Sexual Selection

Question 1

Reverse anisogamy examples

Answer 1

Male crickets provide a nuptial gift (25% of body mass) as a result can’t mate more than once -
Become choosy of who to mate with

Skinny Australian katydid produce a costly spermatophore and during limited food supply, the males become higher value and as a result more choosy

(Alcock 2005)

Question 2

Varying preference for male trait

Answer 2

Sticklebacks - female os inherit trait preference and male os inherit trait

Question 3

Sensory biases for male traits

Answer 3

Tungara frogs: females prefer males with whines and chucks - ancestors preferred this before chuck evolved

Female bowerbirds eat certain fruit colours - the same colours are used by males for decoration of nest

Question 4

Good gene indicators in trait preference by female examples

Answer 4

Bowerbird courtship structure may indicate a well constructed brain (Alcock 2005)

Carotenoids in zebra finches are a good indicator of foraging ability and immune function in zebra finches (Alcock 2005)

Question 5

Genetic comparability examples

Answer 5

Female Japanese quail prefer males of intermediate relatedness

Major histocompatability complex (group of genes involved in immune function) - female lab mice prefer males that will increase heterozygosity of their offspring

Question 6

Webers law example

Answer 6

Female tungara frogs find it hard to discriminate between males that have a larger number of chucks

Question 7

Anisogamy examples

Answer 7

Hens and roosters - costly egg gamete production results in hens being choosy and roosters going for number of copulations