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1.
Carlos Navarro Tomás Pérez-Contreras Jesús M. Avilés Kevin J. McGraw Juan J. Soler 《Behavioral ecology and sociobiology》2010,64(7):1209-1067
Many colourful sexually selected signals in animals are carotenoid-dependent and, because carotenoids function as antiradicals
and immunostimulating molecules, carotenoid-dependent signals may honestly reflect the health state of individuals. Some others
nutrients like vitamin A may also enhance health and colouration, but these have rarely been tested alongside carotenoids
in colourful birds. Here, we examined whether beak colour of the spotless starling (Sturnus unicolor) reflected circulating levels of carotenoids and/or vitamin A (retinol). Spotless starlings are polygynous, sexually dimorphic
birds (i.e. length of chest feathers). The tip of the beaks of male and female spotless starlings is more intensely coloured
at the beginning of the breeding season and becomes dull after mating, which may suggest a sexual function. We found that
females have a more intensely coloured beak and higher plasma carotenoid concentration than males during mating, and, despite
the finding that carotenoid and vitamin A levels were not significantly related; colour intensity was positively correlated
with plasma concentration of carotenoids and vitamin A in both sexes. However, adult beak coloration was not associated with
carotenoid and vitamin A concentrations after nestlings were hatched. Therefore, beak colouration of spotless starlings provides
information about circulating levels of carotenoids and vitamins during the mating season and may potentially function as
a reliable signal of physiological status in the context of sexual selection. 相似文献
2.
Testosterone upregulates lipoprotein status to control sexual attractiveness in a colorful songbird 总被引:4,自引:0,他引:4
Kevin J. McGraw Stephanie M. Correa Elizabeth Adkins-Regan 《Behavioral ecology and sociobiology》2006,60(2):117-122
A salient feature of many secondary sexual characteristics in animals is that their expression is controlled by sex-steroid hormones. However, for only a few types of ornaments do we know the precise molecular mechanism by which androgens like testosterone (T) enhance trait production. We studied the red carotenoid-based beak of male zebra finches (Taeniopygia guttata), which serves as a sexually selected trait and is thought to be T dependent. In previous research, we demonstrated that the extent to which male finches produce lipoproteins in the bloodstream, which bind carotenoid pigments acquired from the diet and transport them to peripheral tissues, regulates the accumulation of carotenoids in the body and beak pigmentation. Here we show that T acts to upregulate lipoprotein production and allows male zebra finches to display flashy, sexually attractive coloration. Levels of circulating T in blood positively and significantly predicted lipoprotein profile (as measured by cholesterol levels), blood carotenoid concentration, and beak color. Exogenous T administration elevated cholesterol and carotenoid status as well as beak redness. Last, experimental inhibition of T (using the anti-androgen flutamide) downregulated lipoprotein production and carotenoid circulation and faded the beak. This androgen- and lipoprotein-mediated system represents one of the more detailed physiological mechanisms underlying the development of a sex-steroid-dependent trait in animals. 相似文献
3.
Gladbach A Gladbach DJ Kempenaers B Quillfeldt P 《Behavioral ecology and sociobiology》2010,64(11):1779-1789
Although studies on the evolution and function of female ornaments have become more numerous in the last years, the majority
of these studies were carried out in cases where female ornaments were a smaller and duller version of the ornaments found
in males. There are substantially fewer studies on species with female-specific ornaments. However, no study so far investigated
the potential of female-specific colouration as a quality signal in birds with conventional sex roles. We studied female-specific
ornamentation in a strongly sexually dichromatic species, the upland goose Chloephaga picta leucoptera, in two consecutive years. Male upland geese have white head and breast feathers and black legs, whereas females have reddish-brown
head and breast feathers and conspicuous yellow-orange legs. We found that female-specific colouration in upland geese can
reliably indicate different aspects of female phenotypic quality. Females with more orange coloured legs and more red-like
head colours had higher clutch and egg volumes than females with a paler leg and head colouration, and a more reddish plumage
colouration was related to a higher body condition. These relationships provide the theoretic possibility for males to assess
female phenotypic quality on the basis of colouration. Furthermore, the females with a more orange-like tarsus colouration
had higher plasma carotenoid levels. Both tarsus colouration and carotenoid concentrations of individual females were highly
correlated across years, indicating that tarsus colour is a stable signal. Despite this correlation, small individual differences
in plasma carotenoid concentrations between the two study years were related to differences in tarsus colouration. We thus
show for the first time in a wild bird and under natural conditions that carotenoid-based integument colouration remains consistent
between individuals in consecutive years and is also a dynamic trait reflecting individual changes in carotenoid levels. In
this species, where pairs form life-long bonds, the honesty of the carotenoid-based integument colouration suggests that it
may be a sexually selected female ornament that has evolved through male mate choice. 相似文献
4.
