共查询到20条相似文献,搜索用时 515 毫秒
1.
Rebecca J. Safran Kevin M. Pilz Kevin J. McGraw Stephanie M. Correa Hubert Schwabl 《Behavioral ecology and sociobiology》2008,62(3):427-438
Recently, evidence is mounting that females can adaptively engineer the quality of their offspring via the deposition of yolk
compounds, including carotenoids and androgens. In this study, we simultaneously consider how both carotenoids and androgens
in egg yolk relate to parental quality in barn swallows (Hirundo rustica erythrogaster). First, we found no relationship between concentrations or amounts of yolk androgens and carotenoids. Yolk carotenoids decreased
with laying order, whereas we found no relationship between yolk androgens and laying order. Second, we tested the Investment
Hypothesis, which predicts that high-quality females or females paired to high quality mates, allocate differentially more
of these yolk compounds to their offspring. For carotenoids, we mostly found evidence to counter predictions of the Investment
hypothesis: (1) Carotenoid concentrations varied among females, (2) heavier eggs contained lower carotenoid concentrations,
although heavier yolks contained greater amounts of carotenoids, (3) eggs of earlier-laying females had lower concentrations
in their eggs, and (4) yolk carotenoids were not correlated with clutch size or male plumage ornamentation. For androgens,
we found weak support for the Investment Hypothesis: (1) Yolk androgens varied among females, (2) heavier eggs and yolks contained
greater amounts, although not concentrations of androgens, (3) females paired to more colorful males laid eggs with greater
concentrations of androgens, and (4) no effects of laying date or morphological correlates of female quality on androgen concentrations
in egg yolks. Overall, these findings suggest that each yolk compound may have different functions and therefore may be regulated
by different mechanisms. 相似文献
2.
János Török Rita Hargitai Gergely Hegyi Zoltán Matus Gábor Michl Péter Péczely Balázs Rosivall Gyula Tóth 《Behavioral ecology and sociobiology》2007,61(4):541-550
Birds may influence the fitness of their offspring by transmission of different amounts of carotenoids to their eggs. Carotenoids
play crucial roles in antioxidant protection and immune defence mechanisms, but they may be available to females in limiting
amounts. Therefore, their allocation to the eggs may be influenced by the female’s condition, age and environmental circumstances.
Furthermore, the quality of the male parent, which affects the reproductive value of the offspring, may also influence this
investment. In this correlational study, we investigated proximate and ultimate factors that may lead to variation in yolk
lutein, zeaxanthin and β-carotene concentrations among and within clutches of a wild passerine, the collared flycatcher (Ficedula albicollis). We found that carotenoid concentration was positively associated with caterpillar supply at the time of egg formation,
which suggests a proximate constraint of carotenoid availability on yolk composition. Neither female condition, body size,
age, nor male plumage ornamentation, age and body size correlated with carotenoid deposition. Yolk β-carotene concentration
was found to be positively linked to yolk testosterone concentration. We suggest that females allocated more β-carotene to
their eggs to mitigate the potentially detrimental effects of elevated steroid concentration. We found that concentration
of β-carotene increased with laying order. The possible function of this pattern may be to enhance the resistance to oxidative
stress and pathogens of the disadvantaged last-hatching nestling, suggesting that collared flycatchers pursue a compensatory,
“brood survival” strategy. 相似文献
3.
Suvi Ruuskanen Blandine Doligez Lars Gustafsson Toni Laaksonen 《Behavioral ecology and sociobiology》2012,66(9):1201-1211
Early growth conditions, such as exposure to maternally derived androgens in bird eggs, have been shown to shape offspring in ways that may have important long-term consequences for phenotype and behavior. Using an experimental approach, we studied the long-term effects of yolk androgens on several phenotypic traits and parental behavior in adult and female collared flycatchers (Ficedula albicollis). We elevated yolk androgen levels and monitored the experimental recruits the following breeding seasons. Androgen treatment had a sex-dependent effect on adult body condition, yolk androgen-treated males being heavier than control males when controlling for size, a result which may be caused potentially by selective mortality, physiological differences, or different life-history strategies. Androgen treatment did not however affect the expression of sexually selected plumage ornaments (forehead and wing patch size), UV coloration, or parental feeding rate in either sex. Our results suggest that yolk androgens are unlikely to affect sexual selection via plumage characteristics or contribute to breeding success via altered parental care. Yolk androgens do not seem to act as a means for female collared flycatchers to enhance the attractiveness of their sons. The lower return rate previously observed for androgen-treated male offspring compared to controls may therefore not be due to lower mating or breeding success, but may rather reflect lower survival or higher dispersal propensity of yolk androgen-treated males. 相似文献
4.
