Lecture 17: Social Behaviors (Cont.)

Question 1

What are the four categories of social behavior (non-reproductive)?
How does it affect the donor versus the recipient, respectively?

Answer 1

Cooperation/mutualism (++), selfishness (+-), altruism (-+), spitefulness (–).

Question 2

What is direct fitness favored by?

Answer 2

Direct selection (offspring produced by yourself)

Question 3

What is indirect fitness favored by?

Answer 3

Indirect or kin selection (helping relatives produce offspring).

Question 4

What category of social behavior often is used to increase indirect fitness?

Answer 4

Altruism.

An act that benefits the receiver at a cost to the actor. Leads to increased indirect fitness, not direct fitness.

Question 5

When should altruism arise?
(Hamilton’s Rule).

Answer 5

rB - C > 0 OR rB > C

r: genetic relatedness between recipient to actor
B: reproductive fitness benefit gained by recipient of cooperative act
c: reproductive cost of individual performing the cooperative act.

Question 6

True or false: Inclusive fitness only includes offspring due to the behavior of the actor.

Answer 6

True.

Question 7

How do you calculate the relatedness coefficient based on a diagram?

Answer 7

Count the number of “lengths”/paths and multiply that number by 0.5 raised to the power of L which is the number of generation links.

Ex. r = 2(0.5)^2 = 0.5

Question 8

How do you calculate the indirect fitness benefit to an actor?

Answer 8

Relatedness coefficient x Benefit to the recipient.

Question 9

How would you solve for the minimum r based on B and C?

Answer 9

r > C/B

Question 10

What does r, B, and C stand for in Hamilton’s rule?

Answer 10

r: relatedness coefficient
B: benefit to dominant (mean offspring produced by dominant - mean offspring produced by solitary)
C: cost to submissive (mean offspring of solitary - mean offspring of subordinate)