S. Casagrande D. Costantini G. Dell’Omo J. Tagliavini T. G. G. Groothuis 《Behavioral ecology and sociobiology》2012,66(9):1319-1331
Despite extensive research, the potential costs that keep secondary sexual traits honest and evolutionary stable remain somewhat elusive. Many carotenoid-based signals are regulated by testosterone (T), which has been suggested to impose a cost to the signaller by suppression of the immune system or an increase in oxidative stress. Results are, however, inconsistent, which may be due to the fact that T can be metabolised to both 5α-dihydrotestosterone (DHT, a potent androgen) and oestradiol (E2, a potent oestrogen). To evaluate for the first time the independent effect of these testosterone metabolites on oxidative status, circulating carotenoids and a carotenoid-dependent sexual signal, we administered DHT and E2 to captive non-breeding adult kestrels Falco tinnunculus of both sexes. E2 increased oxidative damage and downregulated the antioxidant barrier without affecting colouration or circulating carotenoids. In contrast, DHT did not affect oxidative status, but increased skin redness, again without affecting circulating carotenoids. No sex-specific effects were found. These results suggest that the pro-oxidant activity of T could be induced indirectly by its metabolite, E2, whereas the other metabolite, DHT, stimulates signal expression. Finally, the study shows that changes in oxidative damage or antioxidant status of plasma were not correlated with either skin redness or circulating carotenoids. 相似文献
5.
F. Mougeot J. Martínez-Padilla L. Pérez-Rodríguez G. R. Bortolotti 《Behavioral ecology and sociobiology》2007,61(5):741-751
Among the most familiar sexual signals are red, yellow, and orange sexual traits pigmented by carotenoids. Many birds can
detect near-ultraviolet (UV) light, and UV signals can play key roles in mate choice. Grouse (Tetraonidae) exhibit bright
carotenoid-dependent sexual ornaments, their supra-orbital combs, which to humans appear orange-red. Combs also reflect in
the UV, which is not visible to humans but is likely to be visible to grouse. In male red grouse Lagopus lagopus scoticus, we show that comb UV reflectance decreases with increasing comb size and redness. By removing the epidermis of combs, where
carotenoid pigments are, we show that the UV reflectance is a property of the dermis, underneath the red pigmented epidermis.
Carotenoid pigmentation of combs acted as a mask to reduce reflectance by the dermis in the range 400–550 nm and in the UV,
300–400 nm. Patagium skin (non-ornamental skin under the wing) also reflects in the UV, but epidermis removal on this bare
part tended to reduce UV reflectance, whereas removal of the red epidermis of combs increased UV reflectance. Males in better
condition (greater body mass relative to size) had bigger and redder combs, but with less UV. Thus, carotenoid pigments of
grouse combs are deposited on a white background with significant UV reflectance, which can influence how the signal is perceived
by conspecifics. Carotenoid-based traits exhibit UV reflectance in a number of species, but how UV reflectance and carotenoid
pigmentation influence colour remains little known for integumentary ornaments compared to plumage traits. UV vision is not
uncommon in birds and other animals, so future studies should investigate how UV reflectance influences the perception of
carotenoid-based signals of quality. 相似文献
6.
