Sexual Selection

Question 1

What is intersexual selection

Answer 1

Individuals of the same sex choose a mate

Question 2

What is Bateman’s principle

Answer 2

Women are the choosier sex because eggs are more costly to produce than sperm and their reproductive success is limited

Question 3

What are 2 learning models of intersexual selection

Answer 3

1. Classical conditioning - Japanese quail learn to stay in areas where there are lots of females
2. Imprinting - learn mating preferences from adult interactions. Humans chose a mate similar to their opposite sex parent

Question 4

What are 2 cultural transmission models of intersexual selection

Answer 4

1. Mate choice copying - female mate choice is affected by other females. Grouse males are more likely to mate if they have recently mates
2. Song learning - birds learn songs from others. Cowbirds prefer songs of the birds they were raised with

Question 5

What are the 4 evolutionary models of intersexual selection

Answer 5

1. Direct benefits
2. Good genes
3. Sensory bias
4. Runaway selection

Question 6

Give an example of direct benefits

Answer 6

Nuptial gifts
E.g Scorpionfly - chose the male that brings the largest prey. Copulate longer the larger the prey. Direct benefits of food. Dangerous for males and time consuming to catch prey

Question 7

Give 2 examples of good genes as an evolutionary model of intersexual selection

Answer 7

1. MHC - prefer mates with dissimilar MHC genes e.g humans prefer the smell of mates with dissimilar MHC
2. Pronghorn antelope - harem defence is a sign of good genes. Better they defend the harem, more likely to mate

Question 8

Give an example of sensory bias as an evolutionary model of intersexual selection

Answer 8

Primates - as a male trait emerges it may be preferred if it elicits a neurobiological response. Primate males have red faces and they eat red fruit. More attracted to red things

Question 9

Give an example of runaway selection as an evolutionary model of intersexual selection

Answer 9

E.g stalk eyed flies - prefer males with eyes on long stalks. In their genes

Question 10

What is intrasexual selection

Answer 10

Members of one sex compete with each other for access to mates

Question 11

Give 2 factors of male male competition

Answer 11

1. Interference

2. Cuckoldry

Question 12

Give an example of male male competition

Answer 12

Red deer
Roar is an indicator of strength
If roar is stronger than the other they are less likely to fight

Question 13

Give an example of interference

Answer 13

Elephant seals
Females protest at mating attempts with subordinate males
Larger the harem, bigger the males and more male male competition

Question 14

Give an example of cuckoldry

Answer 14

Blue gill sunfish
1. Parental morphs - build nests and look after babies. Less but higher quality sperm

2. Sneaker morphs - hide and shed sperm in to parental male territory. More but lower quality sperm
3. Satellite morphs - look like females and position themselves between a mating couple