Reproductive Behaviour

Question 1

What is the ancestral state of gametes?

Answer 1

Equal sized gametes

Question 2

What is sperm competition?

Answer 2

Competition between the sperm of two or more males inside the female’s reproductive tract

Question 3

How do some males outcompete rivals?

Answer 3

Male damselflies remove sperm of rivals

Polyandrous males produce higher proportion of viable sperm than monogomous males

Question 4

How do some males protect their paternity? What is the evidence for this?

Answer 4

Mate guarding

Seychelles Warblers:

• males mate guard during the fertile period and stop when the female lays her egg
• when no fake egg is added to the nest there are very few intrusions due to him mate guarding
• when a fake egg is added to the nest the male no longer mate guards and the amount of intrusions and successful extra pair copulations increase

Frequent copulation:

• seen in male fulmars
• copulate 50 times with partner
• ensures optimal timing of insemination relative to fertilisation

Question 5

How do Milkweed beetles mate guard?

Answer 5

Remove mate guarding males from females

25% of separated males found a new mate within 30 minutes so guarding results in missed mating opportunities

50% of females found a new mate after male removal and so guarding prevents female from remating

Question 6

What is cryptic female choice?

Answer 6

Female manipulates sperm inside of her reproductive tract so that a preferred male fertilises her eggs

Question 7

Give some examples of sperm ejection

Answer 7

A form of cryptic female choice

Domestic fowl:

• females eject sperm of subordinate males and accept sperm of dominant males

Dunnocks:

• male pecks at female cloaca to see if another male has mated with her
• she may eject a droplet of fluid containing sperm but the sperm is not viable

Question 8

How do male hanging flies mate with females?

Answer 8

Give a nuptial gift to the female

Whilst she is snacking the male mates and transfers sperm

Question 9

Why do females engage in female choice/cryptic female choice?

Answer 9

Females may gain:

1) Higher quality offspring - by choosing higher quality fathers

2) More offspring - by choice of genetically compatible males

Question 10

What are two alternative mating tactics?

Answer 10

1) Alternatives are not equally rewarding - best of a bad job

2) Alternatives that are equally rewarding

Question 11

What are the different male tactics in scorpian flies? Do they have equal fitness?

Answer 11

Large males:

• guard dead insects attractive to females

Medium-sized males:

• produce salivary gifts to attract females

Small males:

• force copulation of females

Do not have equal fitness - larger males have many more copulations than smaller males