Lecture 8 - research seminar - Adelie penguins Flashcards Preview

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Flashcards in Lecture 8 - research seminar - Adelie penguins Deck (23)
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1
Q

what happens if males cant mate guard?

A

timing and frequency of copulation will determine who gains paternity

2
Q

what can be studies to determine copulation frequency?

A

cloacal contact

3
Q

how do American kestrels mate?

A
  • the males fail to mate guard due to a large proportion of their time being spent hunting
  • to compensate for this the males copulate up to 690 times per clutch
4
Q

do all copulations result in sperm transfer?

A
  • no all behaviourally successful copulation result in sperm transfer - making them invalid
  • zebra finches = 36% of copulations fail
  • chickens - 50% copulations fail
5
Q

what was the basis of the adelie penguin study?

A
  • they carry out up to 57 copulations but not all are successful and they wanted to know why
6
Q

where was the study carried out?

A

cape bird - Antarctica - 300,000 penguins breed here - the nest on ridges

7
Q

describe the breeding strategy of the penguins

A

socially monogamous sea birds - the males set up the nest first and when the females arrive they up with their partners from the previous year
- the female lays 2 eggs and will lay a 3rd if one is lost

8
Q

describe parental investment of the penguins

A
  • both of them protect the nest from predators such as the antarctic Skua
  • they swap turns incubating for a period of days while the other hunts
  • once this chick is born they swap daily bringing krill to the nest
9
Q

what happens when the chick is 2-3 weeks old

A

the chicks need more food so both parents go out to hunt and all the chicks huddle together in a creche

10
Q

explain the field work for the experiment

A
  • they observed about 50 pairs copulations (roughly 10,000 copulations throughout the breeding season)
  • each copulation attempt and outcome was recorded
  • can observe the ejaculate on the females cloaca - the females rhythmically contract their cloaca therefore you are able to record a successful sperm transfer
11
Q

what were the 3 possible outcomes after the observed copulations?

A

1) an ejaculate enters the females cloaca
2) An ejaculate misses
3) No ejaculate is seen

12
Q

how did they examine the sperm?

A
  • examined cloacal smears from females of each of the 3 categories
  • stained sperm to head fluoresced
  • look under fluorescent microscope to record presence of absence of sperm
13
Q

what are 2 sources of sperm competition in adelie penguins

A

1) extra pair copulations - 9.8% of females took part in this
2) mate switching - copulates with single male and then switches to a male that she is paired with and will help her raise her chick - 14.9%

14
Q

which sex initiated EPCs?

A

it was demonstrated that either sex would initate epcs however forced epcs by males were never successful - the females had control

15
Q

describe prositution in the adelies

A
  • some females would exchange epcs for nest material
  • they build their nests from stones which are in great demand
  • males benefit by giving stones because they can father extra offspring they dont need to care for
  • females benefit by a source of stones and fertility assurance
16
Q

half of copulation attempts end in failure what are 6reasons for this?

A

1) no sperm deposited
2) sperm missed cloaca
3) male dismounts
4) male falls off
5) female throws male off
6) disturbed by neighbour

17
Q

in nearly 1/4 of copulation the male doesnt ejaculate what is a predicted reason for this?

A

limited semen supplies - this was proven by overall ejaculate increasing in the time before breeding season i.e. sperm is limited

18
Q

2 strategies males will limied sperm might do?

A

1) carry on copulating regardless

2) conserve sperm and allocate ejaculates strategically

19
Q

why do adelie penguins have limited time to replenish sperm?

A

there is no night time when other birds such as zebra finches would normally replenish sperm

20
Q

what was the main prediction of the experiment for males with limited sperm supplies?

A

if males allocate sperm strategically they will prioritise EPCs over pair copulations - this is because males arent guaranteed another EPC but they can copulate multiple times with their partner

21
Q

by what mechanisms can strategic allocation be achieved?

A

1) males attempt EPCs only when they have sperm available

2) males withhold ejaculates from their partners to conserve sperm

22
Q

what do the results from the investigation show about strategic allocation?

A
  • males strategically allocate ejaculates to EPCs
  • males that engage in EPCs had fewer cloacal contacts
  • males are withholding ejaculates from their partner and strategically allocating to EPCs
23
Q

do pair males father the chicks they raise?

A
  • adelies are synchronus breeders - so EPCs have to take place during breeding season - could risk paternity of pairs offspring
  • results showed paired males gained statistically more success in copulations and higher frequency in them
  • proves that increased frequency of copulations ub the pairs does make up for EPCs
  • still worth it for the male to have a go at gaining an EPC because they are still able to outcompete rival males by copulating more than them

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