Sexual Selection

Question 1

What is Darwins theory?

Answer 1

• Proposed that sexual selection is a form of natural selection
• Suggested sexual selection was the selection of traits that increase mating success

Question 2

What is intRAsexual selection?

Answer 2

• Direct male to male competition and combat
• Often leads to development of secondary sexual characteristics - a male adornment such as antlers to help fight off competitors

Question 3

What is intERsexual selection?

Answer 3

• Where females choose members of the opposite sex
• Typically go with males with exaggerated form of a male trait e.g. female peacocks will go for the male with the most impressive tail feather as indication of better genes.

Question 4

What is the case study for intERsexual selection?

Answer 4

• By Darwin
• In the presence of a predator, the female sword tail fish prefer males with shorter tails
• Females typically prefer longer tails in usual circumstances because it shows they have a lot more nutrients to grow longer tails.

Question 5

What is nuptial gifts?

Answer 5

• Presenting the female with gifts to get her to mate
• Can be food, nests or territory

Question 6

What are adornments?

Answer 6

• Ornaments owned by the males to demonstrate good genetic quality
• e.g. peacocks tails, costly to produce pigments and regrow feathers

Question 7

What are sneaky copulations?

Answer 7

• When subordinate males in a hierarchy steal copulations while the alpha male is busy
• Promotes diversity in the groups gene pool

Question 8

What is sperm competition?

Answer 8

• When the female mates with numerous males and is the competition of whos gets to the egg first
• The more sperm, the better chance of success - females look for bigger testes for this

Question 9

What are copulatory plugs?

Answer 9

• A secretion from the male to prevent sperm leaking out the female to promote success of fertilisation
• Doesnt prevent the female from mating a second time with a different male

Question 10

What are the benefits to females mating numerous times?

Answer 10

• Ensures fertilisation occurs
• Increased protection from numerous males
• Gains food through nuptial gifts

Question 11

What are courtship displays?

Answer 11

• Set of behaviours performed by a male to attract females
• Can be visual, vocal

Question 12

What is asymmetry?

Answer 12

• The female invests more time into reproduction that males
• They have fewer eggs so cant waste any mating with unworthy males
• They carry the young, give birth, lactate (mammals) and provide the majority of the parental care

Question 13

What is mate guarding?

Answer 13

Males physically guard the female to prevent her mating with others to improve the odds of their sperm going forward

Question 14

What is fishers runaway?

Answer 14

• Created by Fisher
• Mechanism where a secondary sexual trait shown in one sex becomes genetically correlated with a preference for the trait in the other sex

Question 15

What is the parasite hypothesis?

Answer 15

• Created by Hamilton and Zuk
• Suggests a males showiness allows females to assess the males ability to resist parasites

Question 16

What is the handicap principle?

Answer 16

• By Zahavi
• Suggests that females favour males with a trait that reduces the chance for survival
• E.G. peacocks tail, reduces its ability to run from predators but shows a good gene pool