special reading - 1 - The adaptiveness of defence behaviour Flashcards Preview

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what were the hypotheses tested?

- a combination of eyes spots and sound (hissing) are more effective than either trait alone in the peacock butterflies predator defence


who wrote the paper?

Vallin et al (2005)


describe the treatment methods?

- 6 different treatments (3 treatment, 3 controls)
- treatment 1 - eye spots removed using marker pen ( control = marking parts of wing without eyespots)
- treatment 2 -hissing was removed by cutting lower edge of forewing (control = cut away lower edge of hindwing)
- treatment 3 - removed both (control = both)


How were the butterflies presented to the birds?

- presented in a small room with natural light to blue tits
- one on one
- studied 54 presentations
- bird discovered butterfly in all


what was the name of the butterfly and bird used in the experiment?

- peacock butterfly
- blue tit


what were the results of the study?

- eyespots significantly reduced predation risk - 9/9 survived vs 5/10 without eyespots
- hissing had no significant effect against blue tits
- 1/34 with eyespots were killed compared to 13/20 of those without


what do the results mean in reference to the hypothesis?

- for blue tits hissing isn't useful however it may be a useful predator defence strategy against other predators


describe the results of this test in context of other studies

- butterflies are exploiting the blue tits fear of large predators using eyespots
- dishonest signalling
- hissing whilst not effective has no costs


when undisturbed the butterflies adopt a cryptic position imitating a fallen leaf, however after being discovered and reacting(flicking wings open) they adopt one of 3 behaviours what are these?

1) keep eye spots visible
2) continue to flick wings in direction of bird
3) return to cryptic position


examples of anti predation techniques

- parents remove egg shells from nest
- dilution effect
- cryptic colouration e.g. dark moth (tested by operant conditioning in blue jays) e.g. decorator crab
- stotting (honest signalling)
- selfish herds

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