Lecture 12: Individual selection and altruism

Question 1

Altruistic behaviour:

Answer 1

is behaviour that benefits other individuals at a cost to the altruistic individual

Question 2

e.g. of altruistic behaviour

Answer 2

THE HONEY BEE
-dont mate but provide for queen bee who does, jepodising their own fitness.
GUARD BEES
-sting someone/something but then dies hours later as loses sting
VAMPIRE BAT
-regurgitates its food for neighbouring individuals

Question 3

How could altruistic behaviour evolve?

Answer 3

1) the behaviour is not really altruistic
2) Altruism is reciprocated at a later time (vampire bats)
3) adaptions have evolved for ‘the good of the species’
- alarm calls
- ritualised fighting
- senescence
BUT.. such adaptations could not have evolved by individual selection
4) adaptions have evolved for the good of the gene
-Altruisitc behaviour occurs at the level of the individual. Behaviour is selfish at the level of the gene

Question 4

what does the rate of individual selection is effective depends on…

Answer 4

depends on the length of a generation.

Question 5

the rate at which group selection is effective depends on ..

Answer 5

the rate at which a whole group replaces itself

Question 6

adaptions have evolved for the good of the gene explanation:

Answer 6

Gene x (phenotype increases survival/reproduction of individual) —> Gene x (Gene and individual are selfish)

Gene x –altruism–> Gene y –> Geney y =GENE NOT PASSED ON

Gene x –altruism–> Gene x –> Gene x = gene passed on beneficial

Question 7

Kin selection:

parent - child

Answer 7

% of genes shared =

50%

Question 8

Kin selection:

grandparent-child

Answer 8

% of genes shared =

25%

Question 9

Kin selection:

full siblings

Answer 9

% of genes shared =

50%

Question 10

Kin selection:

half siblings

Answer 10

% of genes shared =

25%

Question 11

% of genes shared =

Answer 11

coefficient of relatedness = r

Question 12

Evolution of altruistic behaviour:

Answer 12

1) cost of altruism (c)
2) benefit to recipient (b)
3) coefficient of relatedness (r)

Question 13

with an altruistic act;

Answer 13

• If C is high then genes passed to own offspring is low.

- if r X b is high then genes passed through kins offspring is high

Question 14

Altruism will evolve when

Answer 14

rb>c

Question 15

whats hamilton rule:

Answer 15

rb>c

Question 16

e.g. for testing altruism; Helpers at the nest - Seychelles warbler

Answer 16

c = number of chicks helper would have if it bred 
b = extra chicks the pair raises 
r = relatedness of helper to pair 
c&b from breeding records 
r from DNA fingerprinting