L19 - Cooperative behaviour and kin selection

Question 1

What is cooperative behaviour?

Answer 1

A behaviour in which one organism pays a cost and another receives a benefit (in terms of fitness)

Question 2

Why is cooperative behaviour a problem?

Answer 2

Natural selection favours genes that increase individual fitness so selfish behaviours should dominate

Question 3

What are the 2 solutions to cooperative behaviour?

Answer 3

Direct benefits - reproductive success of the cooperator is increased

Indirect benefits - reproductive success of individual sharing the cooperators genes is increased

Question 4

What is direct reciprocity?

Answer 4

When individuals continue to help each other, increases the fitness of the cooperating individual and the recipient of the behaviour (but requires repeated interactions) - mutually beneficial relationship

Question 5

What is an example of direct reciprocity?

Answer 5

Between cleaner wrasse and larger fish - wrasse gets a meal and larger fish gets parasites removed

Question 6

What is altruistic behaviour?

Answer 6

Behaviours that benefit the recipient but not the cooperator

Question 7

Give an example of an altruistic behaviour

Answer 7

Vampire bats blood sharing:
- will regurgitate blood to individual not successful in finding food
- blood sharing is typically between ‘buddy’ pairs (= repeated interactions) or relatives
- individuals cooperate on the first interaction and in subsequent interactions copy the behaviour of the other individual

Question 8

What is indirect reciprocity?

Answer 8

Apparent altruistic behaviours where the benefits come later

Question 9

What are reputational benefits?

Answer 9

When an altruistic behaviour pays off in the long term because the reputation of the cooperator has gone up

Question 10

What is kin selection?

Answer 10

A process by which traits are favoured because of their beneficial effects on the fitness of relatives

Question 11

What are the indirect fitness benefits of kin selection?

Answer 11

Helping your relatives allows cooperators to spread their genes without having to necessarily reproduce themselves

Question 12

What is Hamiltons rule?

Answer 12

Cooperative genes should increase in frequency when the benefits (B) of cooperating are greater than the costs (C), depending on the level of relatedness (r):
So rB - C > 0

Question 13

In salamanders, what is an example of a different treatment of kin?

Answer 13

Salamanders perform cannibalism but:
- cannibalism occurred later in kin associations
- therefore, some form of kin recognition exists

Question 14

In guppies, what is an example of a different treatment of kin?

Answer 14

Full sibs spent more time shoaling together and swam closer together than half sibs

Question 15

How do animals recognise kin?

Answer 15

• environmental cues: familiarity or shared environment
• phenotype and self-referent matching
• “green-beard” effects

Question 16

What is the “green beard” effect?

Answer 16

Individuals preferentially direct cooperative behaviours to others sharing a distinctive genetic marker…e.g. a ‘green beard’

Question 17

Give an example of cooperation leading to increases in inclusive fitness

Answer 17

Male turkeys court as solitary males or in coalitions consisting of a dominant and subordinate male, only the dominant male mates with the females.
- Coalitions only happens with related male turkeys
- According to Hamilton’s rule there is a net benefit

Question 18

When can cooperation evolve?

Answer 18

When it offers:
» DIRECT FITNESS BENEFITS
- increases the number of offspring produced by cooperator
- total number of offspring an individual can produce on their own

> > INDIRECT FITNESS BENEFITS
-increases in the fitness of the cooperators relatives
-“excess” offspring due to assistance to relatives