Caroline Isaksson Tobias Uller Staffan Andersson 《Behavioral ecology and sociobiology》2006,60(4):556-562
Carotenoid pigments have attracted much interest in behavioural and evolutionary ecology because of their dual function in immune physiology and as color signals. In vertebrates, carotenoids must ultimately be obtained from the diet, and the mechanisms and magnitude of this environmental dependence are central for understanding carotenoid signal functions and evolution. In the present cross-fostering experiment with great tits Parus major, we investigate pre- and postnatal parental effects (egg yolk carotenoids, parental coloration) on nestling size and carotenoid coloration, using HPLC analysis of egg yolk carotenoids, and a reflectance-based measure of ‘chroma’ that reflects the plumage pigment concentration. Both rearing environment and origin influenced offspring size and plumage chroma. Maternal allocation of carotenoids to eggs had a weak positive effect on nestling plumage chroma, whereas we found no prenatal maternal effects (egg size or yolk carotenoid concentration) on size. Nestling plumage chroma was also significantly predicted by the chroma of the rearing father, but not by the color of the rearing mother or either of the original (genetical) parents. Thus, both prenatal maternal effects and postnatal paternal effects influence the carotenoid-based plumage coloration of nestling great tits. Future studies will reveal if parental effects have long-term consequences for plumage development and associated fitness components. 相似文献
5.
The theory of sex allocation suggests that if the reproductive value and the cost of producing/rearing offspring differ between
male and female offspring, parents should invest differently in sexes depending on environmental conditions. Female parents
could allocate more resources to eggs of one sex to compensate potential sex-dependent constraints later during the nestling
period. In this study, we tested the influence of environmental conditions on sexual dimorphism in eggs of Eurasian kestrels
(Falco tinnunculus) by experimentally manipulating food availability before laying. We found that an increase in food abundance before laying
did not increase egg mass but changed sex-dependent resource distribution in eggs. In food-supplemented pairs, but not in
control pairs, egg mass and hatchling mass were similar between males and females. In addition, we found, in the food-supplemented
group, that the latest hatched females showed shorter hatching times than in the control group. In control pairs, female eggs,
hatchlings and nestlings were heavier than males. In addition, male fledglings in the food-supplemented group gained less
mass than those in the control group. As that food abundance was only increased until the onset of laying, female kestrels
were expected to invest in eggs taking food abundance before egg formation as a predictor of future conditions during brood
rearing. Our study shows that environmental conditions before laying promote a subtle adjustment of the resources invested
in both sexes of offspring rather than in other breeding parameters. This adjustment resulted in a shortening of hatching
time of the last hatched females that possibly gives them advantages in their competitive capacity with respect to male nest-mates. 相似文献
6.
Carotenoid-based ornaments (many yellow–orange–red colourations) may signal the genetic or parental quality of the bearer. Thus, their expression could influence the amount of resources/energy that the mate will invest in the production of offspring, thereby optimising its reproductive fitness. The differential allocation hypothesis (DAH) predicts that females mated with more attractive males should lay more and better eggs. This has been explored only in few bird species with carotenoid-based traits. We tested this hypothesis in the red-legged partridge (Alectoris rufa), a gallinacean with very variable laying capacity. Both sexes display carotenoid-based ornamentation that gradually fades throughout the laying period. Here, the redness of beak and eye rings of captive males was intensified after mating by means of paint. The proportion of females that laid eggs did not differ between treatments. Amongst laying females, those mated with colour-enhanced males (experimental females) tended to lay earlier and produced significantly more eggs than controls, but of similar quality (egg mass and composition). We additionally investigated whether male attractiveness influenced egg components depending on the clutch size and laying sequence. The testosterone level in eggs from experimental females was positively related to the laying order, whereas control eggs did not show any trend. Our results provided mixed support for the DAH, but nevertheless revealed that female red-legged partridges may adjust their breeding investment according to male carotenoid-based ornamentation. 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.
