Bovesfwf.ag.utk.edu/mgray/wfs512/SeminarFA11/Boves.pdf10/31/2011 1 Than J. Boves Department of...
Transcript of Bovesfwf.ag.utk.edu/mgray/wfs512/SeminarFA11/Boves.pdf10/31/2011 1 Than J. Boves Department of...
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Than J. BovesDepartment of Forestry, Wildlife, and FisheriesUniversity of Tennessee, Knoxville
26 October 201112:20 PM, PBB 160
Theory of honest signals –to provide reliable information about the quality of an individual q y(Darwin 1871 , Andersson 1994)
Typically males display and compete; females choose
Males of many species display multiple plumage ornaments (Møller and Pomianski 1993)
1) Send multiple messages (about different qualities),
2) Send redundant messages (about overall quality), or
3) Because females simply prefer some plumage traits (via runaway selection)(via runaway selection)
Several mechanisms may allow for multiple messages:
a) Plumage ornaments of different metabolic origin may reflect different intrinsic (production) or extrinsic (social) costs to the individual (Searcy and Nowicki 2005)
b) Environmental/habitat contingency; environmental conditions may render some signals more effective(Roulin et al. 2008)
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Any phenotypic or genotypic trait directly related to individual fitness (i.e., survival or reproduction) (Wilson and Nussey 2010)( y )
Measures of individual quality could include:
Body condition Foraging ability # of fledglings produced Immunocompetance Age/survival
Can be created by pigments, physical structure, or a combination (Hill and McGraw 2006)
Carotenoids – producereds, yellows, and greens
Melanins – produce black, gray, brown, buff, and some yellows
Structural – produce blues, some greens, iridescence and glossiness (and whites)
May signal quality in relation to:
1) Size of feather patch (Senar 2006)
2) Color variables of feather patch ( 6)(Montgomerie 2006)
a) Brightness –Total reflectance
b) Hue –Wavelength of peak reflectance
c) Chroma – Proportion of reflectance located in a specific region (e.g., Blue‐Green) of the color spectrum
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15
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300 330 360 390 420 450 480 510 540 570 600 630 660 690
% R
efle
ctan
ce
Wavelength (nm)
Hue
Chroma
Brightness
UV
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1) Do Cerulean Warbler plumage ornaments act as honest indicators of quality? If so, do they send multiple messages or redundant messages?
2) Does habitat heterogeneity impact information content of ornaments (and if so, how)?
3) Do birds that display differential elaboration of plumage ornaments inhabit different habitats?
Canopy‐dwelling species with unique plumage which occupies unique light environment (Théry 2006)
Assessed three potential plumage ornaments of different metabolic origin
Evaluated relationship between habitat conditions and signaling system
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ImageJ software –Free from NIH
Plumage (Response variables): Crown and rump blue-green (435 – 534 nm) hue and
chroma Breast band width Tail whiteTail white
vs. Quality measures (Predictors): Age (SY vs. ASY) - ANOVA Current body condition (body mass) Condition at molt (via ptilochronology) Parental ability (feeding rate/hr/nestling)
and Habitat characteristics (basal area)
Multiple regression
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All plumage ornaments signaled age (SY vs. ASY)
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SY
ASY
Rump
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SY
ASY
Crown
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% R
efle
ctan
ce
Wavelength (nm)
BG hue and chroma; ANOVA, P < 0.001
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% R
efle
ctan
ce
Wavelength (nm)
BG chroma; ANOVA, P = 0.03
BG hue; ANOVA, P = 0.06
dth (mm)
SY ASY ANOVA; F1,53 = 11.4, P = 0.001
Log breast ban
d w
id
Age
%)
SY ASYAge
Tail white (%
ANOVA; F1,53 = 74.3, P < 0.001
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510
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(nm
)
SY ASY
R² = 0.2026
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Ru
mp
BG
hu
e (
