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Lorenzo Pérez-Rodríguez 《Behavioral ecology and sociobiology》2008,62(6):995-1005
Carotenoid-based ornaments act as signals of quality in many animal species. In contrast to feathers, which are relatively
stable structures, carotenoid-pigmented integuments (e.g. bills, lores, tarsi) can change colour rapidly and may better reflect
changes in physiological condition. I studied the seasonal variations in plasma carotenoids in red-legged partridges (Alectoris rufa) kept on a constant diet and free of intestinal parasites. Furthermore, I analyzed whether seasonal changes in circulating
carotenoids were mirrored by the carotenoid-based coloration of eye rings and bill of this species. Plasma carotenoids showed
seasonal variation, with higher levels coinciding with the end of the mating and the start of the laying season. Eye ring
pigmentation was related to plasma carotenoid levels, and changes in bill hue (but not changes in UV or red bill chroma) mirrored
the variation in plasma carotenoids during the breeding season. Despite the seasonal variation, individual differences in
eye ring pigmentation and bill hue, UV and red chroma were consistent throughout the breeding season. Similarly, individual
differences in eye ring pigmentation and bill hue and red chroma remained consistent between consecutive years. These results
suggest that carotenoid based integumentary colorations act as dynamic traits that accurately reflect the carotenoid-status
of individuals, thus reliably indicating consistent differences in individual quality. Furthermore, variability in signal
expression appears to have a relevant genetic/phenotypic basis independently of environmental conditions.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
2.
Due to their high phenotypic plasticity, the expression of secondary sexual characteristics is particularly sensitive to stress.
Here, we investigated the expression of two conspicuous visual signals in great tits (Parus major) in a metal pollution gradient. In three study sites with marked differences in metal contamination (mainly lead, cadmium,
copper and zinc), we compared melanin and carotenoid colouration of great tits. While carotenoid colouration (yellow breast)
was negatively related to metal pollution, the size of a melanin trait (breast stripe) was larger in the most polluted sites.
Environmental pollutants not only affect the expression of conspicuous signals but may even enhance, directly or indirectly,
a signal of male quality such as breast stripe. Our results also support the multiple messages hypothesis predicting that
different signals highlight different aspects of geno- and phenotypic condition of the bearer. 相似文献
3.
Alexander L. Bezzerides Kevin J. McGraw Robert S. Parker Jad Husseini 《Behavioral ecology and sociobiology》2007,61(9):1401-1408
Carotenoid- and melanin-based colors are valuable indicators of quality in many vertebrates, but their signaling role in invertebrates
remains relatively unexplored. The Asian ladybird beetle Harmonia axyridis is an ideal organism for studies of this nature because males and females exhibit highly variable red and black colors on
their elytra and are chemically defended with an alkaloid (harmonine). We used digital photography to quantify elytra coloration
and absorbance spectrophotometry and gas chromatography mass spectrometry analyses to quantify pigment and alkaloid concentrations,
respectively, in wild-caught male and female H. axyridis. We predicted that extensive or intense coloration would be an aposematic signal of high-alkaloid stores. We found that carotenoid
pigments largely controlled variation in red elytra coloration. There was no relationship between alkaloid content and either
elytra redness or carotenoid pigment concentration in either sex. However, we found a positive correlation between the extent
of elytra coloration and alkaloid content. Animals with proportionally more red (or less black) on the elytra were more alkaloid-rich;
this relationship was particularly strong in females. We also found that females with lighter black spots had greater amounts
of harmonine than those with darker spots. These results suggest that elytra color patterns have the potential to reveal information
about chemical defensiveness to mates or predators. Prior studies in this species show that nonmelanic forms are typically
less active and yet more sexually attractive than melanic forms, and both results may be explained by the fact that nonmelanics
are better chemically defended. 相似文献
4.
Carotenoid-dependent coloration of male American kestrels predicts ability to reduce parasitic infections 总被引:3,自引:1,他引:2
The signaling function of sexually selected traits, such as carotenoid-dependent avian plumage coloration, has received a great deal of recent attention especially with respect to parasitism and immunocompetence. We argue that parasite-mediated models of sexual selection may have an implicit temporal component that many researchers have ignored. For example, previous studies have demonstrated that carotenoid-dependent traits can signal past parasite exposure, current levels of parasitism, or the ability of individuals to manage parasitic infections in the future. We examined repeated measures of carotenoid-dependent skin color and blood parasitism in American kestrels (Falco sparverius) to distinguish whether coloration might signal current parasitism or the potential to deal with infections in the future. We found no evidence that coloration was related to current levels of parasitism in either sex. However, coloration of males significantly predicted their response to parasitism; males with bright orange coloration during prelaying, when mate choice is occurring, were more likely than dull yellow males to reduce their levels of infection by the time incubation began. Coloration during prelaying may advertise a male’s health later in the breeding season. For kestrels, the ability to predict future health would be highly beneficial given the male’s role in providing food to his mate and offspring. Coloration of females was not a significant predictor of parasitism in the future, and we provide several possible explanations for this result. 相似文献
5.
Models of parasite-mediated sexual selection propose that males with more elaborate sexual traits will have fewer parasites. These models have generally been tested using metazoan or protozoan parasites of the blood, gut, or integument. Fewer studies have examined sexual ornaments in relation to bacterial infections. While most surface bacteria are harmless or beneficial, feather-degrading bacteria may have detrimental effects. In this study, we examined the relationships between overall bacterial load, feather-degrading bacterial load, and sexually selected carotenoid-based plumage color in a wild population of house finches (Carpodacus mexicanus). We found that males with the redder plumage preferred by females had similar overall bacterial loads, but lower feather-degrading bacterial loads, than males with less red plumage. These data suggest that plumage color can signal abundance of feather-degrading bacteria to potential mates. It remains unclear whether feather-degrading bacteria directly or indirectly affect plumage color, but the observed correlations suggest that feather-degrading bacteria may play some role in sexual selection. 相似文献
6.
