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11.
Ultraviolet (UV) reflectance of the plumage is common in birds and plays an important role in sexual signalling. Recently,
it has been proposed that birds are able to modify plumage UV reflectance by the application of uropygial gland secretion.
Based on a survey of the optical properties of this secretion from 51 species belonging to 12 avian orders, we show that two
main types of uropygial secretions exist, one predominantly found in passerines and one in non-passerines, both reducing relative
UV reflectance of a white background (Teflon™ tape). We quantified how each type of secretion (exemplified by blue tit and
mallard) affected feather UV reflectance. Both secretions reduced overall brightness and relative UV reflectance of white
mallard feathers but hardly affected the reflectance of UV/blue blue tit crown feathers. According to models of avian colour
vision, changes in reflectance due to application of the secretion were at or below the discrimination threshold of most birds.
We conclude that the uropygial secretion is unlikely to play a major role in modifying plumage UV reflectance. However, the
optical properties of the uropygial secretion may have been selected to interfere as little as possible with visual signaling
through plumage reflectance.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
Rosemary?StrasserEmail author Hubert?Schwabl 《Behavioral ecology and sociobiology》2004,56(5):491-497
Vertebrate eggs contain maternal steroid hormones in their yolks; and in avian species the concentration of these steroids vary within and among clutches. The organizational actions of these variable doses of maternal steroids in the avian egg, analogous to those regulating the development of sexually dimorphic traits, are little explored. In this study, we examined the organizational effects of yolk testosterone in the house sparrow,
Passer domesticus, a sexually dichromatic passerine bird in which males are characterized by the presence of a throat patch or badge of black feathers that varies in size among males. We injected a physiological dose of testosterone or vehicle into eggs in the field, removed nestlings, and hand-raised them in the laboratory. At 5 months of age, we investigated treatment effects on plumage and behavior. Males that hatched from testosterone-injected eggs developed a larger badge than males that hatched from vehicle-injected (control) eggs. However, testosterone did not induce the expression of a badge in females. In staged dyadic encounters, both males and females hatched from testosterone-injected eggs were more successful at obtaining and defending a food source than individuals of the same sex hatched from control eggs. The results suggest that variable concentrations of maternal testosterone in the eggs of the house sparrow organize the expression of a plumage trait in males and behavior in both sexes.Communicated by J. Graves 相似文献
13.
A. Peters K. Delhey W. Goymann B. Kempenaers 《Behavioral ecology and sociobiology》2006,59(5):666-673
The proximate basis of sexual traits can suggest mechanisms maintaining honesty in signalling. A central role hereby has been
attributed to testosterone, although its importance for brightly coloured plumage has been questioned. We determined circulating
testosterone levels in male blue tits captured at the start of breeding and demonstrated an age-dependent relationship between
testosterone and male crown UV/blue coloration. In yearling males, testosterone increases with increasing ornamentation (higher
UV chroma, higher chroma, more UV-shifted hue), whereas in older males, this relationship is negative, with less UV-ornamented
males having higher testosterone. This pattern is robust since it occurred in 2 years, before and after egg laying, and in
males sampled during the day and during the night, despite a tenfold difference in testosterone levels. Since more UV-ornamented
young males gain higher within-pair paternity, while less UV-ornamented older males achieve more extra-pair matings, the results
imply that higher testosterone is associated with reproductive success and attractiveness in both age classes. We hypothesise
that this relationship could result from causal effects of testosterone on coloration or through associations with behaviour
and suggest ways to test these hypotheses. Our results caution against premature dismissal of a potential role for testosterone
in maintaining honesty of plumage signals. 相似文献
14.
