Mating Systems II Flashcards
Mating systems with male parental care (monogamy, polygyny, conflict, polyandry threshold, desertion, polyandry) (18 cards)
Why does male parental care affect female dispersion?
Males become a resource
What are the two general patterns of monogamy? An example of each?
- Obligate monogamy (two parents are critical) - oystercatchers (higher survival the longer they’re together)
- Constrained monogamy (one parent CAN rear by itself, but two is highly preferred, but because CAN, male may have extra matings) - song sparrow (remove male = decrease success by 51%)
What are the three reasons males don’t just have multiple matings in a constrained monogamy? What is an example of the second reason (aggression)? What happens to a male’s primary offspring if he is polygynous? What is an example of the third reason?
- Strong competition between males = harder to attract female, females lose by sharing so may be aggressive to other females, female aggression towards male himself
- Pied flycatchers, male only helps at primary brood : primary does better than secondary and both are worse than monogamous (female perspective)
- His kids are more likely to be polygynous.
- Burying beetles - male helps feed young on carcass. When he displays for second female, the first will mount him and push/bite him to prevent him from doing this
What are two counters that monogamous males have against female extra pair copulations? What is a species example of each?
- Mate guarding (male cichlids)
- Swamping rival sperm by mating a bunch (osprey)
What is polygyny? What causes this in birds? What is the driver of polygyny?
- Multiple females per male
- Males monopolize females indirectly by guarding resources
- Cost/benefit to FEMALE (not male)
Under what circumstance is the cost of polygyny small/nonexistent? What is an example? Explain.
- Males don’t feed very much (little parental care) and habitat is high quality
- Yellow-rumped cacique - nest in trees by wasps (helps chase away preds = plus!)
Under what circumstance is there a cost to polygyny? What are two reasons females accept polygyny anyway? What is the polygyny threshold model?
- Sharing resources that the male controls (food/nest site) or loss of male parental care
- Limited bachelor males (marsh wrens) and territory quality is highly variable (take a larger risk if you don’t take a good territory while you can)
- There is a threshold territory quality of a male, below this quality females should be polygynous (because fitness is higher in poly than mono)
What is an example of a test of the polygyny threshold model? Elaborate. What was found in this group? What does this imply? What was found about the fledglings of polygynous and monogamous birds?
- Great reed warblers - they visit 3-11 males before nesting (some males help at nest).
- Some females went poly even when single males were available
- Implies that if the male territory is too low, she’ll just go ahead and be poly at a better territory
- Equally successful for females who settled at the same time (time is important because higher quality territories go away first)
What is another example (not the great-weed warbler) of the polygyny threshold model? Elaborate. What experiment was done with these birds? What were the results? What is the bottom line of this?
- Red-winged blackbirds - males defend territories and some females are polygynous, some monogamous
- Make one bigamous and one monogamous territory for each pair.
- Bigamous = fared worse (less young) because of predation and mono = higher feeding rates (dad helps with feeding).
- There is a cost to polygyny
What experiment was done to test whether females choose a high quality bigamy over low-quality monogamy? What was its result?
- 16 pairs of territories for males (1 retained a female and was enhanced, 2 was not enhanced no chicken wire)
- Found that 12/16 –> poly, 2/16 –> both, 2/16 –> mono
What is an implicit assumption about polygyny threshold model? What is a more common theme seen throughout species? What is an example of this more common theme? Elaborate. What was found about the young of the second female? What are the two reasons the second female –> poly?
- Females are free to do as they please and can gather information to make a decision
- Generally, there is a game between females, males, and males v females.
- Pied flycatchers - Males defend nest sites, mate, leave, try again, then leaves the second female for the first (full blown cheater).
- She has only 60% of young she could have had under mono
- Deception (male travels far and convinces her he’s single), and hard to find unmated males (limited choice)
What was an experiment done on pied flycatchers to demonstrate the sexual conflict and polygamy? What were its results? What did this demonstrate?
- Set up nest box some distance away from another nest box (for mated male) and also had an unmated male.
- Found 9/20 mated with unmated and 11/20 mated with taken males
- Female is unaware that the male has another nest waiting on him.
What is a second example of sexual conflict and polygamy (NOT pied flycatchers)? Elaborate. Under what conditions does the female do better? Under what conditions does the male do better? How does a female try to win this game (induce polyandry and prevent polygyny)? How does a male help prevent polyand?
- Dunnocks - express mono, polyand, polygyn, and polygynandry.
- Mono/polygynand (male helps) and polyand (2 males help)
- Polygyny (2 nests)
- Induce polyand by mating with two males before laying eggs (percentage copulations = percentage parental care) + prevent polygyn by chasing out subordinate female
- Mate guarding to limit copulation rate
What are three factors in dunnocks that affect the outcome of the game played between males and females for polygamy?
- Older males = more territorial and dominant (more likely to be polygyn)
- OSR can affect percentage of each mating system (females more likely to die in winter, and male biased OSR = polyandry)
- Territory quality/features with thick brush –> affairs because female can more easily escape mate guarding
What can cause polyandry in males (2 reasons)? What are two examples? Elaborate on each. Why are there no male squabbles in the second example?
- Food shortage (need two males to look for food), intense female competition (best of bad job)
- Lions (increase males = increase chance of winning the pride), normally with kin but may not be (because still better than being by yourself)
Galapagos Hawks (unrelated, share mating with single female and all contribute to childcare) (increase males = increase time holding territory/mating)
- No squabbles because females are larger than males so she can impose equal mating times
What is obligate polyandry?
Female has multiple males, and they all care for the offspring.
What is an example of mate desertion? Elaborate. What does desertion depend on (2 things)? What was an experiment done to test this and what were the results? Which sex is more likely to desert?
- Florida snail kites - Either sex may desert
- Chance of gaining another mate, and chance that one parent is enough
- Manipulate brood size (1-4 chicks), found that 1p/1o, 2p/2o (half the time one deserts), and half the time 3 doesn’t survive, and they cannot rear 4
- Female
What is an example of polyandry where sex roles are reversed (sequential polyandry)? Elaborate. What is a second example (resource defense polyandry)? Elaborate. Why would each species evolve polyandry?
- Phalaropes - female defends one male, lays a clutch, then leaves to find another (sequential polyandry) (female = bigger/brightly colored)
- Spotted sandpiper - females compete to defend territory with many males incubating eggs and tending young (resource defense polyandry)
- Spotted sandpipers breed in the tundra (food productivity REALLY high during breeding season, so she can just make em and go without worrying about energy constraints)
**Bonus: Jacanas breed in the tropics so increased predation risk so she will replace eggs that are killed (so polyandry)