Peter D. Dijkstra Renske Hekman Rüdiger W. Schulz Ton G. G. Groothuis 《Behavioral ecology and sociobiology》2007,61(4):599-609
The nature of the costs maintaining honesty of sexual signalling in inter- and intrasexual interactions remains a contentious
issue. For carotenoid-based colour ornaments, it has been hypothesized that the honesty of the signal is enforced when carotenoid
allocation to colour expression is traded off against carotenoid availability for immunocompetence. In addition, honesty is
enforced if androgens required for colour expression are immunosuppressive. We tested whether there is a trade-off between
colour expression and immunocompetence in a lek-breeding haplochromine cichlid fish, Pundamilia nyererei, from Lake Victoria with a carotenoid-based nuptial dress. First, we showed that expression of red nuptial colouration and
social rank in a group were positively correlated. We then successfully manipulated the level of colour advertisement by socially
stimulating individually housed males with a rival male: Stimulated males developed larger areas of red nuptial colouration
and had higher levels of circulating 11-ketotestosterone (11-KT) than non-stimulated males. We subsequently tested the humoral
immune response to a novel antigen (sheep red blood cells). There was no overall significant effect of social stimulation
on antibody production, but in the stimulated males, the degree of red colouration and the antibody response were negatively
correlated. This significant interaction between colour and treatment thus shows that the negative correlation between colouration
and antibody production is dependent on the (manipulated) social environment. This study provides correlational and experimental
evidence for a trade-off between expression of a sexual trait and one component of immune function in fish. We found no evidence
for a direct effect of 11-KT on antibody production, and we discuss alternative mechanisms that could mediate the trade-off. 相似文献
7.
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
8.
Summary. Many animals use carotenoid pigments to color their integument and become
sexually attractive. These colorants can also serve physiological functions,
protecting cells and tissues from oxidative damage as well as stimulating the immune system.
Because animals often acquire several different carotenoid pigments from their diet,
there is the potential for different carotenoids to exhibit different free-radical-scavenging
or immunoenhancing activity. We experimentally tested how two common dietary
xanthophylls - lutein and zeaxanthin - may differentially affect the immune system in
male zebra finches (Taeniopygia guttata). Male
T. guttata derive their red sexual beak colorants from these two carotenoids, and
prior studies with this species have shown that lutein and zeaxanthin together boost cell-mediated
immunity. We experimentally elevated these two dietary carotenoids separately in two
groups of non-breeding zebra finches, but found that lutein-supplemented and zeaxanthin-supplemented
males mounted similar cell-mediated immune responses (to phytohaemagglutinin, or PHA).
Although zeaxanthin is a more conjugated carotenoid than lutein and has the potential
to be a more potent antioxidant, our study suggests that such a subtle structural
difference between these two biochemicals does not differentially affect immune
performance in this songbird. 相似文献
9.
It has been proposed that blue colouration in eggs has evolved as a signal of female quality that males can use to modulate
their parental investment. This hypothesis is based in the antioxidant properties of biliverdin whose costly deposition in
the eggshell is expected to signal female antioxidant capacity and egg quality. Since maternally derived androgens are costly
to produce and may adaptively affect offspring phenotype, high-quality females may benefit by signalling their androgen investment
through egg colouration. Our aim was to investigate whether egg colour variation in the spotless starling reflected the amount
of pigments on the eggshell and whether egg pigmentation was related to female and egg quality. Chromatography analyses revealed
that spotless starling eggshells contained two different pigments: biliverdin and protoporphyrin IX with no correlation between
them. Biliverdin contents correlated positively with egg colouration indicating that darker eggs with a higher peak in the
blue–green segment of the spectrum contained higher amounts of biliverdin. Eggs containing more biliverdin were laid by high-quality
females and contained higher yolk testosterone levels. However, despite the strong correlation between biliverdin and colorimetric
variables, egg colouration did not reflect accurately female and egg quality. Our results provide evidence that eggshell pigmentation
in the spotless starling is related to female and egg quality as shown by the yolk testosterone levels. However, the lack
of relation between egg colour and female condition and egg quality do not provide evidence to support the signalling function
of egg colouration. 相似文献
10.
