Ch. 10: Social Behavior

Question 1

social behavior

Answer 1

interactions w/ members of one’s own species, including mates, offspring, other relatives, and unrelated individuals

Question 2

benefits of living in groups

Answer 2

survival (dilution effect), feeding (clustered around resources, hunting in packs), mating (availability of mates), 1 can warn others of danger

Question 3

costs of living in groups

Answer 3

predation (large groups are easy to be spotted by predators), competition, disease (spread quickly is close groups)

Question 4

lek

Answer 4

location of an animal aggregation to put on a display to attract the opposite sex

Question 5

dilution effect

Answer 5

reduced, or diluted, probability of predation to a 1 animal when its in a group

Question 6

territory

Answer 6

any area defended by 1+ individuals against the intrusion of others
- defending high quality territory ensures good resources

Question 7

dominance hierarchy

Answer 7

social ranking among individuals in a group, typically determined through fighting or other contests of strength of skill

Question 8

linear dominance hierarchy

Answer 8

1st ranked member dominates all other members, 2nd ranked dominates all but 1st ranked, and so on…

Question 9

donor

Answer 9

individual who directs a behavior toward another individual as part of a social interaction

Question 10

recipient

Answer 10

individual who receives the behavior of a donor in a social interaction

Question 11

4 types of social behavior:

Answer 11

cooperation, selfishness, spitefulness, altruism

Question 12

cooperation

Answer 12

donor and recipient both experience increased fitness from interaction (+/+)

Question 13

selfishness

Answer 13

donor experiences increased fitness and recipient experiences decreased fitness (+ donor/ - recipient)

Question 14

spitefulness

Answer 14

interaction reduces the fitness of both donor and recipient (-/-)

Question 15

altruism

Answer 15

increases fitness of recipient and decreases fitness of donor (- donor, + recipient)

Question 16

direct fitness

Answer 16

fitness an individual gains by passing on copies of its genes to its offspring

Question 17

indirect fitness

Answer 17

fitness an individual gains by helping relatives pass on copies of their genes

Question 18

direct selection

Answer 18

selection favors direct fitness

Question 19

indirect selection (kin selection)

Answer 19

selection favors indirect fitness

Question 20

coefficient of relatedness

Answer 20

numerical probability of an individual and its relatives carrying copies of the same genes from a recent common ancestor
- B x r > C

Question 21

B x r > C variables:

Answer 21

• B = benefit to the recipient
• r = recipients coefficient of relatedness to the donor
• C = direct fitness cost to the donor

Question 22

for altruism to evolve, cost-benefit ratio must be…

Answer 22

< coefficient of relatedness b/w donor and recipient

Question 23

eusocial (“truly” social) species 4 characteristics:

Answer 23

1. several adults living together in group
2. overlapping generations of parents and offspring living together in same group
3. cooperation in nest building and brood care
4. reproductive dominance by 1 or few individuals, and presence of sterile individuals

Question 24

caste

Answer 24

individuals w/in social group sharing specialized behavior

Question 25

haplodiploid

Answer 25

sex-determination system in which 1 sex is haploid and other is diploid

Question 26

queen

Answer 26

dominant egg-laying female in eusocial insect societies

Question 27

dilution effect

Answer 27

reduced/diluted probability of predation to a single animal when its in a group
- strength in numbers
- more individuals watching, increases individuals time for feeding (less time individually watching)

Question 28

social behaviors ___, ____, and ___ , and thus are subject to ___.

Answer 28

• have a genetic basis, instinctual basis (innate), and learned behaviors
• subject to natural selection

Question 29

selection has favored ___ and ____

Answer 29

cohesive groups and constrained antagonism (hierarchical order from competition)

Question 30

trade-offs in group food gathering

Answer 30

larger groups are better at locating food, but food must be shared among all members

Question 31

territories can be… (2):

Answer 31

1. transient territory
2. relatively permanent territory

Question 32

home range is

Answer 32

a much larger area than a territory; area is used but NOT entirely defended
- may defended center of home range
- range of 1 group (1 species in 1 area)

Question 33

egalitarian ranking

Answer 33

linear ranking system (highest (alpha) –> lowest)
- ex: chickens
- once hierarchy established; ranked dominant and submissive

Question 34

despotic social order

Answer 34

1 alpha, everyone else equally less than alpha

Question 35

benefits of being a dominant individual

Answer 35

reproductive success, foraging success

Question 36

costs of being a dominant individual

Answer 36

higher metabolic rates, higher levels of stress hormones, danger of being killed

Question 37

benefits of being a subordinate individual

Answer 37

lower risk of injury from fighting, avoid stress, protection by dominant leader

Question 38

costs of being a subordinate individual

Answer 38

subject to leader, reduced access to food, reduced access to shelter/reproduction

Question 39

% normal relations b/w family members

Answer 39

50%

Question 40

what situation would create 75% relatedness b/w family members?

Answer 40

only if there are “sister-wives”
- husband marries wife, wife dies, husband re-marries her sister, their child has 75% relatedness to siblings

Question 41

inclusive fitness

Answer 41

direct and indirect fitness

Question 42

2 known animals that are eusocial (other than insects):

Answer 42

• nakedmole rats
• damaraland mole rat

Question 43

Primary helpers

Answer 43

sons of parents that feed and protect chicks

Question 44

Secondary helpers

Answer 44

unrelated males that help to feed and protect chicks

Question 45

Delayers

Answer 45

unrelated and do not help and wait until the second year to reproduce
- after 2 years, delayers have reduced inclusive fitness relative to secondary helpers

Question 46

naked mole rats…

Answer 46

• only mammal w/o pain receptors on skin
• no cancer

Question 47

inclusive fitness =

Answer 47

(indirect fitness)*(direct fitness)