Parental Care and Family Conflict I

Question 1

What does parental care look like in invertebrates? Why? What are a couple of example of species that tend to the eggs and species that tend to their young?

Answer 1

1. Mostly none
2. Can’t effectively protect young (like against a bird lol)
3. Eggs: bugs/female spiders. Young: beetles/roaches/leeches

Question 2

What sex mostly cares for young in fish? Mammals? Birds? Name one species example for each.

Answer 2

1. Males - stickleback
2. Females - meerkat
3. Both - blue footed boobies

Question 3

What are the two reasons variations in who cares for young (which sex) exist?

Answer 3

1. Physiological/life history
2. Ecological conditions/mating opportunities

Question 4

Why do both male and female birds care for young (what factor determines this)? What happens if this constraint is lifted? Which sex typically does this and why (2 reasons)?

Answer 4

1. Food - 2 parents can feed young twice as much
2. One will desert
3. males - 1) female has to hold fertilized egg, 2) increased mating is more valuable for males than females

Question 5

What does parental care look like for each sex in mammals? What are three reasons female mammals are more predisposed for childcare than other taxa?

Answer 5

1. Females care for kids, male takes extra matings
2. 1) Prolonged gestation, 2) lactation 3) internal fertilization

Question 6

In mammals, what are two behaviors that the male does to contribute to care? What is an example of each?

Answer 6

1. Feeding (cheetahs/carnivores) and carrying young (marmosets)

Question 7

What does parental care look like in fish? What are the two forms of parental care?

Answer 7

1. Most bony fish = no care, but some have care.
2. Guarding or fanning eggs

Question 7

What are the three reasons for the dichotomy in who cares for young in fish given either external or internal fertilization? Explain each.

Answer 7

1. Paternity certainty - external fertilization means dad can see that he is dad (whereas sperm comp. means he doesn’t know)
2. Order of gamete release - internal gives male a chance to desert first (external at the same time)
3. Association with embryos - internal = more embryo care = more inclined to maternal care. External = males defend territory and mate with multiple males so he ends up defending his eggs

Question 7

What is parental investment? What are it’s two scales of tradeoff and explain each?

Answer 7

1. Investment by parents in an individual offspring that increases the offspring’s chance of survival (and reproductive success) at the cost of the parent’s ability to invest in other offspring.

a. Between offspring quality and quantity (too many = few survive, too few = other parents have higher fitness)

b. Current vs future broods (increased investment may reduce future ability to invest)

Question 8

What are four examples of the cost of parental investment? Explain each.

Answer 8

1. Side blotched lizards - stomach too large when carrying eggs (limits leg movement)
2. Common gobies - lose body mass when fanning eggs and more likely to abandon them
3. Burying beetles - larger brood now = decreased # of future broods
4. Collared flycatchers - increase feeding rate –> lower fecundity the next year

Question 9

How do North American birds differ in their responses compared to South American birds when met with a nest predator? An adult predator? Why is this?

Answer 9

1. NA birds: stronger response against nest predator
2. SA birds have stronger response against adult predator
3. Larger clutch sizes and low adult survivorship make it so that the NA birds don’t care if they live as much as their nestlings. SA birds have constant food and small clutches, leading to wanting to keep themselves alive to have another clutch.

Question 10

What is a general idea about bird (parent AND offspring) quality and payoffs? How can you tell quality of offspring? What is example? What experiment was done on this example? What were the results? What is the reasoning thought to be behind these results?

Answer 10

1. Higher quality offspring –> increase present payoff

Higher quality parent –> increase future payoff for future reproduction

2. Yellow/orange mouths (carotenoids)
3. New Zealand hihi
4. Fed nestlings extra carotenoids, fed parents extra, or both.
5. Unsupplemented parents fed supplemented offspring more, no effect if parents were “of same quality” (also supplemented)
6. Supplemented adults more likely to lay another clutch, so they pay attention to the current brood quality.

Question 11

What is the motivation behind filial cannibalism (cannibalism by parents)? What is the parent really doing? What is an example of filial cannibalism?

Answer 11

1. Extra food to help it attend to rest of clutch or abandon
2. Increasing the fitness of the rest of the clutch or increasing her own fitness by taking relative stock of her future reproductive success
3. Male scissor-tailed sergeant fish - take away 75% of eggs, he will eat the rest because his clutch is small BUT wait three days to take them and he’ll keep them because parental cost (guarding) is low (closer to hatching) AND if given food, he won’t eat eggs.

Question 12

What is an example of parental investment by the female being determined by the quality of the male? What is the caveat to this conclusion?

Answer 12

1. Female zebra finches - adding red bands on legs = more attractive males = increase chick feeding when mated with red banded males
2. It was proven false later on (as negative results were under-reported)