Sexual Selection - 20

Question 1

Define sexual dimorphism

Answer 1

differences between males and females

Question 2

Define ecological selection

Answer 2

differential reproduction success due to individual variation in survival and reproductive output

Question 3

Define sexual selection

Answer 3

differential reproductive success due to individual variation in mating success

Question 4

Define intrasexual selection

Answer 4

contests between members of the same sex (ex. male-male competition)

Question 5

Define intersexual selection

Answer 5

selection via mate choice (ex. non-random mate choice by females)

Question 6

What are 4 asymmetries in sexual reproduction

Answer 6

1. parental investment
2. limits on reproductive success
3. mating systems
4. operational sex ratio

Question 7

Define anisogamy

Answer 7

male and female gametes are different sizes

Question 8

Bateman’s principle (2)

Answer 8

male reproductive success is limited by access to females and produce many cheap gametes
whereas female reproductive success is limited by access to resources and produce few gametes

Question 9

what mating systems have the highest and lowest strength of selection

Answer 9

monogamy is lowest
polygyny and polyandry are highest

Question 10

Is sexual selection more important for males or females and why

Answer 10

males because intrasexual selection includes direct competition, sperm competition, and infanticide
compared to intersexual competition of female choice

Question 11

Explain sperm competition

Answer 11

either having larger sperm, higher number, copulatory plug, pheromones, special structures (remove any sperm that were already present and then fertilize)

Question 12

What is infanticide

Answer 12

males often killed unweaned offspring to allow the female to be ready to reproduce again, not to show dominance

Question 13

What are the direct benefits that come from female choice

Answer 13

females benefit from increased nutrition, provisioning, parental care that increases reproductive output or the quality of their offspring

Question 14

What are the indirect benefits of female choice

Answer 14

1. good genes hypothesis
2. sexy sons hypothesis

Question 15

What is the good genes hypothesis

Answer 15

genetically superior mates produce offspring with higher fitness

Question 16

What is the sexy sons hypothesis

Answer 16

females mating with preferred fathers produce sons with higher mating success and females with that preference

Question 17

What are nuptial gifts an example of

Answer 17

direct benefit - male present partner with food, and the bigger the food the longer the duration of copulation and number of sperm transferred

Question 18

What are examples of direct benefits for females

Answer 18

1. nuptial gifts
2. female consuming portion of spermatophore
3. sexual cannibalism
4. adaptive male suicide

Question 19

What is the likely cause of sexual dimorphism arising

Answer 19

female choice is responsible

Question 20

Stronger sexual selection on females leads to the expression of….

Answer 20

secondary sexual characters in females and not males

Question 21

What is Bateman’s gradient and sex-role reversal

Answer 21

in species where males have more potential investment then females, then females are limited by males for reproductive success

Question 22

Explain how sexual selection differs in plants

Answer 22

sexual selection doesn’t increase due to increased mating, but due to increases in accessibility to pollen

Question 23

What kind of wind-pollinated species are the most successful

Answer 23

1. male flowers have larger reproductive parts and the larger perianth
2. female flower has larger reproductive parts and the larger perianth
   (based on perianth)