3 - Sexual Selection Flashcards
What is:
- Sexual selection?
- intrasexual selection?
- Intersexual selection?
Sexual selection: selection for traits concerned with increasing mating success
Intrasexual selection: Selection on traits used to compete with members of one sex for access to the other sex (eg. antlers)
Intersexual selection: selection on traits used to attract the opposite sex (eg. plumage)
In intrasexual selection, what are some traits that have to do with competition for access to females? (5)
- Access to females (better able to contest each other)
- Access to resources (increasing reproductive success by attracting females, territoriality)
- Mate guarding (prevent female from mating with other males)
- Sperm competition (eg. more sperm)
- Copulatory plugs (eg. plugging females and other males so that sperm can’t be transfered)
What do females gain from intersexual selection? (3 direct benefits, 3 indirect benefits)
Direct (non-genetic)
- Feeding/support from male
- Parental care
- good resources
Indirect benefits (genetic)
- Good genes (handicaps and indices insure this is honest)
- Fisher’s runaway selection
- Chase-away sexual selection (arms race between female resistance and male traits)
Why do many animals have traits that seem ridiculous from natural selection point of view?
You could tell a lot about these traits from the behaviour of the animal.
Can often determine that they are for sexual selection or something like that.
What is Darwin’s theory of sexual selection?
Selection for traits that increase mating success
