Sexual Selection

Question 1

Some reasons why Why are so many species sexual dimorphic (3)

Answer 1

Ecological segregation (reduce competition between sexes)
Direct selection on traits important for reproduction 
Sexual selection (differences in mating success among individuals of same sex with diff traits)

Question 2

Root cause of sexual dimorphism and sexual selection

Answer 2

Anisogamy: trade off between gamete size and number means many small gametes and few large gametes (sperm and eggs)

Question 3

Lifetime reproductive success of females is limited by what

Answer 3

By number of eggs they can produce

Question 4

Males are limited by what

Answer 4

Number of females they can fertilize

Question 5

Bateman’s rule

Answer 5

Females should be choosy, males should be competitive

Question 6

What is intrasexual selection

Answer 6

Differential meeting success due to interactions among members of the same sex usually the sex that invests less

Question 7

How is intrasexual selection manifested (4)

Answer 7

1. Direct competition
2. Alternative mating strategies (ex sneaker males and mimics)
3. Sperm competition
4. Infanticide

Question 8

What is intersexual selection

Answer 8

Differences in mating success among members of one sex due to interactions with members of the other sex

Question 9

Evolution by Intersexual selection requires 4 things

Answer 9

1. Potential mates vary genetically in quality
2. Choosers can assess that variation
3. Choosing affects lifetime fitness
4. Heritability in choice among the choosers

But can be arbitrary because choice has to affect fitness but the trait chosen for doesn’t have to affect fitness

Question 10

What causes a correlated response

Answer 10

Drift or selection

Question 11

Sensory exploitation

Answer 11

There is a pre-existing sensory by us for treats that the choices are based on males will evolve to fit the females constraints

Question 12

Choice can be based on resources such as (3)

Answer 12

• food (cannibalism my dude)
• parental care (can lead to mutual sexual selection like in humansss)
• good genes (disease resistance -natural selection, or sexy sons - sexual selection)