E. C. Pariser L. Gilbert N. Hazon K. E. Arnold J. A. Graves 《Behavioral ecology and sociobiology》2012,66(4):519-527
Females are expected to partition resources between offspring in a context-dependent way to maximise total fitness returns
from a reproductive attempt. Female zebra finches (Taeniopygia guttata) vary the allocation of yolk androgens and antioxidants among offspring. Importantly, the balance between androgens and antioxidants
in yolks may be more important than their independent absolute amounts in terms of fitness consequences for developing young.
Therefore, we tested whether the relative allocation of these two resources in yolks varies according to either the Trivers–Willard,
positive or compensatory maternal investment hypothesis. We manipulated male attractiveness using coloured leg bands (red-banded
males appear attractive; green-banded males, unattractive) and measured yolk androgens and antioxidants in each egg, egg sex,
clutch sex ratio and female condition. While female zebra finches manipulated the balance of androgens and antioxidants within
and between clutches in response to mate attractiveness, offspring sex and their own condition, they did not do so in a way
that consistently followed any of the hypotheses. Mothers paired with unattractive males allocated a larger antioxidant/androgen
ratio to daughters than sons. This pattern was reversed when paired to an attractive male; sons received a larger antioxidant/androgen
ratio than daughters. We also found offspring sex ratio decreased with increasing female condition for unattractive males,
but not for attractive males. However, without knowing the fitness consequences of the balance of different egg constituents,
it is difficult to interpret the patterns consistently in terms of the Trivers–Willard, compensatory and positive investment
hypotheses. 相似文献
9.
Diego Rubolini Maria Romano Roberta Martinelli Nicola Saino 《Behavioral ecology and sociobiology》2006,59(3):344-352
Androgen hormones of maternal origin contained in the eggs of avian species are considered to have positive effects on offspring
characteristics and performance. However, negative consequences have also been reported, suggesting that mothers may experience
a trade-off between beneficial and detrimental effects of egg androgens to offspring fitness. We studied the effects of elevated
yolk testosterone (T) concentration on survival, development and phenotype of male and female yellow-legged gull (Larus michahellis) chicks by injecting egg yolks with physiological doses of the hormone. Elevated yolk T resulted in a male-biased post-hatching
sex ratio, T-treated clutches producing a greater proportion of males compared to control ones at day 4 post-hatching, likely
resulting from a reduction of female embryonic survival, whereas no effect of hormone treatment on hatching success or short-term
chick survival was observed. In addition, T depressed post-hatching body mass in both sexes but had no effects on the intensity
of the cell-mediated immune response or skeletal growth. No sex differences in egg characteristics or chick phenotype were
detected. Time to hatching was not affected by T, but females originating from first laid eggs hatched earlier than males
of the same laying order, independently of hormone treatment. However, the implications of sex differences in hatching times
are unclear in the study species. Taken together, our results suggest that female yellow-legged gulls may be constrained in
transferring androgens to their eggs by negative consequences on the viability of female offspring and growth of chicks of
the two sexes. 相似文献
10.
Laaksonen T Adamczyk F Ahola M Möstl E Lessells CK 《Behavioral ecology and sociobiology》2011,65(2):257-264
Female birds might be able to manipulate the parental effort of their male partner through elevated transfer of hormones to
the eggs, since these hormones affect many chick traits that males might use as cues for adjusting the level of their investment.
We experimentally studied whether female pied flycatchers Ficedula hypoleuca could manipulate male investment via yolk androgens. There is much more variation in yolk androgen levels between females
than within clutches, and in order to change the androgen levels of the eggs, we swapped whole clutches between nests. To
estimate the androgen levels of the clutch, we measured the androgen content of a single egg per clutch. Females did not succeed
in manipulating male effort using yolk androgens, since there was no relationship between the division of parental care within
a pair and either original or foster egg androgen levels. One of these relationships should have occurred if females were
manipulating males. The proportion of feeding visits by the male was higher when the male was old (55%) than when he was young
(45%) and females laid eggs with higher androgen levels when mated with a young male. Young males did not exhibit any responses
to yolk androgen levels either, which indicates that females cannot exploit their effort more than that of old males. We suggest
that females may allocate yolk androgens to adjust the growth trajectories of the chicks to poor growing conditions when mated
with young males that are poor providers or occupying a poor territory. 相似文献
11.
