Sociobiology and behavioural ecology

Question 1

Evolutionary approach diff name

Answer 1

behavioural ecology - stresses the way that behavioural contribution to Darwinian fitness depends on ecology
sociobiology - Wilson’75 - a new synthesis, stresses merger behaviour and genetics
central behaviour - explanation of altrusim

Question 2

altruism

Answer 2

behaviour that increases survival and reproduction of other individuals at a cost to ones own s and r
eg. beldings ground squirrel alarm call to alert others there are predators around
= altrustic act as it helps others at a cost to self

Question 3

4 hypotheses for why altruism evolved?

Answer 3

kin selection
mutualism
manipulation
reciprocal altruism

Question 4

Kin selection (Maynard smith 1964) 
gene proliferation?
coefficeint of relatedness (r)?

Answer 4

relatives have copies of our genes we want to pass on = help kin to reproduce = pass on genes
-gene proliferaton - can occur through care for relatives –> acts may be phenotypically altruistic but overall still selfish
-probability that relatives share a particular gene = coefficient of relatedness (r)
diploid = egg + sperm = child

Question 5

Kin selection continued:
probability of any one gene being shared by: 
parent and offspring (r) 
identical twins
sibligs
grandparents
great grandparents

Answer 5

0. 5
1. 0
2. 5
3. 25
4. 125

Question 6

2 types of fitness in kin selection?
Costs 
benefits
name of rule for B>C
equation?

Answer 6

relatives contribute to an individuals fitness
(fitness = measure of genes contributed to next generation)
2 components:
1)direct fitness = own personal reproduction
2) indirect fitness = reproduction of kin
total fitness = inclusive fitness
-need to look at costs and benefits to explain altruism
Benefits> Costs = Hamiltons rule

Benefit = impact of altruistic act on indirect fitness eg. kins reproduction
=no.of kins offspring x r
Cost = impact of altruistic act on direct fitness eg. personal reproduction
=no. of offspring foregone x r (always 0.5 as they’re own offspring)

so,
(Nk x r) > (Ns x 0.5)
B C

Question 7

Genes for self sacrifice? (kin selection)

Answer 7

causes you to sacrifice self before reproduction, on assumption most people will produce 2 children
- gene will increase in freq if act saves life of kin (sacrifice self to save relatives who will go on to reproduce)
example of badgers - Hoogland (1983)
badgers alarm calls - more likely to give alarm call if relatives are nearby (want to help own kin = influence on indirect behaviour)

Close genetic relatives= more likely to help

Question 8

Mutualism
(another hypothesis for altruism)
male birds territory

Answer 8

animals don’t have to be related here as it benefits both
-co-operation may occur because each p gains a net survival/ reproductive benefit
Territorial behaviour in male birds
- they will sometimes allow other birds in territory if it reduces defence time (B) even though it may reduce amount of available food (C)
- will only allow it if B>C

Question 9

Manipulation
(another hypothesis for altruism)
cuckoos

Answer 9

donors may be tricked into behaving altruistically

eg cuckoo bird - brood parasites - lay eggs in other nests so another bird has to raise young

Question 10

Reciprocal altruism
(another hypothesis for altruism)
vampire bats

Answer 10

you do something nice for me, i’ll do something nice for you( eg, grooming behaviour in chimps)
doesn’t require ps to be related
– problem of cheating eg. benefit then don’t return behaviour because of temporal delay
to avoid: may give rise to very inter-individual recognition
Wilkinson (1984) - regurgitation of blood by vampire bats - some bats would beg for blood from other roosts but, regurgitation only occured between frequent roostmates or relatives