Osmo Rätti Matti Hovi Arne Lundberg Håkan Tegelström Rauno V Alatalo 《Behavioral ecology and sociobiology》1995,37(6):419-425
The pied flycatcher (Ficedula hypoleuca) is sexually dichromatic with extreme variation in male plumage coloration. The benefit for males of having black plumage is controversial, and few studies have found evidence for a sexual selection benefit of being black rather than brown. However, blacker males may be better able to achieve extra-pair fertilizations (EPFs), which may be an important component of sexual selection. We studied the role of EPFs in sexual selection in the pied flycatcher by establishing a set-up where two males with different back coloration (blacker vs browner) bred simultaneously near each other. DNA fingerprinting analysis revealed that 11% of offspring resulted from EPFs, and that 22% of broods included extra-pair young (EPY) among 36 nests containing 223 nestlings. We found no evidence that browner males suffered more often from EPFs than blacker males. There was no correlation of male or female morphology or age with EPF frequency. However, breeding pairs with low genetic similarity had EPY in their nests significantly more often. Thus we argue that females paired with genetically dissimilar males may try to avoid the effects of extreme outbreeding by seeking extra-pair copulations (EPCs). Alternatively, incompatibility between genetically dissimilar mates may simply expose females to more extra-pair copulations. 相似文献
15.
Delayed plumage maturation in Lazuli buntings: tests of the female mimicry and status signalling hypotheses 总被引:1,自引:0,他引:1
Vincent R. Muehter Erick Greene Laurene Ratcliffe 《Behavioral ecology and sociobiology》1997,41(4):281-290
The evolutionary importance of delayed plumage maturation (DPM) in passerines, the condition when more than 1 year is required
to achieve adult-like coloration, remains highly contentious. Adaptive hypotheses propose that aggression from after 2nd-year
(ASY) males or predation favors DPM in 2nd-year (SY) males, thereby increasing SY male survivorship or reproductive success.
However, each hypothesis suggests a distinct selective mechanism explaining “how” this is accomplished. Alternatively, DPM
may be a consequence of a nonadaptive molt constraint. We tested the female mimicry and status signalling hypotheses in territorial
ASY male lazuli buntings (Passerinaamoena) using three sets of model presentation experiments. The female mimicry hypothesis proposes that dull SY male plumage deceptively
mimics female plumage, and predicts that ASY males can not distinguish SY male from female plumage. The status signalling
hypothesis proposes that dull SY male plumage honestly signals low competitive threat, and predicts that ASY males respond
less aggressively to dull versus bright, ASY-like plumage. Contrary to the female mimicry hypothesis, ASY males distinguished
between SY male and female plumage, as they were aggressive to SY male models exclusively and attempted to copulate with female
models. Supporting the status signalling hypothesis, ASY males were significantly less aggressive to SY versus ASY male plumage.
While DPM may result from a physiological constraint on bright SY male plumage, our results support the idea that dull plumage
in an SY male's first breeding season may be maintained by selection to reduce aggression from ASY males, serving as a signal
of competitive status.
Received: 21 February 1997 / Accepted after revision: 16 June 1997 相似文献
16.
Ismael Galván 《Behavioral ecology and sociobiology》2008,63(2):303-311
Animal ritualized displays have been classically viewed as behavioral characters that decrease signal ambiguity or that facilitate
the evaluation of costly exhibitions. It has been shown that their prevalence and level of complexity across species can reflect
phylogenetic relationships between them, but the adaptive function of these behavioral traits is poorly known. Here, I hypothesize
that, given that the efficacy of visual displays basically depends on conspicuousness and level of performance, species with
low levels of conspicuousness may be forced to perform more complex varieties of a given display to get the same signal efficiency
than other more conspicuous species. Thus, the evolution of display complexity, considered as the level of exaggeration of
ritualized movements, may be explained as an adaptive trait and not only by phylogenetic inertia. I illustrate and test this
hypothesis with the case of black-and-white plumage patches of pelecaniform birds. As predicted, there was a negative correlation
between level of complexity and species conspicuousness (proportion of unmelanized plumage) for two different social displays.
