Sexual Selection

Question 1

Differential Reproduction

Answer 1

Critical to natural selection

Question 2

Sexual Selection

Answer 2

selection arising from differences in mating success

Selection arising from competition between or within sexes in a single population

Question 3

Adaptations

Answer 3

Features which enhance relative fitness and thus lead to greater reproductive success

Question 4

Materials For Selection

Answer 4

Differences in phenotype that have consequences for survival and reproductive success

Question 5

Copulation (reproductive model)

Answer 5

Individuals recognize and encounter conspecifics of the appropriate sex

Means of transmitting gametes

requires time and energy searching for mates

number of potential encounters may be limited so each copulation potentially limits future choices or opportunities

Question 6

Spawning (reproductive model)

Answer 6

Coordination of members of population with respect to timing of spawning

typically prevents extensive parental care

concentration and density of gametes appropriate to environment

gamete recognition mechanisms

Question 7

Polyandry

Answer 7

oldest and largest individual is a female, males compete for access

• better guarantee of successful reproduction
• promote competition among males and among their sperm –> more variation possible
• multiple males can procure more resources for the female

Question 8

Polygyny

Answer 8

Oldest and largest individual is a male, maintains group of females

males maximize mating opportunities

Question 9

intrasexual

Answer 9

sexual selection between members of one sex for access or opportunity

Question 10

intersexual

Answer 10

preference by one sec for certain phenotypes in mates

Question 11

what is assortative mating? what two types are there?

Answer 11

contrast to random mating

positive assortative mating and negative assortative mating

Question 12

Positive assortative mating

Answer 12

preference for similar phenotype (possible inbreeding)

Question 13

Negative assortative breeding

Answer 13

preference for different phenotype

may make it hard to maintain species boundaries

Question 14

what are the components of reproductive fitness?

Answer 14

Viability
Mating Success
Fecundity
segregation advantage
gamete viability
fertilization success

Question 15

Who typically picks for mating

Answer 15

Females

Question 16

Sneaking

Answer 16

pretending to be females

Question 17

Cheating

Answer 17

Having multiple mates

Question 18

Zahavi Handicap hypothesis

Answer 18

extravagant male morphologies means the male has passed the “test” and males without haven’t

“honest advertisement”

female preference for extreme morphology is therefore a preference for higher fitness males! WOW

Question 19

Tail Length

Answer 19

Test done showing females prefer the longest tail

Question 20

Runaway Sexual Selection

Answer 20

female choosiness and male elaboration form a positive feedback loop –> the females like long tales so males keep making their tails longer and longer

male appearance and fitness become de-coupled; extreme morphology NOT correlated with higher fitness

female’s choice NOT a guarantee of better genes for her offspring

Question 21

what are two basic kinds of reproductive modes?

Answer 21

copulation and spawning

Question 22

what HW requirement does sexual selection violate?

Answer 22

random mating!

demonstration of mate preference violates the random mating tenet of HW

AND that all offspring have an equal chance of survival and reproduction because if mate choice is based on heritable phenotype then some offspring will have a greater/lesser chance of reproducing

Question 23

what is viability?

Answer 23

probability that individual bearing genotype will survive

Question 24

what is mating success?

Answer 24

number and quality of mates

Question 25

what is fecundity?

Answer 25

number of gametes per individual

Question 26

what is segregation advantage?

Answer 26

alleles wind up in the games more/less frequently

Question 27

what is gamete viability?

Answer 27

alleles impact the longevity or quality of the egg or sperm

Question 28

what is fertilization success?

Answer 28

alles impact the probability that fertilization will take place

Question 29

why do females typically do the picking?

Answer 29

females produce the expensive gametes --> may also have post-mating responsibilities female strategy is typically focused on obtaining the best mate so that HER investment in eggs pays the greatest genetic dividend --> higher proportion of offspring survive and reproduce

Question 30

what kinds of things typically act as cues in female choice?

Answer 30

features that suggest health and capability in feeding features that emphasize distinction between males and females novelties that suggest that males are from another population

Question 31

what are costs associated with extreme morphologies?

Answer 31

plumage or antlers or complex songs require energy to make males bearing extreme trait are more conspicuous to predators so face a greater threat of being eaten but those males that survive despite this handicap have demonstrated their superior fitness