Sexual Selection III Flashcards
Affairs, sexual conflict, male/female adaptations, chase-away selection (13 cards)
What are some common features in male birds that encourage females to accept affairs?
Many songs, long tail, brighter colors, large white forehead patches
How does the quality of the social mate affect affairs by females?
Low quality mate = more likely to have an affair (sorry lads)
What is a general trend about females and attractive males? What is an example? Is the male or female driving this?
- Females invest more when mating with an attractive male
- Mallard ducks: females lay larger eggs after affairs
- We dunno. Could be that mating extra leads to more investment or that affairs happen because females invest more. Who knows.
Explain Antechinus Australian marsupials. What makes them special? What is the consequence of this? What was an experiment done with them (four total groups)? What were the results? What is the bottom line from this example?
- They breed once then die after being reproductively active for two weeks. Both individuals multiply mate.
- No tradeoff because current and future success because there is no future (reduces nongenetic effects)
- Two groups: mate with same male, and mate with three different males. For each group: 1 yr in field and yr 2 in lab
- Results: Children more likely to survive in polyandrous mating and lab more likely to survive than the field.
- Bottom Line: Multiple mating makes it more likely for a female to have her offspring sired by good males via sperm competition.
What are the three reasons that a female wouldn’t just choose a high quality mate to begin with instead of having affairs? What is an example of one of the reasons?
- Intense competition for high quality male, reduction in parental care (if affair detected), choice limited by sexually antagonistic genes (choose social mate for daughter fitness, and affair for son fitness because daughter traits (such as big hips) are bad for sons but good for daughters)
- Example of reduction in parental care: Collared flycatchers will reduce effort in feeding if female is gone for 1hr during fertile period).
What is the sexual conflict problem? What does this cause?
- Males want to max. matings, and females want to maximize investment in offspring.
- Conflict between the sexes over mating
What is an example of sexual conflict over mating? What is a counter by the female in this example? What is another counter done by both the male and the female? What is this overall an example of?
- Water striders - males pounce on females, and she as a result is slower
- Females dip tip of her abdomen in water to throw off males
- Armor on both. For males its to help hold better, and on females it’s to keep males from getting on.
- Arms race
What are some male adaptations to sexual conflict (there are seven)? What is an example of each?
- Sperm movement - damselflies - have inflatable penis moving other flies’ sperm out of the way
- Sperm removal - damselflies - scoop penis that removes previous fly’s sperm
- Copulatory plugs - male spiders - cements the genital opening of the female so she cannot mate
- Plugs for rival male - worm - cements rival males to prevent him from mating
- Traumatic insemination - bed bug - pierce female’s abdomen and injects sperm into the body to swim to ovaries (can also do this to males so his sperm goes in instead of his)
- Anti-aphrodisiacs - Heliconius butterflies - bad smell he puts on females after mating
- Accessory gland proteins - fruit flies
What are the four functions of the accessory gland proteins that a male can insert into a female to keep her from mating with more males? What is a caveat to these proteins?
- Incapactiate rival male sperm
- Protect his own sperm from enzymatic attack
- Increase female’s egg laying rate
- Decrease chance that female remates
The proteins can reduce the female’s longevity which also keeps her from mating with more males.
What are some female adaptations to sexual conflict (there are two)? What is an example of each?
- Eject sperm - red jungle fowl will contract the walls of her cloaca to eject
- Choose which sperm - field crickets will use other sperm if she accidentally mates with a sibling
Which sex ultimately wins the sexual conflict issue? What experiment on drosophila illustrates this point? What were the results? What happened when monogamous females were mated with strong sexual selection males?
- Neither because each evolves adaptations to the other
- Experiment: 1 vial had 3 males + 1 female = sperm comp. in males and coping mechanisms for females
2 vial had 1 male + 1 female = no comp. and selection on male to maximize female lifetime
- Monogamous males showed decreased courtship, lower mating rate (increasing female survival and fecundity)
- Females = lower survival and reproductive success (less resistant than strong selection females)
What is chase-away sexual selection? What are two examples?
- Males selected to induce females to mate and females selected to resist male ploys
- Ducks: males = phallus that is longer if there’s more forced affairs, females = elaborate vaginal cavity to keep from mating
- Swordtails: platytailed females prefer swordtailed males BUT female swordtails prefer swordtails less than platytailed females do (chase-away selection on females)
What is a by-product benefit of the game between the sexes? What is an example?
- Parasites can win
- Mosquitos - males transfer a mating plug + 20E protein to females –> increased egg production + MISO + use plug to keep other males away –> MISO decreases immunity to malaria parasite
