lecture 16

Question 1

Sexual dimorphism

Answer 1

differences in phenotype between males and females of the same species as result of differences in genetic material; ex. in humans, males are on average taller than females

Question 2

sexual selection

Answer 2

selection for phenotypes that may reduce survival, but that increase mating success; ex. Peacock’s elaborate tail, which greatly impairs mobility

Question 3

intra-sexual selection

Answer 3

mating success determined by within sex interaction; ex. male-male combat

Question 4

inter-sexual selection (epigamic selection)

Answer 4

mating success determined by between sex interactions; ex. female choice of males

Question 5

Fecundity selection

Answer 5

selection on female fecundity (number of offspring produced); different than mating success (number of mates); larger females can produce more eggs which increases reproductive fitness

Question 6

Sexual vs. natural selection in marine iguanas

Answer 6

large males are more successful at attracting mates and so sexual selection favors large males; but there is a cost of large size in El Nino years where food is scarce and unable to meet energy demands

Question 7

anisogamy

Answer 7

form of sexual reproduction involving the union or fusion of two dissimilar gametes (rather than two isogametes); ex. large immobile egg and small mobile sperm

Question 8

Bateman’s principle and experiments

Answer 8

greater variance in reproductive success among males than females; males have greater success as number of mates increases, but females are just as successful with one mate (success not increased with multiple mates); males are limited by number of females and females are limited by resources and good genes

Question 9

rough skinned newts

Answer 9

when males had increased number of mates, produced much more offspring; females barely increased number of offspring when more matings

Question 10

male combat in red deer

Answer 10

reproductive success is more variable in males than females; some males don’t produce any offspring while some have over 20 offspring

Question 11

broad nosed pipefish

Answer 11

females compete for access to males and access to their pouches; males are investing the most and so they have less variance in mating success than females; an example of role-reversed species

Question 12

Conditional mating strategies

Answer 12

alternative phenotypes expressed by low ranking individuals to try to make the most of a bad situation against the more dominant ones; doesn’t generally have the same fitness between tactics

Question 13

Dominance behavior in elephant seals

Answer 13

males who are more dominant are getting more mating opportunities

Question 14

Dominance behavior (monkeys?)

Answer 14

alpha males are getting more mating opportunities and mate in the open; subordinates get less and mate in a hidden place

Question 15

Enthusiasm and the Coolidge effect

Answer 15

used to keep chickens on whitehouse lawn and there was only one rooster who mated with all of the females; rooster will have enthusiasm each time because presented with different female; when presented with a new mating partner, more likely to take part in a mating activity and less time in between mating activities

Question 16

Mate guarding in frogs

Answer 16

males jump on females’ backs and females have to carry male for extended period of time to prevent her from mating with anyone else and ensure that his sperm is fertilizing her eggs

Question 17

sperm competition

Answer 17

sperm from some males have greater chance of fertilizing eggs than others, may be due to different amounts of sperm ejaculated or displacement or inactivation of rivals’ sperm

Question 18

sperm competition in fruit flies

Answer 18

male fruit flies were reared alone or with another male, and then were allowed to mate with female; males in presence of other males produced 2.5 times more sperm than males reared alone

Question 19

Black winged damselflies and sperm competition

Answer 19

scoop out previous male’s sperm before mating

Question 20

Ghost spider crab- sperm competition

Answer 20

release a secretion that cements around another male’s sperm, preventing it from fertilizing egg

Question 21

cabbage white butterfly

Answer 21

after mating, males leave behind chemical repellents that stink and other males find repulsive so other males wont want to mate with female

Question 22

red-sided garter snakes

Answer 22

after males mate, they create a plug that renders the female unattractive to other males; male bees use a similar process to make female bees unattractive