week 5 + 6 - family dynamics

Question 1

family dynamics
components

Answer 1

mother-offspring
father offspring
parents-offspring
- extended family: uncles/aunts/grandparents/cousins/Niblings –> non-kin members of the group

siblings (same generation)

siblings (different generation)

Question 2

parent-offspring conflict: how much aid to give?

Answer 2

Overlapping, but not identical, genetic interest: 0.5
Natural selection ill act to maximise the number of offspring an individual has over their lifetime
Each offspring is most important in their own eye = conflict
- How much aid to give current offspring and how long for?
o Further complicated if more than one offspring
- How much energy to save for future offspring?

Question 3

family dynamics
case study: primates

Answer 3

• Weaning conflict: Rhesus macaques are seasonal breeders – the previous years infant must be weaned to enable breeding to take place again
• Carrying conflict
• Temper tantrums

Question 4

evolution of begging

Answer 4

• Resolution to the conflict
• Assumptions:
  o Parents should respond with increased provision
  o Begging should be costly
  o Begging should vary in relation to need
   An honest signal
  e.g. red gape in birds- red will be strongest in birds that need feeding

Question 5

is begging reliable?

Answer 5

• Offspring signals do appear to vary with need
  o Vocal displays most common
  o Cardueline finches gape changes colour
• Parets do increase provisioning with signal intensity
  o Observed in passerines
  o Exception: seabirds
   E.g. manx shearwaters

Question 6

example of parent-offspring communication

Answer 6

humans
- newborn babies cry more if separated from mother –> mothers pick them up

pied-bill grebe
- loral colour becomes redder with increasing hunger –> parents feed chicks with redder loral areas

Question 7

sibling rivalry

Answer 7

Scenario A: abundant resources
Scenario B: limited resources

• Competing siblings can waste resoucres
  o Increases parent-offspring conflict
• Asynchronous birth
  o E.g. laying eggs a few days apart
  o Brood hierarchies

Question 8

insurance egg hypothesis

Answer 8

• 2nd egg is laid as insurance against infertility, but parent cant raise both to independence
• Surplus offspring removed of older one is viable
• Parents that produce two eggs have greater overall success than those which produce only one
• BUT is some species the second egg may be raised if the conditions allow it

Question 9

extended family

Answer 9

• Social learning and cultural transmission
  e.g. hapanses macaque

sweet potatoes provided by researchers
–> washed by one individual
–> passed on to other in the troop (social learning)
–> new infants learnt from their mother and others (cultural transmission)

Question 10

effect of living with others

Answer 10

• Social learning and/or cultural transmission
  o Learning directly for a model individual
• Local enhancement
  o Drawn to a particular environment by the action of another individual
• Social facilitation
  o Mere presence of another individual indices behavioural change
   E.g. feeding rate

Question 11

adoption
Why would animals ever adopt another animal that wasn’t a kin relation?

Answer 11

• Group size matters
• 25% of study packs contained non-breeders providing care for non-kin pups
• Costs = delayed (more competition for mates)
• Benefits = more individuals for territory defence, hunting etc and thus increased survival