Sexual Selection

Question 1

Definition of Sexual Dimorphism

Answer 1

phenomenon in which individuals of different sexes of the same species have different genotypes and/or phenotypes

differences in gametes, reproductive organs,

Question 2

anisogamy

Answer 2

differences in gametes between sexes
unequal sized gametes

Question 3

Chromosomes in males and females
Genetic Males and Females

humans and birds

Answer 3

Males: XY and ZZ
Females: XX ZW

Question 4

Gametic Males

Answer 4

sperm producers

Question 5

Gametic Females

Answer 5

egg producers

Question 6

gametic definitions of sex only applies to species with

Answer 6

anisogsmy (unequal sized gametes)

Question 7

Types of Sexual Dimorphism

Answer 7

size, armaments (anatomical weapons), ornamenets

Question 8

Sexual Selection

Answer 8

-sexually selected traits function to enhance mating success
- subset of natural selection but can be useful to consider seperately

Darwin: depends on advantage which certain indivduals have over other indivduals of the same sex and species exclusive to reproduction

Question 9

Factors that contribute to fitness

Answer 9

Natural Selection: reproductive rate, survival
Sexual Selection: Number and Quality of Mates

Question 10

Two Types of Sexual Selection

Answer 10

Intra and Inter sexual selection

Question 11

Intrasexual selection

Answer 11

competition
differences between indivudals of the same sex
often but not always male-male

access to other sex

Question 12

Intersexual Selection

Answer 12

choosiness
interaction between males and females

Question 13

what determines strength sexual selection

Answer 13

number and quality of mates = variance in mating success

Question 14

Operational Sex Ratio

Answer 14

anything that alters the receptivity of one sex to mating or their potential for mating

Sex Ratio vs operational sex ratio

3 males and 3 females (2 of three females are not availiable/receptive to mating): equal sex ratio. operational sex ratio is male bias

Question 15

what drives potential reproductive rates

Answer 15

gamete expenditure

egg resource rich, few and large while sperm in inexpisve and many and small

Question 16

Parental Investment Theory

Answer 16

• Sexes of some species differ in their reporductive investment
• each offspring is produced from sperm and egg
• members of sex that invest little will compete among themselves to mate with members of the sex that invest more

Question 17

if the only investment in offpsring is gametes

Answer 17

competition between males and choosiness in females

Question 18

two forms of intrasexual selection competition

Answer 18

pre-copulatory: # of copulations
post- copulatory: success of copulations

Question 19

pre-copulatory examples

manifestation of competition

Answer 19

fighting behaviour, social status, territoriality

Question 20

Post- copulatory

manifestation of competition

Answer 20

mate guarding, copulation duration (more sperm and egg produced), sperm removal, sperm plugs, anti-aphrodisiacs

Question 21

Alternative reproductive strategies

Answer 21

variation in pehnotypes and behaviour within a sex

Question 22

Negative Frequency Dependant

Answer 22

fitness of a stretegy highest when that strategy is rare in the population

Question 23

Mate choice

mating bias, mating preference, and mate choice is the same thing

Answer 23

any trait of one sex that biases the mating success of other sex towards preferred type

trait= behaviour, morphology

Question 24

mechanisms individuals choosing

Answer 24

visual cues, tacile cues, acoustical cues, olfactory cues

females prefer complex calls

Question 25

* traits are common and preferred by mates and there is a selection for *

Answer 25

1. elaborate 2. eloboration

Question 26

Hypothesis for Choice

Answer 26

indirect and direct benefits

Question 27

direct benefits

Answer 27

- involve direct natural selection on the individual making the choice. - chooser produces more offspring ## Footnote female choosiness based on resources rather than male attributes male trait is indicator of these resources

Question 28

indirect benefits

Answer 28

- involve genetic benefits to offpsring of the individual making the choice - choosers offspring are of higher genetic quality and more fit ## Footnote females prefer males traits that indicate high genetic quality. large peacock display size preferred

Question 29

males traits that are indicators of resource provisioning or other direct benefits

Answer 29

- territory quality - defense - parental care - lack of parasites (STIs)

Question 30

indirect benefits

Question 31

parental investment theory

Answer 31

- sexes differ in their reproductive investment - members of the sex that invest little in offspring will compete among themselves to mate with members of the sex that invest more in offspring ## Footnote when males invest a lot relative to females= males choosiness and female competition

Question 32

environmental effects on relative PI and mate choice

Answer 32

- resource levels decline = male avaliability declines, venefit to female of resources from males increases Predictions: male choice and female competition

Question 33

How do alternative reproductive strategies influence female choice

Answer 33

parental males offer direct benefit to females ## Footnote ex: defend nests and provide care to young