Ana V. Leitão Anabela H. Monteiro Paulo G. Mota 《Behavioral ecology and sociobiology》2014,68(1):63-72
Avian plumage colouration is one of the most impressive displays in nature and is frequently used as sexual signal. There is now considerable evidence that females consistently prefer males with the most elaborated colour displays. Bird colour vision expands into the ultraviolet (UV) range, which prompted several studies to test the importance of UV in mate choice, revealing that females are affected by the UV light component. These studies were mostly performed on structural plumage, whereas carotenoid-based plumage was rarely considered, although it also has a typical reflection peak in the UV. Our study tested the female choice over male yellow colouration, and whether it is influenced by UV removal, in the European serin (Serinus serinus), a sexually dichromatic cardueline finch, with males showing a conspicuous carotenoid-based yellow plumage. We shows that females preferred yellower males and that male attractiveness was lost when the UV colouration was blocked, with either of the UV-blocking techniques used. The results of our study indicate that the UV component of carotenoid colouration is important in the female mate assessment in serins and highlights the importance of considering colour perception in avian mate choice. 相似文献
11.
Jesús M. Avilés Juan J. Soler Nathan S. Hart 《Behavioral ecology and sociobiology》2011,65(9):1721-1730
It has been proposed that the blue-green bird egg colourations of many avian species may constitute a sexually selected female
signal that males can use to modulate their parental investment. A fundamental untested assumption for the validation of this
hypothesis is that males can accurately assess differences in the colour of eggs. A recent review suggests that this could
be particularly problematic when egg clutches were located within a dimly lit nest cavity, due to limitations of the visual
system in low light conditions. Here, we first used a photoreceptor noise-limited model of colour discrimination ability that
accounts for visual performance under low light conditions to study whether a typical cavity-nesting passerine, the spotless
starling Sturnus unicolor, can discriminate their eggs under the ambient illumination in their nest-holes. Secondly, we tested the validity of model
predictions with behavioural data collected in two egg discrimination experiments performed in this species. Estimated egg
detectability depended entirely on model assumptions about visual limitations linked to light intensity. Starlings would not
be able to discriminate egg differences in their nests if the model was based on the assumption that light intensity limited
detectability, whereas they could potentially perceive as different many possible pairwise clutch comparisons if the model
assumption was that light intensity did not limit detectability. Results of behavioural experiments fitted the prediction
of the visual model where light intensity did not limit detectability. Our results suggest that photoreceptor noise-limited
colour models based on stimulation of single photoreceptors cannot, at present, be used to predict egg discrimination ability
in spotless starlings under low light conditions. Future studies aiming to test egg discrimination constraints in the frame
of the sexual selection hypothesis should therefore combine both modelling and behavioural experiments to determine which
are the components of the models that produce the mismatch with the behavioural conditions. 相似文献
12.
Carotenoid-based sexual ornaments are widespread, but the role of carotenoids as honest signalers in the trade-off between coloration and antioxidant protection remains controversial. It has been suggested that the function of carotenoids might not be an antioxidant per se, but that colorful carotenoids may indirectly reflect the levels of nonpigmentary antioxidants, such as melatonin or vitamin E. We experimentally fed male Iberian green lizards (Lacerta schreiberi) additional carotenoids or vitamin E alone, or a combination of carotenoids and vitamin E dissolved in soybean oil, whereas a control group only received soybean oil. We examined the effects of the dietary supplementations on characteristics of lizard sexual coloration and of the chemical profile of femoral gland secretions. Results indicated that both carotenoids and vitamin E in the diet increased the expression of some visual signals (head and chest, but not dorsum) in comparison to controls. However, different traits were differentially affected, and in many cases, the addition of vitamin E, alone or in combination with carotenoids, had a greater effect on the expression of coloration than the addition of carotenoids alone, even for carotenoid-dependent ornaments. Our results support the idea that other nonpigmentary antioxidants, such as vitamin E, are needed in addition to carotenoids to increase the expression of coloration of L. schreiberi lizards. Therefore, coloration may only indirectly reflect the levels of nonpigmentary antioxidants. In contrast, an increase in dietary nonpigmentary antioxidant vitamin E was directly reflected in the chemical signals. Because of an observed concordance between visual and chemical signals, we suggest that both may be used in different contexts albeit conveying similar messages in different sensory channels. 相似文献
13.
