SEXUAL SELECTION Flashcards
What is intersexual selection?
Intersexual selection occurs when individuals of one sex (usually females) choose mates based on specific traits, such as size, coloration, or display behaviors, leading to the evolution of those traits.
What is intrasexual selection?
Intrasexual selection occurs when individuals of the same sex (usually males) compete for access to mates, leading to the evolution of competitive traits.
What types of traits are selected in intrasexual selection?
Physical Traits: Size or weaponry.
Physiological Traits: Sperm production.
Behavior: Competitive behaviors that enhance mating success.
What is pre-copulation sexual selection?
Pre-copulation sexual selection is the process that occurs before mating, where individuals compete to attract mates through traits, behaviors, or resources.
What are the stages in pre-copulation selection?
Mate Competition: Competing with the same sex to show dominance.
Mate Choice: Females select mates based on desirable traits.
Signaling and Displays: Males perform visual or auditory displays to attract females.
What are secondary sexual characteristics?
Secondary sexual characteristics are noticeable differences between sexes that evolve to increase mating success, such as elaborate plumage or vocal displays in males.
What is post-copulation sexual selection?
Post-copulation sexual selection occurs after mating, where individuals compete to influence which sperm fertilizes the egg, shaping traits and behaviors to enhance reproductive success.
What are the processes involved in post-copulation sexual selection?
- Sperm Competition: Involves competition among sperm from different males to fertilize an egg.
- Cryptic Female Choice: Females can eject sperm or use hormonal signals to influence which sperm fertilizes their eggs.
What are epigamic characters?
Epigamic characters are traits selected for their role in attracting mates, including behaviors and ornamentation that signal fitness or genetic quality.
What are the reasons for mate choice?
Direct Benefits: Resources such as food, protection, or parental care.
Honest Signaling: Traits that signal indirect tangible benefits.
Fisher’s Runaway Sexual Selection: Exaggerated traits favored by females lead to a feedback loop enhancing the trait.
Sensory Bias: Preferences based on arbitrary traits linked to sensory systems.
What are the basic functions of sex?
Reproduction: Production of offspring.
Sex: Combining and mixing of genes through gamete fusion from different individuals.
How has reproduction evolved?
Asexual reproduction is the primitive state, while sexual reproduction evolved despite its costs, such as the two-fold cost of sex and reduced allele transmission in males.
Why do males and females often look and behave differently?
Differences arise from sexual selection, a subset of natural selection that describes the evolution of distinct male and female attributes based on their roles and pressures in mating success.
How do male and female gametes differ in terms of sexual selection?
Females: Few, large, and costly gametes, limiting their reproductive rate.
Males: Many, small, and inexpensive gametes, allowing them to seek multiple mating opportunities.
Q: How does parental investment affect sexual selection?
When parental investment is unequal, the sex with higher investment becomes choosy, while the sex with lower investment becomes competitive, leading to sexual selection dynamics.
