Flashcards in BIO220 Lecture 3 Deck (50):
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)
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
Satin bower bird
Examples of organisms that use tactile stimulation
Sierra dome spider
Examples of organisms that use acoustical stimulation
Great reed warbler
Examples of organisms that use olfactory stimulation
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
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
1. Widow birds
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
1. 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?
1. Direct benefit to female for selecting such traits (can produce more offspring)
2. 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.
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.
Sperm attached to a protein glob. Bigger = more protein for females to nourish herself with.
How do hanging flies pick mates?
Male kills prey, and displays to attract female with food. Females pick bigger offering. While she eats the food, male fertilizes her.
Why might bigger prey displays be beneficial to male and female hanging flies?
Females: more food
Males: have longer time to fertilize while female is eating = more sperm transferred
What do females look for as indicators of PI?
- Territory quality
- Parental care
- Lack of parasites (STIs)
Indirect benefit hypothesis implies that females select males w/ certain traits b/c
They have better genes so offspring will be better (fitness)
When is indirect benefit hypothesis applicable?
- Only thing male gives female is sperm
- Female want to improve offspring quality, not quantity
How to test indirect benefit hypothesis?
Female identifies preferred male trait. Mate her to ones with best trait and worst trait. Examine offspring.
how are sex roles defined?
Resource investment in the offspring
Examples of high male PI?
- Giant water bugs
- Spotted sand piper
Pipefish male reproductive success limited by...
size of their brood pouch
Pipefish female reproductive success limited by...
access to males' brood pouch
Mating system of pipefish
Females compete and are sexually selected for by the males
What do male pipefish look for?
Larger females (more eggs) & large fold
Katydid mating system (normal)
Males transfer spermataphores to female
Katydid mating system (low resources)
Females need male for spermataphores, and males limited by the resources to make spermataphores.
Males become the limiting factor.
Females will be sexually selected.
What changes when food is scarce for katydids?
- Male calls decrease
- Females mate more
- Male mate choice increases
- Female competition increases
Major histocompatibility complex
What does MHC do?
Code for antigen recognition system of the immune system
Loci that code for antigen recognition (immune response)
MHC in humans is...
What kind of MHC is good?
Ones with lots of genetic variation -> defend against more pathogens
Why do mice choose mates based on MHC?
- Avoid inbreeding
- Increase genetic diversity at MHC loci
Do mice choose mates based on MHC?
Yes; mate choice based on odours that correspond with differences at MHC loci
Are humans affected by odours that correspond with HLA?
What were the results of the odour study in humans?
- Intensity of odours similar between different HLA and same HLA group
- Women prefer those with different HLA