The hypothesis that sexual ornaments are honest signals of quality because their expression is dependent on hormones with
immune-depressive effects has received ambiguous support. The hypothesis might be correct for those signals that are carotenoid-dependent
because the required carotenoid deposition in the signal, stimulated by testosterone, might lower the carotenoid-dependent
immune defence of the organism. Two pathways underlying this androgen-dependent honest signaling have been suggested. Firstly,
androgens that are needed for ornament expression may suppress immune defence, a cost that only high-quality animals can afford.
Alternatively, immune activation may downregulate the production of androgens in low-quality individuals. Which of these alternatives
is correct, and to what extent these effects are mediated by the different metabolites of androgens, remain open questions.
To provide answers to these questions, we manipulated the levels of testosterone (T), 5α-dihydrotestosterone (DHT), and 17-β-estradiol
(E2) in diamond doves Geopelia cuneata, a species in which both sexes exhibit a carotenoid-dependent, androgen-regulated red–orange periorbital ring of bare skin.
On the first day of the experiment (day 0), we inserted steroid-releasing implants into groups of birds and on day 14, we
subjected half of the birds to an immunological challenge by immunizing them with sheep red blood cells (SRBC). In females,
but not in males, androgen but not estradiol treatments reduced antibody production to SRBC. In addition, the immunological
challenge reduced redness and size of the trait as well as androgens levels in both sexes and in all treatments. This indicates
that an immunological challenge can lower circulating T at the cost of the trait expression. These findings are in accordance
with both pathways postulated in the immunocompetence-handicap hypothesis, but do not entirely support the idea that the immunosuppressive
effect of androgens yields honest signaling since both T and DHT were not immunosuppressive in males, for which sexual signaling
is supposed to be especially important. 相似文献
14.
Impressive variation in egg colouration among birds has puzzled evolutionary biologists for a long time. The most frequently
studied selective forces moulding egg colouration—predation and brood parasitism—have either received little empirical support
or may play a role in only a minority of species. A novel hypothesis has suggested that egg colour may be significantly influenced
by sexual selection. Females may deposit a blue-green pigment biliverdin into eggshells instead of using it for themselves
as a powerful antioxidant. By this handicap, females may signal their quality to males, which are then hypothesized to increase
their paternal effort. We experimentally tested the hypothesis in the collared flycatcher (Ficedula albicollis), a species laying blue-green eggs. We cross-fostered clutches between nests to disentangle effects of female/territory quality
and egg colour on paternal effort and nestling quality. The results supported two assumptions of sexual signalling through
egg colour hypothesis: Blue pigment seems to be a limited resource for females, and female quality is positively correlated
with the intensity of the blue-green colour. However, we did not find support for the main prediction of the hypothesis, as
male parental effort parameters (feeding frequencies to nestlings and intensity of nest defence) were unrelated to egg colour.
We discuss possible reasons for the discrepancy between our results and previous correlative analyses that supported the hypothesis
that blue egg colour may be a postmating, sexually selected signal in females. 相似文献
15.
