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A structural colour ornament correlates positively with parasite load and body condition in an insular lizard species

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Pigment-based ornaments in vertebrates may reflect the body condition or health status of the individual in correlation with environmental stress and hormonal balance. Among the environmental factors shaping sexual colouration, parasitic infections have been stressed as an important evolutionary pressure constraining the maintenance of pigment-based ornaments. However, the honesty of structure-based ornaments in vertebrates is still under debate. Structural UV-biased ornaments in Gallotia lizards were described as a trait used by conspecifics during mate and rival assessment suggesting the reliability of these signals. We investigated the relationship between parasitaemia, body condition and a structural-based ornament present in the cheek of the sexually dichromatic Canarian lacertid Gallotia galloti in a population with an almost 100 % prevalence of haemoparasites. Using spectrophotometric techniques, we found that males with higher values of cheek UV chroma were infected with more haemoparasites. No significant relationship was found between haemoparasite load and body condition. However, males with higher cheek UV chroma showed significantly better body condition. In addition, we found that cheek hue was significantly related to body condition of individuals in both sexes. In males, cheek reflectivity biased towards the UV range was significantly related to better body condition. In females, those individuals with better body condition showed more whitish cheeks with less UV suggesting that cheek hue serves as an intersexual signal for sex recognition. We conclude that the positive relationship between cheek chroma and parasite load in male lizards is compatible with both differential density of melanin and iridophore arrangement in the dermis conveying an individual’s ability to cope with environmental stress.
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ORIGINAL PAPER
A structural colour ornament correlates positively with parasite
load and body condition in an insular lizard species
Rodrigo Megía-Palma
1
&Javier Martínez
2
&Santiago Merino
1
Received: 28 November 2015 /Revised: 22 May 2016 /Accepted: 26 May 2016/Published online: 4 June 2016
#Springer-Verlag Berlin Heidelberg 2016
Abstract Pigment-based ornaments in vertebrates may re-
flect the body condition or health status of the individual in
correlation with environmental stress and hormonal balance.
Among the environmental factors shaping sexual colouration,
parasitic infections have been stressed as an important evolu-
tionary pressure constraining the maintenance of pigment-
based ornaments. However, the honesty of structure-based
ornaments in vertebrates is still under debate. Structural UV-
biased ornaments in Gallotia lizards were described as a trait
used by conspecifics during mate and rival assessment sug-
gesting the reliability of these signals. We investigated the
relationship between parasitaemia, body condition and a
structural-based ornament present in the cheek of the sexually
dichromatic Canarian lacertid Gallotia galloti in a population
with an almost 100 % prevalence of haemoparasites. Using
spectrophotometric techniques, we found that males with
higher values of cheek UV chroma were infected with more
haemoparasites. No significant relationship was found be-
tween haemoparasite load and body condition. However,
males with higher cheek UV chroma showed significantly
better body condition. In addition, we found that cheek hue
was significantly related to body condition of individuals in
both sexes. In males, cheek reflectivity biased towards the UV
range was significantly related to better body condition. In
females, those individuals with better body condition showed
more whitish cheeks with less UV suggesting that cheek hue
serves as an intersexual signal for sex recognition. We con-
clude that the positive relationship between cheek chroma and
parasite load in male lizards is compatible with both differen-
tial density of melanin and iridophore arrangement in the der-
mis conveying an individuals ability to cope with environ-
mental stress.
Keywords Colour .Gallotia .Hamilton and Zuk hypothesis .
Handicap Principle .Island ecology .Parasite .Sexual
selection
Introduction
The Handicap Principle (Zahavi 1975) proposed a theoretical
framework to explain the persistence of conspicuous orna-
ments in nature. Individuals are tested by the handicap that
implies bearing a conspicuous, or even exaggerated, trait or
behaviour (Zahavi 1975). An exaggeration of these characters
without a correlation to an adaptive advantage should lose its
effect by negative selection (Zahavi 1975;Grafen1990). In
several vertebrates including lizards, colour ornaments have
been studied as signals of individual quality used by conspe-
cifics during rival or mate assessment (Cooper and Burns
1987; Stapley and Whiting 2006; Martín and López 2009;
Bajer et al. 2010,2011). Parasites exert a selective environ-
mental pressure shaping sexual ornaments (Hamilton and Zuk
1982;ResselandSchall1989;Calisietal.2008;Molnáretal.
2013). The hypothesis formulated by Hamilton and Zuk
(1982) assumes that: (1) females choose mates on the basis
of secondary sex characters, (2) the full expression of these
characters is limited by parasite infection, (3) females choose
males with exaggerated secondary traits to obtain resistance
Communicated by: Sven Thatje
*Rodrigo Megía-Palma
rodrigo.megia@mncn.csic.es
1
Departamento de Ecología Evolutiva, Museo Nacional de Ciencias
Naturales-CSIC, J. Gutiérrez Abascal 2, E-28006 Madrid, Spain
2
Área Parasitología. Departamento de Biomedicina y
Biotecnología.Facultad de Farmacia, Universidad de Alcalá de
Henares, Alcalá de Henares, E-28871 Madrid, Spain
Sci Nat (2016) 103: 52
DOI 10.1007/s00114-016-1378-8
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
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