This indicates that classical ideas on the adaptiveness of ritualized displays should be considered to understand the present
variation in signal form across species, which sheds light on the evolution of multiple signals. 相似文献
17.
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
18.
Status signals are traits that advertise an individual’s competitive abilities to conspecifics during aggressive disputes.
Most studies of status signals in birds have focussed on melanin-based plumage signals, but recent research shows that carotenoid-based
signals may also play a role in aggressive signaling. We assessed the relative importance of melanin- and carotenoid-based
plumage patches as agonistic signals in a small passerine, the golden whistler (Pachycephala pectoralis). Display signals in male golden whistlers include an unpigmented white throat patch, a carotenoid-based yellow breast and
nape band, and a melanin-based black chin-stripe. We found that only the white throat patch was correlated with contest-related
attributes. Males possessing large throat patches defended larger territories and commenced breeding earlier. When caged males
with either experimentally reduced, or unmanipulated throat patches were presented to conspecifics, those with experimentally
reduced patches attracted less aggression from male subjects. Focal males also responded faster to caged males with throat
patches similar in size to their own, suggesting that they may assess relative throat patch size before engaging in aggressive
encounters. Females did not discriminate between “reduced” or “control” treatments. Our data strongly suggest that only the
unpigmented throat patch functions as a status signal. As this signal is unlikely to have significant development costs, honesty
may be maintained through social costs. 相似文献
19.
Several experimental studies have shown that female birds use ornamental melanin and carotenoid plumage coloration as criteria
in mate choice. Whether females choose mates based on natural variation in structural coloration, however, has not been well
established. Male eastern bluebirds (Sialia sialis) display brilliant ultraviolet (UV)-blue plumage coloration on their head, back, wings, and tail, which is positively correlated
with condition, reproductive effort, and reproductive success. We experimentally tested the hypothesis that female eastern
bluebirds prefer as mates males that display brighter structural coloration by presenting breeding-condition females with
males of variable coloration. We conducted two types of mate-choice experiments. First, females chose between males whose
coloration was manipulated within the natural range of variation in the population; feathers were either brightened with violet
marker or dulled with black marker. Second, females chose between males with naturally dull or bright plumage coloration.
In both manipulated and unmanipulated coloration trials, female choice did not differ significantly from random with respect
to structural coloration. We found no support for the hypothesis that the UV–blue coloration of male eastern bluebirds functions
as a criterion in female mate choice. 相似文献
20.
Ioana Chiver Bridget J. M. Stutchbury Eugene S. Morton 《Behavioral ecology and sociobiology》2008,62(12):1981-1990
Extra-pair fertilizations are common in many socially monogamous species, and paternity studies have indicated that females
may use male vocal performance and plumage ornaments as cues to assess male quality. Female off-territory forays may represent
a key component of female choice and male extra-pair mating success, and female foray behaviour is expected to be strongly
influenced by indictors of male quality. In this study, we examined how male song and ornamentation affect how often females
left their territories, which males they visited and extra-pair paternity in a socially monogamous passerine, the hooded warbler
(Wilsonia citrina). We radiotracked 17 females during the fertile period and quantified male vocal performance (song output and rate) and plumage
characteristics (size of the black melanin hood and colour of the black hood, yellow cheeks and breast areas). We obtained
blood samples and determined paternity at 35 nests including those of 14 females that we radiotracked. Eleven (65%) of the
17 females forayed off-territory, whilst fertile and female foray rate was positively correlated with the number of extra-pair
young in the nest. Females that left their territories more frequently were paired with males that sang at a low rate. In
addition, extra-pair mates had higher song rates than the social mates they cuckolded (5.3 songs/min vs. 4.4 songs/min). Female
off-territory forays or extra-pair paternity were not significantly related to male plumage characteristics. Our results indicate
that a high song rate influences both the foray behaviour of a male’s social mate and the likelihood that he will sire extra-pair
offspring with neighbouring females. 相似文献