Alberto Velando Roxana Torres Irene Espinosa 《Behavioral ecology and sociobiology》2005,58(2):175-180
Sexual selection models suggest that female choice is based on male traits that indicate their genetic or environmental condition, consequently enhancing her reproductive success by direct or indirect benefits. We investigated the relationship between male foot colour and offspring condition in the blue-footed booby, a socially monogamous seabird, with conspicuous and variably condition-dependent coloured feet that are selected by females. In a cross-fostering experiment, we found that chick condition was related to the foot colour of the foster father and, to some extent, to the foot colour of the genetic father; thus overall, the fathers sexual ornamentation (genetic and foster) explained 32% of variance of chick condition. These data suggest that foot colour, a dynamic sexually selected trait, is mostly a signal of parental contribution. In species in which males provide parental care, females may choose mates with higher parental ability. Overall, our data suggest that colourful integuments are honest signals of parental ability.Communicated by J. Graves 相似文献
16.
René Beamonte-Barrientos Alberto Velando Roxana Torres 《Behavioral ecology and sociobiology》2014,68(1):115-126
Understanding the mechanisms mediating age-dependent reproductive effort in wild animals is a major challenge in evolutionary ecology. The acquisition of molecules able to deter somatic damage could potentially improve reproductive performance, especially in physiologically compromised individuals. Carotenoids are antioxidants and immunoenhancers that animals can only obtain through diet. We tested in male blue-footed boobies whether carotenoid supplementation during incubation improves condition and reproductive performance, particularly of older males. Old birds showed lower levels of peroxidative damage than middle-aged males; however, changes of males' antioxidant capacity and peroxidative damage were not affected by carotenoid supplementation irrespective of age. Experimental old males displayed more colourful feet than control old males after 13 days of first carotenoid supplementation. The effect of carotenoids on male reproductive performance was dependent upon age: young males receiving extra-carotenoids produced chicks with smaller growth rates than control young males, whereas old males receiving extra-carotenoids produced chicks with higher growth rates than control old males. Our results highlight that carotenoids influence the relationship between age and reproductive performance and suggest a positive effect of carotenoids on reproduction of old males. 相似文献
17.
Juan A. Amat Miguel A. Rendón Juan Garrido-Fernández Araceli Garrido Manuel Rendón-Martos Antonio Pérez-Gálvez 《Behavioral ecology and sociobiology》2011,65(4):665-673
It was long thought that the colour of bird feathers does not change after plumage moult. However, there is increasing evidence
that the colour of feathers may change due to abrasion, photochemical change and staining, either accidental or deliberate.
The coloration of plumage due to deliberate staining, i.e. with cosmetic purposes, may help individuals to communicate their
quality to conspecifics. The presence of carotenoids in preen oils has been previously only suggested, and here we confirm
for the first time its presence in such oils. Moreover, the carotenoids in the uropygial secretions were the same specific
pigments found in feathers. We show not only that the colour of feathers of greater flamingos Phoenicopterus roseus became more colourful due to the application of carotenoids from uropygial secretions over the plumage but also that the
feathers became more colourful with the quantity of pigments applied over them, thus providing evidence of cosmetic coloration.
Flamingos used uropygial secretions as cosmetic much more frequently during periods when they were displaying in groups than
during the rest of the year, suggesting that the primary function of cosmetic coloration is mate choice. Individuals with
more colourful plumage initiated nesting earlier. There was a correlation between plumage coloration before and after removal
of uropygial secretions from feathers’ surfaces, suggesting that the use of these pigmented secretions may function as a signal
amplifier by increasing the perceptibility of plumage colour, and hence of individual quality. As the cosmetic coloration
strengthens signal intensity by reinforcing base-plumage colour, its use may help to the understanding of selection for signal
efficacy by making interindividual differences more apparent. 相似文献
18.
