Sexual selection

Question 1

nature red in tooth and claw

Answer 1

-surviving to breed or dying before able to reproduce

Question 2

unit of selection=

Answer 2

gene

Question 3

mating behaviour - ‘lek’

Answer 3

-males aggregate at a ‘lek’ site during breeding season and strut about - claiming territory

Question 4

sexual dimorphism

Answer 4

differences between the sexes

Question 5

reasons for different breeding/social systems and life history strategies

Answer 5

• polygamy (polygyny/polyandry) vs monogomy
• few offspring vs many offspring
• maturation rate

Question 6

mating success

Answer 6

intersexual selection

-persuasion of opposite sex to breed

Question 7

competition for mates

Answer 7

itrasexual selection

-fend off members of same sex to prevent matings

Question 8

Investment in gametes and offspring is different for males and females:

Answer 8

• males (heterogametic) contribute nothing but sperm

- females (homogametic) costly reproductive effort

Question 9

‘choosy females’

Answer 9

• letting just any male mate will reduce average fitness of her offspring
• his genes could be sub-optimal
• therefore she goes for the best (highest fitness) she can find

Question 10

Polygyny

Answer 10

• males seek any mates and don’t care

e. g. red deer, elephant seals

Question 11

Polyandry

Answer 11

• females seek many mates and don’t care

e. g. phalaropes

Question 12

Polygynous males - why much larger than females

Answer 12

• breeding success requires that he can win harem from another male, attract females, keep intact, fend off incursions
• strategy - alleles are selected that act in males to enhance physiological adaptations, size etc
• behavioural adaptations

Question 13

Side blotched lizards male polymorphism is an example of:

Answer 13

-balancing selection underlain by frequency-dependent selection

Question 14

Kin selection

Answer 14

evolution of behaviour that promotes reproduction by your relatives
e.g. protecting relatives from predation –> altruism?

Question 15

kin selection

Answer 15

• evolution of cooperation and competition to maximise LRS
• evolves according to ‘game theory’
• an evolutionary stable strategy ESS

Question 16

eusocial insects

Answer 16

-worker sacrifice right to breed
-haploploidy
-means workers are more closely related to each other than to their own diploid offspring
-

Question 17

reciprocal altruism

Answer 17

-adults vampire bats share blood meals on return to roost

Question 18

sensory bias

Answer 18

-female preference may have pre-existed , preferred train in males comes later and is selected due to ‘inbuilt’ female preference

Question 19

Indirect selection:

Answer 19

preference in female (or choosy sex) indirectly selected via direct selection on preferred male (non choosy sex) trait

Question 20

‘runaway selection’

Answer 20

• Fisher 1915
• both trait and preference
• assortative mating
• their offspring are likely to carry both trait gene and pref. gene