Keith W. Sockman Jack Weiss Michael S. Webster Vanessa Talbott Hubert Schwabl 《Behavioral ecology and sociobiology》2008,62(4):617-625
Maternally derived androgen hormones concentrate in avian egg yolks as the yolks grow on the female’s ovary, possibly forming
a basis for important maternal effects in birds. In the American kestrel (Falco sparverius), experimental elevation of yolk androgens in the first-laid egg of a clutch (a-egg) to the concentrations found naturally
in a clutch’s later-laid eggs reduces the growth rate of a-egg nestlings compared to controls. These findings, together with
discoveries from other species that the effects of yolk androgens on growth of female nestlings may differ from their effects
on growth of male nestlings, raise the hypothesis that natural changes in yolk-androgen concentrations with laying order are
ultimately due to a difference between the sexes in their yolk-androgen sensitivity and between early- and late-laid eggs
in their sex ratio. By re-analyzing previously published data and adding to the analysis data from previously unanalyzed blood
samples used for sex determination, we investigated possible sex-specific effects of yolk-androgens in the context of a potential
sex-biased laying order in free-living American kestrels. We used a multi-level, mixed model with a Gompertz function to analyze
growth of nestlings hatching from a-eggs that were control-treated or in which we experimentally elevated yolk-androgen concentrations
shortly after laying to the higher concentrations naturally found in later-laid eggs. We discovered that male nestlings were
more susceptible than female nestlings to growth inhibition by yolk-androgen elevation but did not find a bias in sex ratio
with respect to laying order. Together, these findings do not support the above hypothesis. However, they are consistent with
the hypothesis that sex differences in yolk-androgen sensitivity enable mothers to economically tune reproductive effort to
an individual offspring’s reproductive value, which can vary more for one sex than the other. 相似文献
12.
Diego Rubolini Maria Romano Roberta Martinelli Barbara Leoni Nicola Saino 《Behavioral ecology and sociobiology》2006,59(4):549-560
Mothers may profoundly affect offspring phenotype and performance by adjusting egg components, including steroid hormones.
We studied the effects of elevated prenatal testosterone (T) exposure in the ring-necked pheasant on the expression of a suite
of male and female traits, including perinatal response to stress, immune response, growth, and secondary sexual traits. Prenatal
T levels were increased by injecting the yolk of unincubated eggs with physiological doses of the hormone. Yolk T injection
resulted in a reduced length of male tarsal spurs, a trait which positively predicts male success in intra- and intersexual
selection and viability, whereas no direct effect on male wattle characteristics or plumage traits of either sex was observed.
Female spur length was also negatively affected by T, but to a lesser extent than in males. In addition, the covariation between
male secondary sexual traits, which are reliable quality indicators, differed between T and control males, suggesting that
the manipulation may have altered the assessment of overall male quality by other males and females. In conclusion, the negative
effects of elevated yolk T on spur length, a trait which positively predicts male fitness, coupled with the lack of effects
on growth or other traits in both sexes, provided limited evidence for mothers being subjected to a trade-off between positive
and negative consequences of yolk T deposition on offspring traits and suggest that directional selection for reduced yolk
T levels may occur in the ring-necked pheasant. 相似文献
13.
Diego Rubolini Roberto Ambrosini Maria Romano Manuela Caprioli Mauro Fasola Andrea Bonisoli-Alquati Nicola Saino 《Behavioral ecology and sociobiology》2009,63(12):1809-1819
Non-random sex allocation may occur whenever the expected reproductive value of sons and daughters differs, as is the case when the sexes differ in susceptibility to environmental conditions or maternal effects (e.g. egg size and hatch order). Under such circumstances, covariation between egg and clutch characteristics and egg sex may be expected, and this covariation should vary with maternal state or ecological conditions. In this 2-year study (2007–2008), we examined sex allocation in relation to egg and clutch traits in the yellow-legged gull Larus michahellis, a species where male chicks are larger and more susceptible to harsh rearing conditions than female ones. In 2008, eggs were more likely male early in the season in two- but not three-egg clutches, and large eggs were more likely males late in the season. No egg/clutch traits predicted egg sex in 2007. Within-clutch egg mass asymmetry (the difference in egg mass between the first- and last-laid eggs) predicted sex in both years. In 2007, clutches with smaller egg mass variation were more likely to contain males, while in 2008 this relationship held for the last-laid egg and was reversed for the preceding egg(s). Laying order and sex of the previous egg did not predict egg sex, providing no evidence of sex-specific oocyte clustering. Thus, the relationships between egg sex and egg/clutch traits differed among years, suggesting a phenotypically plastic response of females to extrinsic conditions, and involved within-clutch egg mass asymmetry, a trait likely reflecting variation in maternal quality and/or reproductive tactics, which has been largely neglected in previous studies of sex allocation. 相似文献
14.
