Chapter 11: Parental Care

Question 1

Key evolutionary force to sibling fighting

Answer 1

guaranteed access to resources. Some fight to kill, others fight to establish dominance so when resources are limited, they get first pick.

Question 2

obligate siblicide

Answer 2

two eggs are laid, only one will survive.

Question 3

Explain obligate siblicide in Nazca boobies. What kind of battle do they engage in? why?

Answer 3

In Nazca boobies, the eldest born sibling almost always kills the marginal/second born chick. There is a size assymmetry among the offspring even though they are hatched only days apart, giving the eldest born a huge advantage. Called a Cain and Abel battle.

Question 4

in species that engage in obligate siblicide, what is the point of laying a second egg anyway?

Answer 4

“insurance policy” if the first one fails to hatch. There is a 20% failure rate. Parents are creating the conditions for infanticide.

Question 5

How do sora and coot chickes indicate quality to parents?

Answer 5

Sora and coot chicks hatch with bright colored pumage to indicate quality to the parents. Parents favor the more orange chick. Indicates high reproductive value.

Question 6

parents prefer to invest in offspring with :

Answer 6

greater reproductive value

Question 7

Reproductive value is a measure of:

Answer 7

potential of an individual to leave surviving descendants in the future. Offspring with high RV are likely to go on to be successful breeders, whereas those with low RV are unlikely to reproduce much, if at all, during their lifetimes

Question 8

If resources are limited, how do parents decide which offspring to feed?

Answer 8

they provide resources to the children with high reproductive value.

Question 9

name the two hypotheses to explain how offspring signal to parents or other caregivers

Answer 9

1. SIGNAL OF NEED HYPOTHESIS
2. SIGNAL OF QUALITY HYPOTHESIS “I’m a high quality off spring and I need to be nourished so I can maintain my high quality”

Question 10

explain the signal of need hypothesis.

Answer 10

offspring signal to their parents the level of need in order to maximize their chances of being fed by their parents.

ex/ in birds, the red patch in mouth gets redder depending on hunger level. This can also signal quality though.

Question 11

explain the signal of quality hypothesis.

Answer 11

Signal’s that advertise an offspring’s QUALITY or merit in order to maximize their chance of being fed by their parents

Question 12

Explain how nestling barn swallows convey quality to their parents.

Answer 12

The colour of the mouth gape affects the amount of food that nestling barn swallows are fed by their parents.

Parents preferentially fed chicks with artificially reddened gapes. Gape colour may signal healthy chicks with high reproductive value.

Question 13

Explain the effects of orange plumage in baby coots and the effects of trimming the orange plumage.

Answer 13

Control groups composed entirely of either unaltered (orange) chicks or chicks that had their orange tips trimmed from their ornamental feathers (black) were fed at the same mean rate. In broods in which half the chicks were orange, and half were black, orange chicks were fed more.

Parents didn’t prefer all-orange to all-black broods. Orange chicks were only preferred if they had black siblings.

perhaps the CONTRAST indicates quality.

Question 14

explain discriminating parental care by buying beetles.

Answer 14

When mother is present, older siblings are fed more than when mothers are absent. There is no difference for junior siblings whether mother is present or absent.

therefore, female burying beetles prefer to take care of the eldest sibling.

Question 15

T/F: in sexually dimorphic species, female and male children have different costs to raise

Answer 15

true.

Question 16

Explain how red mason bees ADJUST investment to different offspring

Answer 16

Preferential gender treatment of children is dependent on the PHYSIOLOGICAL CONDITION of the parents.

when provisioning efficiency is high, the parents invest more in the females because they are more expensive. When the provisioninig efficiency (health) of parent is low, the males are invested in because they are cheaper to maintain

Question 17

Fisherian sex ratio

Answer 17

parents should invest equally in sons and daughters, and if they are equally costly, the equilibrium ratio should be 1 to 1. However, tehre are cases where the population sex ratio DEVIATES from this 1:1 fisherian sexratio.

Question 18

2 hypothesis that explains why population sex ratios deviate from the fisherian ratio

Answer 18

1) local competition hypothesis

2) local enhancement hypothesis

Question 19

explain the local competition hypothesis to explain Fisherian sex ratio deviation. Example.

Answer 19

When related individuals compete for resources or mates, then one sex is more costly to produce

In parasitoid wasps: they can control the sex of the offspring. They try and produce more females because it would give more grandchildren. (males would compete with each other)
- A 50;50 level is what is obtained when the both genders are competing to gain access to the opposite sex. Local mate competition can lead to deviation from the fisherian ratio.

Question 20

explain the local enhancement hypothesis to explain fisherian sex ratio deviation. example

Answer 20

When one sex provides more resources or enhances the mating success of its relatives, then that sex is cheaper to produce

Social insects: there are female biased sex ratios because the females are of more help to the colony (in bees/ants/wasps). Males don’t help out in the colony at all.

