Sexual selection

Question 1

What are the different types of mating systems?

Answer 1

• Polygamy: everyone has multiple mates
• Polyandry: females have multiple mates
• Polygyny: Males have multiple mates
• Monogamy: Long standing pair bonds between individuals

Question 2

What is sexual dimorphism?

Answer 2

Differences between males and females e.g. lions have manes whereas female lions don’t

Question 3

What is intra-sexual competition?

Answer 3

• Within-sex competitions
• Typically, males compete for access to females e.g. elephant seal males fighting to be beach master and gain access to the females

Question 4

What is inter-sexual competition

Answer 4

• One sex tries to attract the other with ornaments and displays
• Females do the choosing e.g. bird mating dances

Question 5

Why do females do the choosing?

Parental investment theory (Robert Trivers, 1972)

Answer 5

Female costs:

• Limited supply of eggs
• 9 months of gestation
• Dangerous birth
• Lactation
• Years of child rearing
• Feeding
• Very costly investment

Male costs:

• One orgasm
• Minimal investment

Females pay a high price for mistakes (or males if they rear the child)

Question 6

What is Zahavi’s handicap principle?

Answer 6

• Only the ‘fittest’ individuals can grow ornaments
• The more someone spends, the more they have
• Can reduce fitness of species –> high cost handicap means reduced fitness
• Waste is necessary –> ornaments cannot be faked

Question 7

What is the mating mind hypothesis?

Answer 7

• Miller (2003) suggests runaway sexual selection is the answer
• Preference for intelligence and creativity
• Reproduction with most creative
• Heritability of creativity
• Positive feedback loop
• Lack of dimorphism in intelligence suggests:
  1. Mutual mate choice
• Cre