Sexual Selection Flashcards
Examples in nature?
Bright colours, weaponry, genitalia
Example of a banana skin?
Stegosaurs - plates along back have no apparent function, inappropriate to just assume it is sexual
Types? (2)
Pre- and post-copulatory
Pre-copulatory?
Intra-sexual i.e. same sex competition for a mate
Inter-sexual i.e. mate choice
Post-copulatory?
Intra-sexual = sperm competition Inter-sexual = cryptic female mate choice
What reproductive costs to males and females have? How does this affect mating systems?
Females (mostly) have more costly reproductive structures e.g. eggs
Males less so, more adaptive to mate as much as possible
What indicates sexual selection is at work?
Strong reproductive skew in males
How do males compete? (3)
Aggression i.e. fighting
Attraction such as dances
Increased reproductive fitness
Direct fitness benefits from female choice? (2)
Oral gifts e.g. food
Seminal gifts e.g. sperm provides nutrients
Evolution of female choice?
Sexy son hypothesis
Zahavi’s handicap principle
Sexy son hypothesis?
Choose males based on optimum traits for offspring success
Handicap principle?
Cost incurred by sexual traits mean they are an honest signal or male success
Post-copulatory examples in males?
(All intra)
Mate guarding
Removing rival sperm
Increased sperm production
Post-copulatory in females?
Cryptic female choice: Manipulation of sperm e.g. ejection/retention
Provisioning of offspring - resources biased towards those with best chance of survival
