Sexual Selection 2

Question 1

why do females choose on bizarre traits?

Answer 1

females just have biases - adaptive preference - gain through choice of male

Question 2

are traits arbitary?

Answer 2

first real theory - fishers runaway process

- mutations suggest females like males w/ long tails best still benefit females as more with long tails in next gen

Question 3

what did fisher believe?

Answer 3

females had arbitrary preferences, the advantage of having them could result in ‘runaway’ processs increasing frequency of traits and preferences in a pop

Question 4

are traits adaptive?

Answer 4

look at resource based mating system
a sexually dimorphic male will provide territory, food and even feed the female - indicates his quality
dance flies give nupital gifts -but they can cheat e.g swap it for cotton wool

Question 5

what is a lek?

Answer 5

females don’t seem to get much back but still exercise care choosing
watch and choose a male then mate, get inseminated and leave and do everything else herself

Question 6

are females choosing males with good genes?

Answer 6

handicap process - females should choose odd traits so poor quality males can’t cheat - e.g antlers in deer if they can survive with it then they must be strong
odd traits are like advertisements

Question 7

?what does the handicap method involves

Answer 7

implies traits provide honest signals of male quality
traits should be expensive and deleterious
male with best genotype will have the biggest handicap
trait expression should be condition- dependent

Question 8

why was the handicap method criticised?

Answer 8

hard to prove unambigously

hard to show its not direct result of maternal/paternal reproductive effort

Question 9

what happens if females are allowed to choose their mate?

Answer 9

they have offspring with higher viability

Question 10

what does the experiment with barn swallows tell us?

Answer 10

that as after tail feather manip
those with longest tails chosen first - influenced the number of fledlings and had carryon effect for next gen
when parasites added
- long tail is energetically expensive but theres genetic variability in ‘quality’ in the ability to resist parasites

Question 11

what happens when you add parasite to barn swallow eggs?

Answer 11

co-evolution maintains genetic variation - parasitism and extent of sexual dimorphism - have males with higher than average prevalence of parasites