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
15.
When breeding diet is restricted, domesticated zebra finches,Taeniopygia guttata, produce male-biased primary and secondary sex ratios, but unexpectedly produce unbiased ratios when food is unrestricted. We investigated the primary sex ratios (at laying) of wild zebra finches in southeastern Australia in response to food supplementation and environmental factors predicted to enhance female breeding condition and to bias the primary sex ratio towards daughters. Molecular sexing of all nestlings in 54 complete broods where every egg hatched, failed to show any significant biases from random. Time of egg laying (month, season) and environmental conditions (rainfall, temperature) did not significantly predict variation in the primary sex ratio, but time of breeding did affect clutch size. Wild zebra finches at our colony did not bias their sex allocation as there were no differences in the primary sex ratio and no differences in the numbers and mass of sons and daughters at the end of parental care (day 35–40 post-hatch). Biases in primary sex ratio of our wild population are probably weak or non-existent possibly due to the unpredictable environment and/or multiple contrary selective forces acting on sex ratios. We also investigated the effects of photoperiod, biases in the adult sex ratio, and parental attractiveness on primary sex ratios of semi-domesticated, laboratory zebra finches. Molecular sexing of three-day old embryos from complete clutches, failed to reveal significant biases from random. In contrast to previous studies, sex of eggs did not correlate with laying order and egg mass declined with order, rather than increased. Domestication may be responsible for these differences. 相似文献
16.
Fabrice Dentressangle Lourdes Boeck Roxana Torres 《Behavioral ecology and sociobiology》2008,62(12):1899-1908
Females are expected to vary investment in offspring according to variables that may influence the offspring fitness in a way that optimises her inclusive fitness for a particular context. Thus, when sexual ornaments signal the quality of the male, females might invest in reproduction as a function of the attractiveness of their mate. We tested whether breeding conditions and male feet colour influence reproductive decisions of blue-footed booby females. In the blue-footed booby, male feet colour is a dynamic condition-dependent sexually selected trait that is related to paternal effort. During two consecutive years, an El Niño year (poor breeding conditions) and a year with good breeding conditions, we experimentally reduced male attractiveness by modifying their feet colour after the first egg was laid and recorded female investment in the second egg. We found that, relative to the first egg in the clutch, females laid heavier second eggs during the poor year than during the good year. Females paired with males with duller feet colour reduced second-egg mass and volume and delayed the laying of the second egg, independently of the year. Absolute yolk androstenedione (A4) concentration (but not testosterone, T) in second eggs was higher during a poor year than during a good year. Only during a year with poor breeding conditions, females paired with experimental males decreased the relative A4 concentration (but not T) in the second egg compared to control females. Thus, blue-footed booby females probably favour brood reduction by decreasing egg quality and increasing size asymmetry between chicks when the breeding and the mate conditions are poor. 相似文献
17.
Intra-specific interactions influence egg composition in the lesser black-backed gull (Larus fuscus)
Nanette Verboven Neil P. Evans Liliana D’Alba Ruedi G. Nager Jonathan D. Blount Peter F. Surai Pat Monaghan 《Behavioral ecology and sociobiology》2005,57(4):357-365
Egg composition, which is under maternal control, can have a profound effect on offspring fitness. The presence of maternal testosterone and carotenoids in avian egg yolk, for example, is thought to enhance the development and competitive ability of the offspring and protect the hatching and growing chick against oxidative stress. Egg quality often differs between females and such variation can be due to differences in maternal social environment, e.g. breeding density. However, this is confounded by the possibility that the quality of individuals breeding in high- or low-density areas may vary. We tested if maternal social environment influences egg composition in a colonial seabird, the lesser black-backed gull (Larus fuscus). To control for confounding effects of female quality, we experimentally manipulated maternal social environment during egg formation. We increased the frequency of intra-specific interactions (i.e. aggressive encounters with conspecifics other than nest mates) in which the females were involved, by placing an elevated platform in their territory. Females that took part in more intra-specific interactions produced a heavier last egg, but the yolk testosterone concentration in eggs laid by control and experimental females did not differ. Differences in yolk testosterone concentration in relation to embryo sex were found neither in the control nor in the experimental group. In contrast, within the control group, eggs with a male embryo contained more carotenoids than eggs with a female embryo. Moreover, experimental females that had been involved in more intra-specific interactions produced female eggs with higher carotenoid levels compared to female eggs of control birds. An experimental increase in carotenoid levels was not observed in eggs containing a male embryo. Our results suggest that intra-specific interactions experienced by female birds during egg formation can influence conditions for embryonic development.Communicated by J. Graves 相似文献
18.