Question 21

Trivers- Willard hypothesis

Answer 21

Mothers adjust offspring sex ratio according to their own body condition, overproducing the sex with higher variance (MALES) in reproductive success when in good condition; investing in the sex with low variance (FEMALES) when in poor condition

Generally; its males with a higher variance in mating success.
If you are in bad condition, there is no use making the higher variance sex because there is a high chance that you will produce a poor quality son. It’s better to produce a daughter, because they have a low-variance reproductive success rate; they almost always reproduce.

Question 22

T/F: Women with access to better food resources are slightly more likely to have sons than women with less to eat

Answer 22

TRUE.

Question 23

In egrets, sibling aggression is common. How do parents facilitate aggession?

Answer 23

The aggression is condoned by parents who stand by and do not interfere in sibling aggression. Parents orchestrate the outcome by creating competitive asymmetries among the offspring via hatching asynchrony.

Question 24

what is the parent offspring conflict

Answer 24

some actions can advance the fitness of an offspring while reducing the reproductive success of its parent.

offspring should behave more selfishly than parents desire.

Question 25

T/F: if there are enough resources, species that practice obligate siblicide will spare the youngest.

Answer 25

False. Siblicide will ALWAYS occur, regardless of food supplies, ecological conditions, or brood size.

ex/brown and Nazca boobies, black eagles, white pelicans.

Question 26

Insurance hypothesis.

Answer 26

Mothers in siblicidal species lay a second egg as insurance against hatching failure

Black eagles are obligately siblicidal: when parents lay two eggs and both eggs hatch, the elder nestling typically murders the younger sibling shortly after the second chick hatches. Parents do not intend to rear both chicks, but create the second egg primarily as insurance against the first egg failing to hatch.

Question 27

Facultative Siblicide and examples

Answer 27

FACULTATIVE SIBLICIDE: aggressive brood reduction that is conditional upon current ecological conditions including food supplies or brood size.

if there is a surplus of food, the younger osprey will be spared.

ex/ Ospreys, blue footed boobies.

Question 28

Explain parental influence on siblicide

Answer 28

The rate of early siblicide by Nazca boobies (NB) declines when they are placed in nests with intervention-prone Blue-footed booby (BFB) foster parents– the foster parents will try and stop the siblicidal nazca boobies from killing each other.
Conversely, the rate of early siblicide by BFB chicks rises when they are given Nazca booby foster parents.

Question 29

Facultative siblicide hypothesis.

Answer 29

Parents permit siblicidal behaviour only when resource availability is low

Question 30

What is an index of parental efficiency

Answer 30

the number of surviving chicks divided by the volume of food brought to the nest per day x 100

Question 31

When is parental efficiency highest in egrets? (obligative siblicide)

Answer 31

The fewest chicks survived in the synchronous broods (no chick had an advantage over the other). Normal asynchronous broods provided the highest parental efficiency.

Question 32

What is facultative brood reduction?

Answer 32

methods of reducing brood in a non-aggressive manner. ex/ chicks in red winged blackbirds that are born later often face starvation.

Question 33

explain facultative brood reduction in red winged blackbirds

Answer 33

Mothers can control when their chicks hatch by controlling incubation. If incubation occurs before all the eggs are layed, then there will be a time difference between which eggs hatch in the nest. The core group of chicks will survive, and the marginal group often does not because it is the last hatched off spring. Core offspring has higher reproductive value and often has a 90% survival rate. Parents create marginal group (60% success rate). The most junior egg of the marginal group (aka the youngest in the nest) has a survival rate of 11%.

Question 34

In facultative brood reduction, what is the point of producing marginal offspring?

Answer 34

1. Extra reproductive value (resource tracking hypothesis) if there is enough food, they may survive. Aka Parental optimism; its easier to create a bunch and then wean down.
2. Insurance; if one “core” fails to hatch, one of the marginal eggs gets bumped up to core level.
3. Facilitation hypothesis – e.g., by serving as food for other family members. Ex/ icebox hypothesis; the food stays “fresh” until you eat it. Ex/ group heterothermy; the younger chicks serve as insulation for the older chicks

Question 35

Describe the asymmetric sibling rivalry seen in species that practice facultative brood reduction

Answer 35

Adding or subtracting marginal offspring has no effect on the core offspring, but taking off core offspring affects the survival or marginal offspring. Therefore, adding lots of marginal offspring is “cheap insurance” because your core chicks won’t be affected.

Question 36

largest cost to providing parent care

Answer 36

the fact that investing more in the current brood may mean reduced investment in FUTURE BROODS.

Question 37

What is the relationship between parental care and adult life span? Example?

