Adelie penguin case study

Question 1

Adelie’s are monogamous, what is mate switching?

Answer 1

• If male from previous year doesn’t return,
• Female chooses nearest male but will switch back to original male if he returns.

Question 2

It is possible for researchers to tell when an ejeculate has been succesful, what are the possible outcomes of copulations?

Answer 2

1. An ejaculate enters the female’s cloaca
2. An ejaculate misses
3. No ejaculate is seen

Question 3

What is a Cloacal smear?

Answer 3

A way to see if sperm has entered even if ejaculate isn’t seen being drawn into female’s cloaca

Question 4

What is meant by prostitution in the penguins?

Answer 4

• Stones are valuable because larger nests will protect against melt water that flows through the colony during spring.
• Females engage in prostitution - paid in stones - successful extra pair copulations.

Question 5

What are the benefits of the extra-pair matings (prostitution)?

Answer 5

• Male benefits by gaining extra offspring for which he doesn’t have to care for
• Females benefits - source of stones, fertility assurance, good genes.

Question 6

During mating season male seamen is limited

Answer 6

• Males need to replenish stocks before next ejaculate
• Interjaculate intervals increase over the pre-laying period
• Sperm and/or seminal fluid is limiting for Adelie penguins

Question 7

Do males allocate sperm strategically?

Answer 7

• Males almost always manage to produce an ejaculate when with an extra pair over their pair
• Females terminated more extra pair copulations

Question 8

Benefits of gaining extra-pair copulations are so high that they’ll give it a go anyways

Answer 8

• Male Adélies have limited semen supplies
• 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