Limitations to colour-based sexual preferences in three-spined sticklebacks (Gasterosteus aculeatus) 总被引:2,自引:0,他引:2
Female three-spined sticklebacks (Gasterosteus aculeatus) are suggested to select mates based on their red nuptial coloration, males with a redder display being more preferred. Although
there are both laboratory and field data to support this view, there are also published accounts where females do not show
a preference for the redder male. Here we report the results of a series of 19 trials where receptive gravid female three-spined
sticklebacks were allowed to choose between two size-matched rival males. We used photographic and image analysis techniques
to quantify male nuptial coloration to investigate how the magnitude of the colour difference between the two alternative
males influenced female preferences. Using the amount of time a female spent oriented towards each male as a measure of his
attractiveness to her, females were not always found to select the redder of the two presented males. We did, however, find
that that the relative difference in coloration of the two males in each pair was important in determining the level of coloration-based
preference, with females only selecting redder males consistently when the difference in coloration was sufficiently large.
Received: 26 October 1999 / Received in revised form: 10 January 2000 / Accepted: 13 February 2000 相似文献
7.
Allocation trade-offs of carotenoids between their use in the immune system and production of sexual ornaments have been suggested
as a proximate mechanism maintaining honesty of sexual signals. To test this idea, we experimentally examined whether carotenoid
availability in the diet was related to variation in antibody response to novel antigens in male greenfinches (Carduelis chloris aurantiiventris), a species with extensive carotenoid-dependent plumage colouration. We also measured the cost of mounting a humoral response
in terms of circulating carotenoids. Finally, we examined the relationship between plumage colour, immune response and circulating
carotenoids. We found that males with carotenoid-supplemented diets showed stronger antibody response than non-supplemented
birds. We also found that activation of the immune system significantly reduced circulating carotenoids (24.9% lower in immune-challenged
birds than in control birds). Finally, intensity (chroma) of ventral plumage colouration of males, a character directly related
to concentration of total carotenoids in feathers, was negatively correlated with the immune response and circulating carotenoids
in winter. These results support the idea that carotenoids are a limiting resource and that males trade ornamental colouration
against immune response. 相似文献
8.
Patrick Gautier Marco Barroca Sophie Bertrand Cyril Eraud Maria Gaillard Michael Hamman Sébastien Motreuil Gabriele Sorci Bruno Faivre 《Behavioral ecology and sociobiology》2008,62(7):1159-1166
Several environmental factors have been shown to shape the pattern of investment of carotenoids into the expression of sexual
signals. Surprisingly, the impact of the social environment has been neglected. If a carotenoid-based sexual trait is used
by females to choose a mate or by males to assess the quality of potential competitors for mates, males, in the presence of
females, should upregulate expression of the trait. We tested this hypothesis in male zebra finches that were housed either
with females or in a male-only social environment. Additionally, to investigate whether the social modulation of the expression
of a sexual trait depends on the physiological need of carotenoids, we challenged half of the males with Escherichia coli lipopolysaccharide (LPS). We found that the social environment modulated the expression of bill color, with males kept in
the presence of females harboring a redder bill at the end of the 3 weeks that the experiment lasted. Males injected with
LPS showed duller bill color regardless of the presence of females, and social interactions with females result in upregulated
bill color similarly for phosphate-buffered saline (PBS) and LPS males. Thus, social environment and immune activation had
an additive effect on the expression of bill color. The effect of social environment on plasma carotenoids was less clear.
Indeed, a first replicate of the entire experiment showed that both immune challenge and social context affected bill color,
with a negative effect of immune challenge and a positive effect of the presence of females on circulating carotenoids. However,
a second replicate of the experiment showed only a negative effect of the immune challenge. These results, therefore, suggest
that the social environment can affect the expression of carotenoid-based sexual traits under both benign and carotenoid-demanding
conditions. Whatever the signaling function of bill color (female mate choice or male–male competition for mates), the observed
flexibility may be adaptive because the expression of the signal can be modulated depending on the expected rewards or costs
associated with the presence or absence of females. Nevertheless, the mechanisms underlying such an effect are still unknown. 相似文献
9.
Carotenoid pigments cannot be synthesized by vertebrates but must be ingested through the diet. As they seem to be a limited
resource, carotenoid-based ornaments are particularly interesting as possible honest signals of individual quality, in particular
of foraging efficiency and nutritional status. Some studies have demonstrated the condition dependence of carotenoid-based
plumage in birds. However, many other carotenoid-pigmented bare parts (i.e. skin, caruncles, bills, cere, and tarsi) are present
in birds but, in comparison with plumage, little is known about these traits as indicators of individual quality. Here, we
show that the eye ring pigmentation and bill redness of the red-legged partridge (Alectoris rufa) are positively associated to body condition and recent changes in body mass. Also, we found a negative relationship between
these two traits and heterophil-to-lymphocyte ratio, an indicator of physiological stress (the relationship with bill redness
being significant only for males). In an experiment, we found that after a period of reduction in food intake (with the consequent
loss of body mass), food-restricted birds showed lower eye ring pigmentation than ad-libitum-fed birds. Therefore, different
ornaments seem to reflect changes in body condition but at different speeds or intensities (eye ring, a fleshy ornament, appears
to respond more rapidly to changes in the nutritional status than a keratinized structure as the bill). These results indicate
that carotenoid-based ornaments are condition-dependent traits in the red-legged partridge, being therefore susceptible to
be employed as honest signals of quality in sexual selection. 相似文献
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