Answer 37

adults with a shorter lifespan are more likely to take care of offspring, but longer lived organisms are predicted to do more to promote their OWN SURVIVAL.

ex/ north american birds have shorter lifespans are more likely to stick around the nest if there is a NEST predator nearby. South american birds are more likely to go on feeding trips away from their nest if a NEST PREDATOR IS NEARBY, because they live longer and are more sensitive to risks to THEMSELVES.

The south american birds will stick around the nest if an ADULT predator is nearby.

Question 38

Matriphagy

Answer 38

moms get eaten by their kdis.

Question 39

explain matriphagy in caecilians

Answer 39

Mother caecilians live with their offspring and permit them to remove and feed upon their nutritious skin.
Nestling caecilians have curved teeth for the very purpose of stripping edible skin from their mothers.

Question 40

why do females exert more parental care?

Answer 40

One explanation for the pattern is that because females already have so much invested in their progeny, they have a greater incentive to see that their investment is not wasted.

Question 41

explain the counter intuitive phenomena regarding parental care in sandpipers

Answer 41

In most species, females pay more parental care. However, in the spotted sandpiper, females drop their eggs off with the males and leave.Males raising the kids: Shore bird females fight for males. Then the male incubates the egg and protects the egg.

Question 42

explain paternal care in male jawfish.

Answer 42

A male Randall’s jawfish holds his mates eggs in his mouth. Mouth brooding limits a male to one clutch at a time. In jawfish, males are reproductively limited by taking care of young.

Question 43

explain paternal care in male sticklebacks.

Answer 43

carotinoids in the skin signal the ability of them to fan eggs and take care of them. Female lays eggs in the nest and even though the male is spending time fanning the eggs, he actually attracts other female fish to laying eggs. Therefore, males do not lose reproductive chances by fanning eggs. If he truly starts to lose condition, he can snack on some of the larvae (the ones that are the most recently laid)

in sticklebacks, males do not lose reproductive chances by fanning eggs. He actually attracts others.

Question 44

In earwigs, females protect broods until the kids have developed. Therefore, parental care and brood protection takes longer and extends the ____ ____

Answer 44

interclutch interval.

Question 45

When are males more liekly to provide parental care?

Answer 45

when they are certain to be fathers of the offspring.

Question 46

T/F: In species with internal fertilization, males are more likely to help take care of the offspring

Answer 46

TRUE.

Question 47

According to the paternal uncertainty hypothesis:

Answer 47

males do not take care of offspring as much because it is possible that it is not their kid.

Question 48

In fish, males are more likely to care for offspring if:

Answer 48

there are not many males in the area and he knows that he most likely fertilized the female.

Question 49

males are often torn between parental care and seeking extra mating opportunities. When is this trade off reduced?

Answer 49

But this trade-off is much reduced in mating systems in which females are drawn to egg-guarding, parentally committed males.

Question 50

Explain the costs of care in mouth brooding cichlids.

Answer 50

in cichlids/st. peters dish, either males or females may mouthbrood the clutch. Both sexes thus lose weight when mouthbrooding.

Both sexes must replenish food reserves after brooding, but females must wait longer

Question 51

In cichlids, why does parental care cost MORE FOR FEMALES than MALES?

Answer 51

1) Females that have cared for their eggs are much slower to produce a new batch of eggs than females that have not provided care to their previous clutch
2) Males have a lower interspawn interval than females in general, therefore, they can spawn sooner after taking care of eggs. It should lend itself well to making males take care of the eggs

(But, nonparental males have the fastest interspawn interval)

Question 52

In water bugs, why do males provide all the parental care?

Answer 52

Male water bugs with one clutch of eggs can CONTINUE TO ADVERTISE for more females: this may even be attractive, advertising his ABILITY to take care of the kids
The costs of care may also be greater for females than males given the high cost of egg production

Also, waterbug eggs are really large and the females are often so exhausted making these eggs on land. They are thus not involved in maternal care.

Most aquatic insects lay smaller eggs in water but the larger the adult, the larger the egg is required to incubate the insect.
- They need to be laid outside of water. Therefore, the males moisten the eggs while they are out of water in order for the offspring to be larger.
But belostomids solve the problem by laying eggs out of water
This raises another problem: drying out (males keep the eggs moist)

Question 53

Discriminating parental care

Answer 53

parents often take better care of offspring that are genetically theirs.

Question 54

Explain discriminating parental care in bats

Answer 54

Despite the fact that they leave their infants in a dense mass of baby bats when they leave their caves to forage outside, when a female returns to nurse her pup, she can relocate her son or daughter among thousands of individuals.