Suvi Ruuskanen Esa Lehikoinen Mikko Nikinmaa Heli Siitari Wolfgang Waser Toni Laaksonen 《Behavioral ecology and sociobiology》2013,67(3):361-372
The hormonal environment during early development, such as maternally derived androgens in bird eggs, shapes the development of the offspring in ways that may have important long-term consequences for phenotype and behavior and, ultimately, fitness. We studied the long-term effects of yolk androgens on several phenotypic and physiological traits in male and female pied flycatchers (Ficedula hypoleuca) by experimentally elevating yolk androgen levels and rearing birds in common-garden environment in captivity. We found that high yolk androgen levels increased the basal metabolic rates in both females and males in adulthood. High yolk androgen levels did not affect male melanin coloration or plumage ornaments, or timing or speed of moult in either sex. No effect of androgen treatment on cell-mediated or humoral immune response was found in either sex. Covariation among the measured phenotypic traits was further not altered by androgen treatment. Our results suggest that exposure to high androgen levels can have long-lasting effects on some offspring traits, but do not seem to lead to different phenotypes. Furthermore, the role of yolk androgens affecting sexually selected male traits in our study species seems to be minor. The fitness consequences of yolk androgen-induced higher metabolic rates remain to be studied. 相似文献
19.
Although evidence is accumulating on the adaptive function of female ornamentation, very little is known about maternal allocation
decisions involving sexual signaling and other reproductive functions. Blue egg coloration has been suggested as a sexually
selected signal of female quality to males, and some recent studies are in accordance with this hypothesis. Blue eggshell
coloration results from the deposition of biliverdin pigment by laying females, which is a potent antioxidant. Thus, egg pigmentation
should be costly in terms of antioxidants, an assumption of the signaling hypothesis that has not been tested yet. We induced
increased reproductive effort in a set of female pied flycatchers Ficedula hypoleuca through nest removal and measured egg pigmentation and plasma antioxidant levels in relation with a control group. Experimental
females showed a negative association between egg color and plasma antioxidant levels, while there was no relationship for
control birds. This supports that egg pigmentation is costly in terms of general antioxidant defenses and suggests a tradeoff
between the allocations to both traits. Furthermore, experimental females with more colorful eggs raised more fledglings,
especially when breeding early. Controls did not show a relationship between egg color and reproductive success. Females laying
more colorful eggs could have shifted their allocation decisions towards current reproduction, at the expense of their own
antioxidant defenses. Our results highlight that blue egg coloration is a life-history trait, subject to tradeoffs with other
attributes, and seems to be especially informative under harsh breeding conditions. 相似文献
20.
Adjusting the timing of hatching to changing environmental conditions has fitness costs in blue tits
After laying the first egg, a bird can, to a certain extent, adjust the hatching date of the brood to environmental conditions.
However, costs of this adjustment have remained largely unexplored. We studied potential costs of hatching delay in a population
of blue tits in southern Finland. We explored the factors underlying hatching delay and investigated the association between
hatching delay, clutch hatchability and female body condition. Finally, we reciprocally cross-fostered a large number of broods
irrespective of their experienced hatching delay to address possible downstream effects of hatching delay on developmental
parameters in offspring. We found that hatching delay was associated with early laying dates and low mean temperatures during
the egg-laying phase. Furthermore, we found evidence that delayed hatching negatively affected the breeding performance. Hatchability
of the clutch was lowered and the breeding female was energetically impaired, resulting in smaller clutch sizes, lower female
body mass at hatching and lowered survival of nestlings reared in nests that had experienced a long hatching delay. In addition,
delayed hatching had a significant negative effect on the body mass of nestlings prior to fledging. However, ultimately we
did not find evidence that delayed hatching affected survival of the breeding female nor recruitment of fledglings in the
local breeding population. Our study demonstrates that environmental conditions during egg laying can have lasting effects
throughout the breeding and nestling phase. Furthermore, our results emphasize the importance of energetic tradeoffs by breeding
females during the early breeding phase to manage reproductive costs. 相似文献