Reading 4.2 Pryke

Question 1

The hypotheses tested (2)

Answer 1

• Test for adaptive female participation in extra-pair copulations
  • To test the potential additive genetic benefits provided by extra-pair males in socially monogamous females, through post-copulatory behaviour

Question 2

The methods

Answer 2

• Study was performed on Gouldian Finches
• socially monogamous birds
• On the day after female-initiated egg laying day social pair birds were physically and visually separated by an opaque divider
  • A virgin male was placed with the female for 60 mins
  • Varying compatibilities with the female

Question 3

How long was a virgin male placed with the female for?

Answer 3

60 minutes

Question 4

What types of male were there?

Answer 4

Varying compatibilities with female

Question 5

How were male and female divided?

Answer 5

Physically and visually by an opaque divider

Question 6

Results

Answer 6

• Females across all conditions engaged in extra pair behaviour
  • 31/40 males copulated with the extra pair male
  • Active female solicitation of copulation
  • Males displayed in 95% of the trials 38/40
  • Displays did not discriminate between female compatibility
  • The paradox is that despite females partaking in EPCs , this still is costly to her and also can jeopardize the investment provided by the social partner (as it is not his offspring)
  • Females cannot distinguish between genotypically different morphs

Question 7

How many females copulated with the extra pair male?

Answer 7

31/40

Question 8

How many trials did males display in?

Answer 8

38/40 95% of trials

Question 9

Why is partaking in EPCs costly to a female?

Answer 9

It can jeopardize investment provided by the social partner (as it is not his offspring)

Question 10

Experiment 2 tested:

Answer 10

The potential for postcopulatory sexual selection

Question 11

Experiment 2 results:

Answer 11

• Extra-pair males gained disproportionate fertilisation success 24 to 48 hours after copulating just once
  • Even though once reunited with the social pair copulation ensued
  • Females copulated less with incompatible social mates than with compatible partners
  • Gouldian finch females seeking EPCs may ensure fertilisation of their eggs by a compatible male and produce more viable offspring
  • Extra pair copulations with compatible males results in 38.9% increase in offspring survival compared to females forced to mate exclusively with their genetically incompatible social mates

Question 12

To the study of animal behaviour as a whole.

Answer 12

-To understand the evolution of female polyandry in socially monogamous animals, we need to account for both pre- and postcopulatory processes.

-Our results suggest that neglecting these details may underestimate the extent of behavioral infidelity and the potential adaptive benefits to
females