Feeding visits/hr/nestling
Controlled for age, year F1,20 = 2.80, P = 0.008
R² = 0.3234
0.19
0.21
0.23
0.25SY ASY
0.07
0.09
0.11
0.13
0.15
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2.0 2.2 2.4 2.6 2.8 3.0 3.2
Tai
l wh
ite
(%)
Tail growth bar distance (mm)
Controlled for age, year F1,51 = 2.88, P = 0.006
No initial relationship between breast band and any quality measure, however…
Habitat contingent relationship between breast g pband width and body mass (i.e., significant interaction between body mass and basal area)
Only in moderately‐open habitats did we observe a significant relationship
The most densely populated habitat as well
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0.4
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t band w
idth (mm)
Low BA Med BA High BA
R2 = 0.23P = 0.002
R2 = 0.02P = 0.51
R2 = 0.08P = 0.09
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0.1
0.2
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8.5 9.0 9.5 10.0 10.5
Log breast
Body mass (g)
Eumelanin production regulated by melanocortin system (Roulin and Ducrest 2011)
This system of hormones is also responsible for aggressiveness, competitive ability, and stress response
Melanogenesis is genetically linked to these other traits (pleiotropy)
Elaboration of melanin plumage signals an ability to compete and respond to stress
In high‐density habitats, individuals with smaller breast bands may be challenged by conspecificmales, increasing stress and making it difficult to maintain condition
R² = 0.2275P = 0.003
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nd w
idth (mm)
SY ASY
‐0.1
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Log breast ban
BA (m2/ha)
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Support for redundant and multiple message hypotheses
All plumage ornaments signaled age (to differing extents)
Tail white signaled condition at molt (long‐term quality)
Rump chroma signaled provisioning rate (good parent hypothesis, Møller
and Thornhill 1998)
Breast band width signaled current body condition but ONLY in moderately open habitat, likely related to competitive ability of those birds (related to pleiotropic effects, Roulin and Ducrest 2011)
Birds with larger breast bands distributed non‐randomly; found more often in high‐density, moderately open forest
Dr. Lynn Siefferman (ApSU), Michael Butler and labmates (AzSU) Committee: Dr. David Buehler (UT), Dr. Pat Keyser (UT), Dr. Todd Freeberg (UT),
Dr. David Buckley (UT) Funding and support:
Field assistants: E. Boves, P. Massey, D. Raybuck, J. Piispanen, E. Pankuk, A. Langevin, D. Rankin, R. Gaillard, P. Capobianco
Andersson, M. 1994. Sexual selection. Princeton University Press, Princeton, New Jersey.
Darwin C. 1871. The descent of man and selection in relation to sex.Murray, London, UK.
Ducrest, A.‐L., L. Keller, and A. Roulin. 2008. Pleiotropy in the melanocortin system, coloration and behavioral syndromes. Trends in Ecology and Evolution 23:502–510.
Hill, G. E. and K. J. McGraw, editors. 2006. Bird coloration, vol. 2: function and evolution Harvard University Press Cambridge Massachusetts USAevolution. Harvard University Press, Cambridge, Massachusetts, USA.
Møller, A. P. and A. Pomiankowski. 1993. Why have birds got multiple sexual ornaments? Behavioral Ecology and Sociobiology 32:167–176.
Møller, A. P. and R. Thornhill. 1998. Male parental care, differential parental investment by females and sexual selection. Animal Behaviour 55:1507—1515.
Roulin, A. and A.‐L. Ducrest. 2011. Association between melanin, physiology, and behaviour: A role for the melanocortin system. European Journal of Pharmacology 660:226–233.
Searcy, W. A. and S. Nowicki. 2005. The evolution of animal communication: reliability and deception in signaling systems. Princeton University Press, Princeton, NJ, USA.
Senar, J. C. 2006. Color displays as intrasexual signals of aggression and dominance.inG. E. Hill and K. J. McGraw, editors. Bird coloration, vol. 2: function and evolution. Harvard University Press, Cambridge, Massachusetts, USA.
Wilson, A. J. and D. H. Nussey. 2010. What is individual quality? An evolutionary perspective. Trends in Ecology and Evolution 1197:1–8.
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