lecture 13 - sexual selection

Question 1

what is intrasexual selection

Answer 1

members of one sex complete with each other for access to other sex

Question 2

what is intersexual selection

Answer 2

individuals of one sex choose choose which individuals of other sex to take as mates

Question 3

what is bateman’s principle (1948)

Answer 3

females should be choosier sex bc eggs are expensive to produce and female potential reproductive success is limited compared to males. this choosiness should translate into greater variance in reproductive success of males so males should compete for females as mate

Question 4

are there stronger selection pressures in polygamous/polyandrous systems or monogamous systems

Answer 4

polygamous/polyandrous

Question 5

what are the evolutionary models of female mate choice broken into

Answer 5

• direct benefits
• good genes
• runaway selection
• sensory exploitation

Question 6

how can direct benefits affect mate choice/evolution

Answer 6

sexual selection favors females that have genetic predisposition to choose mates that provide them with tangible resources (more than sperm) that increase fecundity.

(females who choose males that give her food, shelter, help with parent care do better than less choosy females)

Question 7

how can fluctuating asymmetry affect mate choice

Answer 7

more symmetrical may mean better genes

Question 8

how can good genes affect mate choice/evolution

Answer 8

natural selection favored females that choose men with good genes (ex. genes associated with superior foraging/predator defense)

Question 9

how do female pronghorn antelopes choose mates and what evolutionary model is this

Answer 9

select mates that are better at defending harems of females which falls under good genes

Question 10

how does cost of trait relate to good genes

Answer 10

costlier traits means better genes

Question 11

how can runaway selection affect mate choice/evolution

Answer 11

When traits (like ones for good genes) are exaggerated excessively then the trait could lose control and it can be disadvantageous

Question 12

how can sensory bias affect mate choice/evolution

Answer 12

as a male trait first emerges it may be preferred bc elicit neurobiological response already in place in females even if the response has nothing to do with mating preferences (ex. birds like red berries bc they are better for them so when there is red feathers in males all of a sudden its selected for even tho they like red not for this reason)

Question 13

how does sensory bias model differ from the other models

Answer 13

designed to focus on emergence of mate choice instead of how natural selection acts on mate choice

Question 14

how do young individuals learn mating preferences

Answer 14

through sexual imprinting in which they learn what constitutes an appropriate mate from observing adults (usually parents)

Question 15

what is mate-choice copying

Answer 15

when female’s mate-choice preference affects preference of other females in population

Question 16

how does mate-choice copying work in black grouse

Answer 16

single male often obtains 80% of all matings at the lek where often the younger females copy the mate choice of older females

Question 17

how does male-male competition play in sexual selection in red deer roars

Answer 17

male red deer fight each other for females but they have indicators to determine how much time/energy to invest