Question 55

What is the difference between discriminating parental care in colonial or isolated species? (ex/ cliff swallows vs barn swallows)

Answer 55

The chicks of cliff swallows, a colonial species, produce highly structured and distinctive calls, helping their parents recognize them as individuals.

The calls of barn swallow chicks, a less colonial species, are much LESS STRUCTURED and more similar (they know which kid is theirs because their nest is more isolated)

Question 56

If parents often take care of genetically-related offspring better, why do some chicks seek adoptive parents?

Answer 56

third-hatched chicks in gull nests may not receive enough food in their current nest. They may try and “run away” and find another nest in which they are older than the other chicks. It is a HIGH RISK strategy though, because adults of the other nests may attack and kill the strange chick trying to add themselves to the nest.

If they are adopted however, they tend to weigh more than the third-born in a genetically related nest. Sometimes this strategy pays off.

Question 57

What is interspecific brood parasitism?

Answer 57

Interspecific brood parasites can insert themselves into a family of a COMPLETELY DIFFERENT SPECIES by employing deceptive signals that trigger parental care by their hosts

Question 58

What kind of parasitism is employed by european cuckoos?

Answer 58

Engages in interspecific brood parasitism. The European cuckoo chick’s begging call matches that of four baby reed warblers.

Cuckoo chicks can make calls that sound like 4 reed warbler chicks. Therefore, they get fed the same amount as 4 warbler chicks. They need this amount of food in order to grow because they are so large. They also kick out all other baby chicks who are in the nest with them.

Question 59

What kind of parasitism is employed by cowbirds?

Answer 59

interspecific brood parasitism.

Cowbird eggs get laid in a red winged black bird nest and then they are taken care by red winged black bird parents. Cowbirds do not mimick eggs, they just rely on the fact that newly hatched chicks look similar. Cowbirds are non-specific parasites; they’ll parasitize different breeds of other birds.

Question 60

Why don’t host parents just throw out a parasite’s egg?

Answer 60

1) recognition error: there is a risk that you’d toss out your own egg. this is very costly.

2) Mafia hypothesis: Hosts accept brood parasitic eggs out of fear of retaliation by the brood parasite for destroying its eggs
Evidence:
European magpie nests from which great spotted cuckoo eggs had been ejected suffered significantly higher predation than nests with accepted cuckoo eggs (87% vs 12%). If adults of the victim nest remove the parasite eggs, then the parasite parents will destroy the other eggs of the victim’s nest.

Question 61

T/F Cowbirds are mafia species.

Answer 61

true. Cowbirds are among the brood parasitic birds that may punish hosts that fail to incubate the parasite’s egg

Question 62

what is avian vandalism in cowbirds

Answer 62

The earlier that cowbirds hatch relative to victim offpsring, the better. If the victim is already incubating eggs, it’s too late for the cowbird to lay. The cowbird tries to destroy the incubating eggs and the nest, forcing the blackbirds to “start again,” and then the cowbirds parasitize the new nest which are just built.

Question 63

Intraspecific brood parasitism

Answer 63

Some brood parasites are specialists that lay their eggs in the nest of only a single host species

Question 64

Cowbird lay their eggs in nests where they know that their young will be ____ than the victim nestlings

Answer 64

LARGER. The cowbird also has a faster incubation rate than the host nestlings, therefore, they will be the first to hatch and will thus be safe from the core/marginal nestling group dynamics. Host generalists must place their eggs in situations where they can succeed.

Question 65

Why won’t cowbird babies eject/fight with its host nest mates?

Answer 65

it needs its host mates to call for food, the cowbird babies have a different call that is not heart by the red wing black bird parents.

Question 66

What is a “coevolutionary arms race”

Answer 66

Whenever there are two parties in conflict with each other, as there are in the case of a brood parasite and its host, the two sides exert reciprocal selection pressure on each other, with an adaptive advance made by one often leading eventually to an adaptive counter-response by the other

Question 67

example of a coevolutionary arms race against brood parasitism

Answer 67

Chicks of Horsfield’s bronze cuckoo, a specialist brood parasite on fairy wrens, MIMIC the fairy wren nestling call.
The Shining bronze cuckoo nestlings rarely parasitize fairy wrens, and do not mimic the calls of the fairy wrens, NOR do the nestlings look like fairy wren nestlings.

In order to recognize their own kids; fairy wrens in the eggs will listen to their parents contact call. When they hatch, they play out the contact call to their parents. Bronze-cuckoos do not record this contact call despite being in the fairy wren host nest. Acts as a lock and key mechanism to prevent parasitism in FAIRY WRENS.

Question 68

Conspecific brood parasitism

Answer 68

parasites targeted nesting adults of their own species

Question 69

Gradual shift hypothesis to brood parasitism

Answer 69

The evolution of intERspecific brood parasitism involved intRAspecific parasitism as an intermediate stage