8 - Kin selection

Question 1

In altruism, can you completely give up all of your fitness?

Answer 1

No, giving up all reproductive success would not evolve by natural selection. Though, you can give up individual reproductive success in lieu of kin genes being passed on.

Kin selection

Question 2

True or false? Altruism ends up with a net benefit to the altruist

Answer 2

Usually true. For this system to work, an altruist must be surrounded by other altruists.

Question 3

If a population has altruists and non altruists, how can it work based on the proportion of interactions?

Answer 3

Altruists must interact with other altruists more than non-altruists interact with altruists (eg. if care is more likely to be directed to individuals with altuism)

Having altruism must be preductuve of the recipient having altruism too

Question 4

What is Hamilton’s rule?

Answer 4

According to Hamilton’s rule, kin selection causes genes to increase in frequency when the genetic relatedness of a recipient to an actor multiplied by the benefit to the recipient is greater than the reproductive cost to the actor.

Question 5

What is a formula that is good for expressing Hamilton’s rule?

Answer 5

rb > c

(relatedness)(benefit) is greater than (cost)

r = coefficient of relatedness

Question 6

What is the coefficient of relatedness (r) for:

• parents/offspring
• siblings

Answer 6

• Parents give half their genes to each their offspring (r = .5)
• Full siblings (r = (.5x.5) + (.5x.5) = .5)
• Half siblings (r = (.5x.5) = .25)
• First cousins are related through grandparents (.5^4 + .5^4 = .125)

You can figure any of these out from r = Σ(0.5)^L

• Where L = the number of parent-offspring (generational) links

Question 7

Kin selection is not just about altruism, what is it?

Answer 7

Selection for traits that increase the survival of close relatives including offspring and non-descendant kin.

Question 8

What is direct fitness?

Answer 8

Fitness gained by increased survival of offspring because of the individual’s actions.

Question 9

What is indirect fitness?

Answer 9

Fitness gained by increasing survival of non-descendant kin because of your actions.

Question 10

What are the two fitness components of kin selection?

Answer 10

• Direct fitness
• Indirect fitness

(inclusive fitness = some of it from your own offspring, some from other’s offspring)

Question 11

Is calling when predators near more likely when there are:

• no close relatives
• Only non descendant close relatives
• Only offspring

Answer 11

• No close relatives (least likely to call)
• Only non descendant close relatives
• Only offspring (most likely to call)

Question 12

How do animals know that there’s kin around (differential behaviour towards kin/non kin driven by kin recognition)?

Answer 12

• Social learning (growing up with certain individuals), siblings/non-siblings raised together less likely to get in fight than those raised apart).
• Phenotype matching (eg. olfactory, rearing together barely helps toleration to non-kin)

Question 13

Having altruism must be predictive of the recipient having altruism too.

How is this possible? (3)

Answer 13

• If altruists interact repeatedly (reciprocity)
• If altruism occur in groups (group selection)
• If altruists are related (kin selection)

Question 14

Describe how you can calculate the coefficient of relatibility (r) for first cousins.

Answer 14

Cousins = L=4 (1 for parent, 1 for grandparent, 1 for aunt, 1 for cousin)

Cousin 1 = (.5)^4 = .0625
Cousin 2 = (.5)^4 = .0625

0.0625 + 0.0625 = .125

r = .125

Question 15

What is inclusive fitness?

Answer 15

The direct fitness gained by increased survival of offspring, due to individual’s actions AND the indirect fitness gained by increased survival of non-descendent kin because of the individuals actions

An essential component in explaining kin selection