BIO220 Lecture 3 Flashcards
Sexual selection & female choice
Mating behaviour of satin bowerbird
Males build bowers pre-mating season, and decorate with blue/yellow objects to attract females. Mate her while she is distracted with the decorations.
Mating behaviour of sage grouse
Leks: female come in to inspect the males, and pick one that she wants
How is the variance in sage grouse mating?
High variance in mating success in males (1 or 2 males get all the females)
Female choice
A female trait that biases the mating success of males towards the preferred type
Other words for female choice
mating bias, female preference
What categories of traits are the females looking for?
- Visual stimulation
- Tactile stimulation
- Acoustical stimulation
- Olfactory stimulation
Examples of organisms that use visual stimulation
Scorpionfly Barn swallow Long-tailed widowbird Satin bower bird Cichlid fish Field cricket Jungle fowl
Examples of organisms that use tactile stimulation
Sierra dome spider
Examples of organisms that use acoustical stimulation
Field cricket
Woodhouse’s toad
Great reed warbler
Tungara frog
Examples of organisms that use olfactory stimulation
Mouse
Cockroach
Moth
Why was the tail manipulation experiment done, and on what species?
To make sure the trait we think is being selected for by females is actually being selected for.
Done in widow birds.
What were the groups that were in the tail manipulation experiment
Natural (N)
Reduced (R)
Elongated (L)
Sham surgery (S)
What is the purpose of sham surgery?
Tail length not changed, but some manipulation is done (control group)
What was found by the tail manipulation experiment?
L > N = S > R
Females do prefer males with longer tails
What peacock trait do females prefer?
More eyespots on tail
Two animals which use visual stimulation to attract mates
- Widow birds
2. Peacocks
How do tungara frogs attract mates?
Complex calls (whine & chucks); Whines attract females, and number of chucks is what makes one male better than the other.
Why don’t all tungara frogs have more complex calls?
Bats are attracted to whines of males too, and they are more likely to get eaten if they have more chucks
Two problems of female choice
- Why are male elaborations common?
2. Why do females prefer certain traits?
Why are male elaborations common?
Females prefer them, so there is selection for elaboration
Why do females prefer certain traits in males?
- Direct benefit to female for selecting such traits (can produce more offspring)
- Indirect benefits to females (through offspring)
Direct benefit hypothesis implies that females select males w/ certain traits b/c
She’s actually selecting for resources (PI) that the male has. The trait is just an indicator of PI.
PI
Parental investment
How do female mormon crickets pick mates?
Pick those with bigger spermataphores. Male will stick it on her, and while she eats the protein, the sperm will fertilize her.
