Unit 3

Question 1

Define sexual selection.

Answer 1

Selection for traits that increase mating success

Question 2

Describe intersexual vs intrasexual selection

Answer 2

Inter: look sexy for opposite sex (colours, displays, etc)
Intra: compete against same sex (antlers, manes, large body)

Question 3

What are two types of potential gains females get from selecting a specific phenotype of male?

Answer 3

1) Direct benefits are non-genetic benefits (feeding, parental care, provide resources)
2) Indirect benefits are genetic benefits (gain good genes, Fisher’s runaway)

Question 4

What is Fisher’s runaway selection? What is chase-away selection?

Answer 4

Runaway selection is the positive feedback loop of female preference and male phenotype. Chase-away is an arms-race between a female defence trait and male offence trait.

Question 5

What are four scenarios where biased sex allocation may occur?

Answer 5

1) Local mate competition; have only one male bc that’s all you need (mostly inbreeding bugs)
2) Local resource competition; if males disperse and female stay, only have one female and a bunch of males
3) Local resource enhancement; have lots of daughters if they help you raise kids
4) Conditional sex allocation; if resources are limited, it may be hard to produce big males, but you could produce a few small females

Question 6

What are three factors that could lead to conditional sex allocation?

Answer 6

1) Quality of environment
2) Quality of mother
3) Quality of mate

Question 7

What are the two main types of polygyny?

Answer 7

1) Female-defence
2) Resource-defence

Question 8

What conditions lead to monogamy in mammals?

Answer 8

Solitary females who require defence. Males will defend the range. Especially when resources are limited

Question 9

What do male mammals tend to do if females are solitary but do not need defence?

Answer 9

Males live solitary and look for females in oestrus.

Question 10

What do male mammals tend to do if females are social and stay in one place?

Answer 10

Males do range defence, there may be multiple males on the same range

Question 11

What do male mammals tend to do if females are social but move around?

Answer 11

If it’s predictable movements then males will defend a specific range that females need to go to. If it’s predictable when the females go into oestrus then males will only protect during that season. If females are unpredictable then males may permanently guard the females.

Question 12

What is a lek?

Answer 12

An area where males group together to do their sexual displays

Question 13

What are three reasons that some birds are monogamous?

Answer 13

1) Obligate monogamy: only way to raise chicks is two parents
2) Males can’t provide enough for multiple females
3) Female aggression towards other females

Question 14

How does sexual conflict effect parental care?

Answer 14

Females may have a different strategy than males and this leads to manipulation

Question 15

What is the relatedness coefficient for an individual and their parents, siblings, half-siblings, cousins?

Answer 15

1/2 for parents and siblings, 1/4 for half siblings,
1/8 for cousins

Question 16

What is Hamilton’s value of kin selection?

Answer 16

rb-c

r: relatedness coefficient
b: benefit
c: cost

Question 17

What is inclusive fitness in kin selection?

Answer 17

Direct fitness of self and descendants and indirect fitness from other kin combined

Question 18

What is the difference between snow drift and Prisoner’s dilemma?

Answer 18

Snow drift it depends on relative b vs c, and you get the same benefit if you both co-op. In prisoner’s the b and c are absolute, and you share the benefit if you both co-op.

Question 19

What are three conditions that may lead to reciprocity?

Answer 19

1) Many opportunities to interact and pay back.
2) Benefit of receiving is high, cost of donating is low
3) Relationship to other individual.

Question 20

What are two reasons for why individuals don’t breed on their own, but instead try to help kin?

Answer 20

1) Lack of opportunity (no vacant habitats)
2) Lack of mates

Question 21

Why would individuals want to help kin, instead of just doing nothing?

Answer 21

1) Indirect fitness; relatedness
2) Direct fitness; mutualism, delayed benefits, avoiding punishment for not helping (enforcement)

Question 22

What is Darwinian anthropology or human behavioural ecology?

Answer 22

See humans as any other species

Question 23

What is gene-culture coevolution / dual inheritance theory?

Answer 23

Genes and culture evolve together