Kathryn E. Arnold Stephen D. Larcombe Lotta Ducaroir Lucille Alexander 《Behavioral ecology and sociobiology》2010,64(11):1857-1866
During mate choice, individuals are predicted to assess traits that honestly signal the quality of potential partners. Locomotor
capacity may be such a trait, potentially signalling condition and ability to resist oxidative damage. In this study, we experimentally
manipulated nutritional status: Male wild-type budgerigars, imported from Australia, were provided with either an enhanced
(EQ) or reduced quality (RQ) diet varying in vitamin (particularly retinol and α-tocopherol) and mineral levels. Then, we
assessed whether this influenced locomotor capacity, i.e. escape flight performance, and sexual attractiveness in male budgerigars
Melopsittacus undulatus. Males in the EQ group showed significantly greater total antioxidant capacity and higher blood plasma concentrations of the
dietary antioxidants retinol and α-tocopherol, but not carotenoids, than the RQ group. Over 8 weeks of flight training, males
on the EQ diet showed significantly greater improvement on the most strenuous flight test than RQ males. In mate choice trials,
females preferred EQ over RQ males. EQ males that were relatively fast in escape flight trials were more strongly preferred
in the mate preference arena than their RQ competitors. Interestingly, males with high plasma carotenoid levels flew slower
and were less attractive than males with low carotenoid levels. This might indicate that carotenoids are not effective antioxidants
in birds. Overall, our results show that dietary-derived antioxidants can influence sexual attractiveness and other fitness-related
traits through multiple pathways. Locomotor capacity appears to be an honest signal of male condition in birds. 相似文献
19.
S. I. C. O. Santos L. De Neve J. T. Lumeij M. I. Förschler 《Behavioral ecology and sociobiology》2007,61(9):1499-1506
The assessment of plumage colouration has become a common procedure in many ornithological studies, especially after the discovery
of differences between avian and human visual systems, namely the avian ability to perceive ultraviolet wavelengths. There
are many techniques available for plumage colour assessment. Nevertheless, unidirectional reflectance spectrometry seems actually
to be the method of choice and is used in most studies. The active avian visual communication skills, the physical characteristics
of the plumage surface and the birds’ body shape prompted us to study plumage colouration with different angles of incidence
and observation by bidirectional reflectance spectrometry. In this study, we explore the effect of different angles of incidence
and observation, on a single plane of incidence, on the reflectance spectrometric assessment of five differently coloured
body regions of the blue fronted Amazon parrot (Amazona aestiva). Measurements were made using a AVS-USB2000 spectrometer with a DH-2000 light source and two different reflection probes
(bifurcated fibre optic probe and a specially designed fibre holder). The results of this study illustrate clear angle dependence
of colour parameters in differently coloured non-iridescent plumage regions of the blue fronted Amazon parrot. Our results
may have direct implications on the observed transmitted information of display and its associated predation risk (trade-off)
in birds, but also in other animals. Moreover, the results show that unidirectional reflectance spectrometry alone may be
a rather limited procedure to quantify and compare true colour of a complex surface such as birds’ plumage. Therefore, slight
but behavioural important characteristics of plumage pattern may remain undiscovered with this method. 相似文献
20.
Females in several sexually dimorphic species with conventional sex roles possess ornamental traits that resemble those found
in males. The evolution of such traits, however, is still poorly understood. Bluethroats (Luscinia s. svecica) are socially monogamous, sexually dichromatic passerine birds, in which female throat patch coloration varies from near
absence to near full expression of male-like coloration. A recent study, demonstrating that male bluethroats prefer colourful
females, suggests that female coloration is subject to sexual selection through male choice. However, the benefits males may
gain from mating with colourful females have not yet been identified. In this study we tested the hypothesis that female coloration
signals parental quality (the good-parent hypothesis). During the course of the same day, we recorded female care both in
the presence and the absence of the male mate. The latter was done to eliminate the confounding effect of variable male care
by removing the male temporarily. Female coloration did not correlate with female feeding rates either in the presence or
in the absence of the male. Female feeding rates in the absence and the presence of the male were positively, although weakly,
correlated. Female coloration did not correlate with female ability to compensate for the loss of male care, or with the change
in brood mass during male removal. Therefore, there is no evidence for the good-parent hypothesis to explain female plumage
coloration in bluethroats.
Received: 4 March 1999 / Received in revised form: 14 October 1999 / Accepted: 23 October 1999 相似文献