Paternal Care & Family Conflict

Question 1

What two factors determine which parent cares for the young?

Answer 1

1. Physiological / life history constraints
2. ecological conditions

Question 2

Example of parent care determination in birds

Answer 2

Success dependent on rate of foor delivered to nest –> repro. success increased by both parents staying

if food in excess: male deserts, female cares
- internal fertilization in female
- male lifetime success higher w/ more matings

Question 3

Example of parental care in fish

Answer 3

Usually only one parent cares, if any

• male in external fertilization, female in internal

Question 4

What 3 hypotheses describe the change in male/female care in external/internal fertilization?

Answer 4

1. paternity certainty
   - internal fert. involves sperm competition
   - external fert. is more certain –> male cares
2. order of gamete release
   - internal fert. lets male desert first
3. association
   - internal fert. sets stage for embryo retention, live birth, maternal care
   - external fert. lays eggs in the male’s territory

Question 5

What are the 2 tradeoffs in paternal investment?

Answer 5

1. offspring quality and quantity within brood
   - too many –> few survive
   - too few –> others have higher fitness
2. current vs future broods
   - increased investment now = lower investment later

Question 6

Examples of paternal investment tradeoffs (lizard, goby, beetle, bird)

Answer 6

side-blotched lizard females have trouble moving when carrying eggs

common gobies induced to put more effort into fanning eggs lose extra body mass and are more likely to abandon eggs

burying beetles with enlarged brood produce fewer future broods

collared flycatchers induced to increase feedings rate were less reproductively successful the next year

Question 7

Offspring quality vs parent condition

Answer 7

Higher quality offspring = present payoff
Higher quality parent = future payoff

Question 8

Example: offspring quality vs parent condition (New Zealand hihi)

Answer 8

-nestlings fed carotenoids had redder mouths (appear higher quality)
- unsupplemented parents fed supplemented offspring more
- supplemented parents did NOT feed supplemented offspring more

*supplemented parents more likely to lay a second clutch than non-supplemented

Question 9

Why is there filial cannibalism in fish?

Answer 9

fish use part of clutch as extra food to help attend the remaining clutch, or eat entire clutch if the best option is abandonment

ex. male scissor-tailed sergeant fish
–> allows male to return to mating phase sooner when clutch will not survive

Question 10

Example: female effort based on male quality (birds) *not proven

Answer 10

female zebra finches prefer bright red beaks

–> adding a red band to those males increased female chick-feeding effort (expectation of higher quality offspring)

Question 11

Conflict of interest in care

Answer 11

both would benefit most from the other parent providing all care

Question 12

Example of compensation (birds)

Answer 12

great tits - overcompensation
- begging call played to one parent
- both increased feeding
*this is stable

*assumed nestling need was constant, but that is not true

Question 13

Two types of familial conflict

Answer 13

1. intrabrood: parent-offspring and offspring-offspring r=0.5, self r=1.0
   * prefer excess for self

2.interbrood: parents care about future success, offspring care about present (themselves)

Question 14

Example: interbrood sibling rivalry (seal)

Answer 14

Fur seals
- females overproduce when environment is unpredictable
– max brood size in good years, siblings trim brood size in bad years (siblicide)
-produce 1 pup every 2 years, but wean at either 18 months or 2-3 years
– older pup more likely to survive

Question 15

Example: intrabrood sibling rivalry (bird)

Answer 15

blue-footed boobies
- female lays 2 eggs, incubates immediately after laying the first
– first is larger and more likely to survive due to that head-start
– younger only survives when food is abundant (insurance)

Question 16

What are the two types of siblicide?

Answer 16

1. Facultative
   - younger sibling killed / starved when food is scarce
   Ex. fur seal, blue-footed boobie
2. Obligate
   - mom lays 2 eggs, ONLY EVER fledges one chick
   – if first egg doesn’t hatch, second egg will survive
   Ex. Nazca boobies, American white pelicans, black eagle

Question 17

Example: parental effort (Coot)

Answer 17

• newborn chicks have bright orange tips on black body feathers
  – if 1/2 of brood is trimmed and other is not, feeding rate will drop for trimmed

BUT mortality rates of younger chicks equalize after 10 days
- first 10 days: chicks fend for selves
- after 10: each parent picks one of the smallest surviving chicks and overfeeds