Evolutionary explanations- sexual selection

Question 1

who proposed the theory of natural selection

Answer 1

Charles Darwin proposed the theory of natural selection- which is the idea that if an animal possess desirable characteristics that enhance its survival, it will continue in future generations

Question 2

what is sexual selection

Answer 2

Sexual selection is an evolutionary explanation of partner preference,
- attributes or behaviours that increase reproductive success are passed on to future generations and become more exaggerated over succeeding generations

Question 3

what does anisogamy

Answer 3

the differences between male and female sex cells

Question 4

describe male gametes (sperm)

Answer 4

-small
-can move/ swim
- vast numbers until old age
- not much energy required

Question 5

describe female gametes (ova)

Answer 5

• large
• cannot move independently
• limited number/ will run out
• requires lots of energy to produce

Question 6

what is inter-sexual selection?

Answer 6

• Females selecting a mate based on specific traits
• Trivers argues that females are more choosy when it comes to mating
  This done because:
• it requires more energy to produce an egg
• historically females invest more time/commitment to raising their offspring

Question 7

what is the runaway process?

Answer 7

• female preference determines which features are passed onto the offspring
• this trait will become more exaggerated over time because it is preferred by the opposite sex
• eg if a woman prefers tall males, overtime they would produce sons that are taller and daughters who prefer tall partners

Question 8

what is Fisher’s sexy son hypothesis?

Answer 8

• a female who mates with a male who has a desirable characteristic, then will have sons who inherit this ‘sexy trait’
• the sons are now more likely to mate successfully therefore the ‘sexy’ trait continues to be passed on

Question 9

what is intra-sexual selection?

Answer 9

• males compete in order to reproduce
• the winner passes down the characteristics that contributed to his victory
• dimorphism: physical differences between males and females. eg males need to be larger to defeat rivals
• the optimum reproductive strategy for men is to mate with as many fertile females as possible

Question 10

A03: what is the research supporting partner preference?

Answer 10

P: There is evidence supporting the specific role of female choosiness in partner preference
EE: Clark and Hatfield (1989) sent a male and female psychology student across a university campus and approached other students with this question ‘‘I have been noticing you around campus. I find you very attractive. Would like to go to bed with me tonight?’’
- 0% of women said yes
- 75% of men said yes
L: This supports the view that females are choosier than males when it comes to selecting sexual partners and that males have evolved a different strategy to ensure reproductive success

Question 11

A03: what is the research supporting sexual selection?

Answer 11

P: There is evidence to support sexual selection
EE: Buss carried out a survey of over 10,000 adults in 33 countries. He asked questions about attributes that evolutionary theory predicts are important to partner preference. He found that women prefer resource related characteristics, and men vale physical attractiveness and youth
L: This reflects sex differences in male and female reproductive strategies due to anisogamy

Question 12

A03: social and cultural influences underestimated

Answer 12

P: The evolutionary theory overlooks cultural influences on partner preference.
EE: Bereczkei el al argues that women may no longer be resource oriented due to the fact that they can now work so don’t need men to provide.
The theory less relevant due to increase in availability of contraception. The theory does not apply to same sex couples
L: Therefore, partner preference today are likely to be the outcome of a combination of evolutionary and cultural influences. Any theory that fails to account for both is a limited explanation