BIOL 3445 Lecture Notes - Lecture 21: Nuptial Gift, Coevolution
BIOL 3445.001 | Lecture #21 | 4/3/2018
Sexual Selection and Mating Systems
OBJECTIVES
― Explain the differences between direct and indirect benefits of female choice
― What are the differences between “sexy son” and “good genes” hypotheses
― Why does selection for female preferences and male ornaments produce a
feedback loop?
― Why do sexual conflicts between males and females arise?
FEMALE CHOICE
Direct Benefits
― Females gain direct benefits by choosing males who provide a resource:
o Food/Nuptial gifts
o A good territory
o Protection from other males
o Less risk of STDs
o Help with the kids
― May males offer nuptial gifts to entice females to mate with them
o These may be food items or spermatophores (nutrients combined with
sperm)
o Females gain fitness advantage by accepting these gifts
― Sexual Cannibalism: an extreme form of nuptial gift where the male is eaten
during/after copulation
o Some males evolve defenses (very small size) to avoid being eaten
o Some have evolved behaviors to ensure that they are eaten
― EXAMPLE: Redback Spiders
o Males have very little chance of finding and mating with more than one
female
o They gain more fitness by allowing the female to eat them during mating
o This behavior prevents the female from mating again and provides
nutrients to her so her eggs will be higher in quality
find more resources at oneclass.com
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Document Summary
Explain the differences between direct and indirect benefits of female choice. What are the differences between sexy son and good genes hypotheses. Females gain direct benefits by choosing males who provide a resource: food/nuptial gifts, a good territory, protection from other males, less risk of stds, help with the kids. May males offer nuptial gifts to entice females to mate with them: these may be food items or spermatophores (nutrients combined with sperm, females gain fitness advantage by accepting these gifts. Sexual cannibalism: an extreme form of nuptial gift where the male is eaten during/after copulation: some males evolve defenses (very small size) to avoid being eaten, some have evolved behaviors to ensure that they are eaten. Sensory bias: innate preferences for certain visual/auditory cues drive the evolution of female preferences. Evolve according to the benefits that males and females experience.
