of the same sex for access to mates, which can result in physical confrontations or the display of dominance.