roz dakin & bob montgomerie eyespot colours 2 in species...

Examining P. cristatus courtship displays We measured eyespot colours of both species, and we modelled how females would perceive the contrast between adjacent colour patches under different light conditions using sensitivity curves for peacock cone photoreceptors. 25º 65º 45º relative sensitivity 0 1 300 400 600 700 wavelength (nm) 500 Peacock cone sensitivities (Hart 2002) 30 40 70 80 25° 45° 65° illumination angle contrast mixed models testing for a maximum at 45° n = 50 meaures of 10 P. cristatus feathers p = 0.57 p < 0.0001 p = 0.0008 e and contrasts are greater at angles closer to 45°. What is the effect of light angle? Displaying P. cristatus males orient their trains at 45° to the sun’s azimuth, on average. P. cristatus males display under light conditions that enhance the attractiveness of their eyespot plumage. 50 80 90 30 contrast 40 light conditions noon AM/PM p = 0.44 p = 0.001 p < 0.001 What is the effect of time of day? P. cristatus displays in the early morning and late afternoon. e contrast, which is important in mate choice, is greatest in the morning and late afternoon when courtship occurs. mixed models testing AM / PM vs. noon light n = 24 meaures of 12 P. cristatus feathers What is the effect of habitat light? P. cristatus displays in open habitats, whereas P. muticus lives in darker forest. 30 50 80 90 40 light conditions forest noon contrast e contrast, which is enhanced in P. muticus, is greater in the forest habitat of this species. Other contrasts are greater in open habitat light. mixed models testing noon light vs. forest light n = 20 measures of 10 P. cristatus feathers & 20 measures of 10 P. muticus feathers all p < 0.0001 P. cristatus P. muticus Habitat light conditions may explain the subtle species difference in eyespot colour. eir eyespots are very similar, especially the , , and patches. India blue peacock Pavo cristatus Java green peacock Pavo muticus t-test (n = 10, 10) brighter in P. muticus p < 0.0001 no difference in hue p = 0.18 brighter in P. muticus p < 0.0001 hue shifted to shorter λ p = 0.005 brighter in P. muticus p = 0.0006 hue shifted to longer λ p = 0.02 There are two peacock species with drastically different body colour. Eyespot colours Roz Dakin & Bob Montgomerie Queen’s University Canada 2 in species of peafowl But not identical. 300 400 600 700 wavelength λ (nm) % reflectance 0 50 100 Pavo cristatus Pavo muticus 500 References Mate choice for eyespot colour in P. cristatus Loyau et al. 2007. Behavioral Ecology 18: 1123-1131. Dakin and Montgomerie. See poster 256 next door. Submitted to J Evolutionary Biology. Peacock train displays and breeding habitat Dakin and Montgomerie. 2009. Behavioral Ecol Sociobiology 63: 825-834. Harikrishnan et al. 2010. Open Ornithology J. 3: 13-19. Brickle. 2002. Biological Conservation 105: 189-197. Modelling how females perceive eyespot colour contrasts Vorobyev and Osorio. 1998. Proceedings B 265: 351-358. Hart. 2002. J Experimental Biology 205: 3925-3935. Fig 7. Vorobyev et al. 1998. J Comp Physiology A 183: 621-633. Fig 3. Comparing Pavo species Overall, P. muticus has: more contrast, p = 0.0004 less contrast, p = 0.01 & no difference. p = 0.18 In P. cristatus, females prefer males with: brighter colour in the blue-green eyespot patch more contrast between blue-green & bronze 300 400 600 700 0 120 relative quantal flux AM / PM light noon light forest light (Vorobyev et al. 1998) wavelength (nm) 500 See our other poster 256 for details How does light affect their iridescent courtship signals?

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Page 1: Roz Dakin & Bob Montgomerie Eyespot colours 2 in species ...roslyndakin.com/wp-content/uploads/2012/07/DAKIN... · We measured eyespot colours of both species, and we modelled how

Examining P. cristatus courtship displays

We measured eyespot colours of both species, and we modelled how females would perceive the contrast between adjacent colour patches under di�erent light conditions using sensitivity curves for peacock cone photoreceptors.

25º

65º 45º

rela

tive

sens

itivi

300 400 600 700wavelength (nm)

500

Peacockcone sensitivities(Hart 2002)

25° 45° 65°

illumination angle

cont

rast

mixed models testingfor a maximum at 45°n = 50 meaures of 10P. cristatus feathers

p = 0.57 p < 0.0001 p = 0.0008

�e and contrasts are greater at angles closer to 45°.

What is the e�ect of light angle?Displaying P. cristatus males orient their trains at 45° to the sun’s azimuth, on average.

P. cristatus males display under light conditions that enhance the attractiveness

of their eyespot plumage.

cont

rast

light conditionsnoonAM/PM

p = 0.44 p = 0.001 p < 0.001

What is the e�ect of time of day?P. cristatus displays in the early morning and late afternoon.

�e contrast, which is important in mate choice, is greatest in the morning and late afternoon when courtship occurs.mixed models testingAM / PM vs. noon lightn = 24 meaures of 12P. cristatus feathers

What is the e�ect of habitat light?P. cristatus displays in open habitats, whereas P. muticus lives in darker forest.

light conditionsforestnoon

cont

rast

�e contrast, which is enhanced in P. muticus, is greater in the forest habitat of this species. Other contrasts are greater in open habitat light. mixed models testingnoon light vs. forest lightn = 20 measures of 10 P. cristatus feathers& 20 measures of 10 P. muticus feathers

all p < 0.0001

P. cristatusP. muticus

Habitat light conditions may explain the subtle species difference

in eyespot colour.

�eir eyespots are very similar,especially the , , and patches.

India blue peacockPavo cristatus

Java green peacockPavo muticus

t-test (n = 10, 10)

brighter in P. muticus p < 0.0001

no di�erence in hue p = 0.18

brighter in P. muticus p < 0.0001

hue shifted to shorter λ p = 0.005

brighter in P. muticus p = 0.0006

hue shifted to longer λ p = 0.02

There are two peacock specieswith drastically di�erent body colour.

Eyespot coloursRoz Dakin & Bob MontgomerieQueen’s University

Canada 2in speciesof peafowl

But not identical.

300 400 600 700wavelength λ (nm)

% re

flect

ance

100 Pavo cristatusPavo muticus

500

ReferencesMate choice for eyespot colour in P. cristatusLoyau et al. 2007. Behavioral Ecology 18: 1123-1131.Dakin and Montgomerie. See poster 256 next door.Submitted to J Evolutionary Biology.

Peacock train displays and breeding habitatDakin and Montgomerie. 2009. Behavioral Ecol Sociobiology 63: 825-834.Harikrishnan et al. 2010. Open Ornithology J. 3: 13-19.Brickle. 2002. Biological Conservation 105: 189-197.

Modelling how females perceive eyespot colour contrastsVorobyev and Osorio. 1998. Proceedings B 265: 351-358. Hart. 2002. J Experimental Biology 205: 3925-3935. Fig 7.Vorobyev et al. 1998. J Comp Physiology A 183: 621-633. Fig 3.

Comparing Pavo speciesOverall, P. muticus has:more contrast, p = 0.0004

less contrast, p = 0.01

& no di�erence. p = 0.18

In P. cristatus, females prefer males with: brighter colour in the blue-green eyespot patch more contrast between blue-green & bronze

300 400 600 7000

120

rela

tive

quan

tal f

lux

AM / PM lightnoon lightforest light