Sexual selection

Question 1

Darwin’s theory

Answer 1

Proposed that sexual selection is a form of natural selection - selection of traits that increases mating success

Question 2

Why are females picky with mates?

Answer 2

Females have fewer eggs (than males have sperm) - so can’t afford to “waste” any on mating with unworthy males
- also carry young, give birth, lactate etc

Question 3

Do males have greater reproductive potential than females?

Answer 3

yes, they can father more offspring

Question 4

why does sexual selection rise?

Answer 4

males compete for females whose eggs are a scarce resource. this leads to males competing more males

Question 5

Intrasexual selection

Answer 5

direct male to male combat. however, a fight will only occur if both males are a similar size/strength.

Question 6

Intersexual selection

Answer 6

Females prefer to mate with males who have an exaggerated form of male trait

Question 7

What impact does the environment have on mate choice?

Answer 7

• sound (vocalisations) can be used to attract mates - need to be loud to hear over noise pollution in city
• sunlight (make peacocks will angle feathers towards sun to be more attractive)

Question 8

Strategies for mating

Answer 8

• courtship / nuptial gifts
• displays (peacock tails)
• aggressive competition
• sperm competition

Question 9

Example of courtship feeding / nuptial gifts

Answer 9

Male spiders will bring food to the female to say they want to mate

Question 10

examples of Courtship displays

Answer 10

• peacocks will show off their feathers

Question 11

Sperm competition

Answer 11

• competition between sperm from rival males to fertilise egg
• sometimes mate guards female to prevent further mating
• copulatory plugs (stick insects and guinea pigs. plugs prevent mating)