Evolution of sociality

Question 1

What are the four types of interaction?

Answer 1

Cooperation, Selfish, Altruism and Spite.

Question 2

Explain each type of interaction.

Answer 2

Cooperation is when both players benefit, Selfish is when only one player benefits, altruism is when one player gives up their gain to benefit the other and spite is when no member gains.

Question 3

What is the difference between cooperation and altruism?

Answer 3

Cooperation is when both individuals behave in a way that benefits the other, whereas altruism is when the focal individual behaves in a way that benefits their social partner at a cost to themselves.

Question 4

What is cooperation vulnerable to?

Answer 4

Cheating - selfishness.

Question 5

Why is altruism confusing to evolutionary biologists?

Answer 5

The actor loses fitness at the benefit of the recipient.

Question 6

What can influence the act of positive social interactions such as altruism?

Answer 6

Relatedness between individuals.

Question 7

What does it mean to be related?

Answer 7

Relatives share some fraction of their alleles. THe likelihood of having the same allele at a locus is predictable and a function of relatedness.

Question 8

What is direct fitness of an allele?

Answer 8

The influence of an act on the fitness of an an individual carrying the allele, such as behaviour that affects the number of surviving offspring an individual produces.

Question 9

What is indirect fitness of an allele?

Answer 9

The influence of an act by one individual carrying an allele on the fitness of other individuals carrying shared alleles, such as behaviour that affects the number of surviving offspring a relative produces.

Question 10

What is inclusive fitness?

Answer 10

The sum of direct fitness and indirect fitness.

Question 11

When is altruism favoured?

Answer 11

Whenever the benefit to the relatives for being altruistic outweighs the cost to the individual.

Question 12

What is the equation associated with inclusive fitness?

Answer 12

rB - C where r is the relatedness, B is the benefit to the relatives and C is the cost to the individual

Question 13

What is an example of altruism in nature?

Answer 13

Squirrels adopting a squirrel from another little. This increases the survival of the juvenile but reduces the survival of the mother’s natal litter due to adding a juvenile.

Question 14

What are the benefits and risks of acting altruisitically to non-relatives?

Answer 14

There may be reciprocal altruism, but there is also a risk of cheating.

Question 15

What is game theory?

Answer 15

A way to look at interactions between individuals in which players take different strategies to solve a scenario that involves an interaction.

Question 16

What is the optimal strategy in a game?

Answer 16

The evolutionary stable strategy (ESS).

Question 17

What is the prisoner’s dilemma?

Answer 17

A situation in which two criminal suspects are caught by police and taken to two separate rooms to be interrogated. They can either both admit guilty and take 1 year each or testify and be freed, leaving their partner with 5 years. If both testify, both get 3 years.

Question 18

What are the 4 payoffs in the prisoner’s dilemma?

Answer 18

Reward (mutual cooperation), Punishment (mutual defection), Temptation (to defect) and Sucker’s payoff (cooperating when partner defects).

Question 19

In the prisoner’s dilemma, if evolution maximised the average fitness of individuals which strategy should evolve?

Answer 19

The Reward payoff - both members cooperate.

Question 20

In the prisoner’s dilemma, when is the fitness of an individual highest?

Answer 20

The temptation payoff - defecting when the partner cooperates.

Question 21

What strategy does evolution favour?

Answer 21

A strategy that always defects - worst outcome in terms of average fitness.

Question 22

Why does natural selection choose strategies that do not lead to highest average fitness/

Answer 22

As the success of a strategy relies on the strategies played by others. The ESS is a strategy such that if all members of a population were to adopt it, no mutant strategy could invade.

Question 23

Is defecting always the ESS?

Answer 23

If the individuals only interact once, cheating is always favoured but this can make it unlikely to cooperate with the partner in the future.

Question 24

What is tit-for-tat?

Answer 24

Deciding how to act based on the way a partner acted in a previous encounter.

Question 25

What is an example of altruism that is based on interactions between partners rather than relatedness?

Answer 25

Food sharing in vampire bats.

Question 26

What will increase a players chance of choosing the selfish strategy?

Answer 26

A lower cost of fighting or higher value of resource.

Question 27

What is sexual conflict?

Answer 27

Conflicts between the interests of males and females when mating.

Question 28

What is parent’s view of parent-offspring conflict?

Answer 28

Parents are equally related to all of their offspring and value all offspring equally. They balance their investment in each offspring against the cost to producing more offspring. Selection optimizes the total number of offspring they can produce.

Question 29

What is an offspring’s view of parent-offspring conflict?

Answer 29

That offspring are more related to themselves than to their parent’s future offspring, and they value themselves more highly than they value their siblings. It is in their interest to extract more parental care from their parents at the cost of their siblings.

Question 30

What are intra-genomic conflicts?

Answer 30

Conflicts that arise between alleles within the same genome.