Adélie Penguins

Question 1

Sperm Competition

Answer 1

The competition between the sperm of two

or more males inside the female’s reproductive tract

Question 2

Male mallards mate guard to prevent their female copulating with an extra-pair male

Answer 2

If males can’t mate guard, timing and frequency of copulation will determine who gains paternity

Question 3

American Kestrel

Answer 3

Up to 690 copulations per clutch

Question 4

But do all behaviourally successful copulations result in sperm transfer?

Answer 4

Zebra Finches:
36% of copulations fail

Chickens:
50% of copulations fail

Question 5

Why would a male not transfer sperm when he had the chance?

Answer 5

So he can reserve sperm for extra pair copulations

Question 6

Fiona went to Antarctica New Zealand at Cape Bird.
300 thousand pairs of penguins. Long-lived, socially monogamous.
Adélie penguin’s main predator are arctic skuas.

Answer 6

They reclaim their last seasons mating site, do an ecstatic dance. Both species defend the nest. Female lays 2 eggs (+1 if an egg is lost). 10-12 days shift finding food. 35 days incubation. Then 1 day shift hunting krill.
The chicks gather in creches. Adults run the gauntlet at the ice edge where there are leopard seals.

Question 7

Fiona put flipper bands on the birds at pre-laying season. Males head-bow courtship.

Answer 7

If successful the cloacas come into contact.

Question 8

Recorded success and whether the male ejaculates. Can see the sperm on females cloaca.

Answer 8

Female will stay in laying down position, contracts her cloaca and draws the sperm inside.
Possible Outcomes:
An ejaculate enters the female’s cloaca
An ejaculate misses
No ejaculate is seen

Question 9

Fiona examined cloacal smears (inverted the cloaca to get the samples) then stained sperm to see if there is sperm transfer

Answer 9

If males are monogamous then they don’t compete for paternity. However, there are two sources of sperm competition: EPCs (9.8% females do it) and mate switching (14.9% females do it).

Question 10

Either sex initiates EPCs.

Answer 10

But the female has most control over copulation, as she can dislodge male or keep tail over cloaca

Question 11

Prostitution in Adélie penguins

Answer 11

Nesting sites are made of stones piled up. Will initiate EPC and then take a stone from his nest

Question 12

Possible Benefits of Prostitution Behaviour

Answer 12

Male benefits - extra offspring
potential mate

Female benefits - a source of stones
fertility assurance
good genes

Question 13

Sperm Competition is a real risk for pair males……so do they ensure insemination at every opportunity? Outcome of cloacal contact

Answer 13

57 attempts
42 cloacal contacts
25 inseminations

Outcome of cloacal contact
Ejaculate enters cloaca 59%
Ejaculate misses 18%
No ejaculate seen 23%

Question 14

Inter-ejaculate Interval

Answer 14

Should decrease with time:

Predicted pattern if responding to Sperm Competition

Question 15

Inter-ejaculate Interval

Answer 15

Should increase with time:

Predicted pattern if sperm is limited

Question 16

What might males do if sperm is limiting?

Answer 16

1. carry on copulating regardless

2. conserve sperm and allocate ejaculates strategically

Question 17

Zebra finches and house sparrows have limited sperm supplies

Answer 17

Sparrow resupplies sperm during night

Question 18

Prediction: If males allocate sperm strategically they will

Answer 18

prioritise EPCs over Pair Copulations

Question 19

By what mechanism could strategic allocation be achieved?

Answer 19

1. males attempt EPCs only when they have sperm available

2. males withhold ejaculates from their partners to conserve sperm

Question 20

Do pair males father the chicks they raise?

Answer 20

Extra-pair broods = 2.2% (n=46)Extra-pair chicks = 3.0% (n=67)

Question 21

Male Adélies have limited semen supplies

Answer 21

Males withhold ejaculates from their partners and strategically allocate them to extra-pair females

Pair males gain the most copulations and father the offspring they raise

Question 22

Males ter,inate pair mountings more than EPC mountings

Answer 22

But females disrupt EPCs more than pair copulations

Question 23

Males withhold sperm and allocate it to EPCs

Answer 23

But they could lose pair paternity, therefore only engage in EPCs after eggs have been laid