Kin Selection And Social Behavior

Question 0

Direct fitness

Answer 0

From own reproduction

Question 1

Inclusive fitness

Answer 1

Contribution of genes to next generation through direct and indirect fitness

Question 2

Indirect fitness

Answer 2

From additional reproduction by relations

Question 3

Kin selection

Answer 3

Selection favoring alleles that increase indirect fitness

Question 4

Hamilton’s rule

Answer 4

An altruistic allele can spread by kin selection if rb-c>0 or rb>c where r is the relatedness of the individual, b is the fitness benefit to the recipient (extra # of offspring recipient produces), and c is the fitness cost to actor (# offspring actor gives up)(basically if benefits outweigh the costs) r=0.5 for immediate family

Question 5

Coefficient of relatedness, r

Answer 5

Probability that two individuals share and allele that is identical by descent

Question 6

Effect of r, b, and c on Hamilton’s rule

Answer 6

Higher r means more likely to evolve altruistic behavior, lower b also mean more likely to behave altruistically, lower c means more altruism

Question 7

Relatedness of immediate family in normal diploid species

Answer 7

r=0.5

Question 8

Ground squirrel and prairie dog alarm call

Answer 8

Warn others of threat, females stay close so higher relatedness in area, protect others and increase overall fitness (indirect)

Question 9

Eusociality

Answer 9

Extreme form of altruism, three characteristics:

1. Overlap of generations
2. Cooperative brood care
3. Specialized castes of non-reproductive (sterile) individuals

Question 10

Level of relatedness in eusocial species

Answer 10

Hypothesis: eusociality tends to evolve in species with higher relatedness because high r favors altruism

Question 11

Haplodiploidy

Answer 11

Males develop from unfertilized eggs (n), females develop from fertilized eggs (2n)

Question 12

Hamilton’s prediction as to why Hymenoptera more likely to evolve eusocial behavior

Answer 12

High relatedness due to haploid sex determination/haplodiploidy, females related more closely to sisters than own children (r=0.75) vs to own child (r=0.5)

Question 13

Hymenoptera and eusociality

Answer 13

Most Hymenoptera not eusocial, higher r not always lead to eusociality

Question 14

High r and eusociality

Answer 14

Not always associated, most haploid, inbred, and asexual species have high r but are not eusocial

Question 15

Factors affecting eusociality

Answer 15

1. Nesting behavior, extended parental care
2. Limited breeding opportunities, costly dispersal
3. Group defense against predators

Question 16

Human sociobiology

Answer 16

Study of evolutionary basis of human behavior
Criticisms:
1. Are human behaviors really adaptive?
2. Does sociobiology condone criminal, sexist, racist behavior?
3. Does it imply that we can’t change our behavior?