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1.
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
2.
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
3.
Joanna Rutkowska Tomasz Wilk Mariusz Cichoń 《Behavioral ecology and sociobiology》2007,61(8):1211-1217
There is accumulating evidence that maternal hormones may play a role in offspring sex adjustment, but little is known about
the costs of such hormone-mediated mechanisms. Recent studies have reported sex-specific effects of hormones on offspring
viability. Specifically, we previously found that elevating the plasma androgen level in mothers results in a male-biased
offspring primary sex ratio, but it affects the viability of sons negatively and daughters positively in zebra finches (Taeniopygia guttata; Rutkowska and Cichoń, Anim Behav, 71:1283–1288, 2006). In this study, we studied further fitness consequences of exposure
to elevated yolk androgen levels in zebra finches. We measured growth rate and cellular immune response of nestlings that
hatched from eggs laid by females injected with testosterone during egg laying and nestlings of unaffected control females.
We found that sons of testosterone-treated females grew slower in comparison to sons of control females. The significant interaction
between experimental group and offspring sex indicates that sons of testosterone-treated mothers suffered impaired immune
responsiveness while daughters seemed to benefit from elevated androgen level in terms of enhanced immune responsiveness.
We found no effects of androgens on offspring performance at adulthood—neither fecundity of females nor attractiveness of
males was affected. We conclude that the benefits of biasing sex ratio towards males by increasing androgen level in the yolk
may be limited due to negative effects on male offspring performance early in life. 相似文献
4.
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
5.
Ruuskanen S Helle S Ahola M Adamczyck F Möstl E Laaksonen T 《Behavioral ecology and sociobiology》2011,65(5):983-994
Early androgen exposure is known to have long-lasting effects on phenotype, behaviour and even fitness, but difficulties in
measuring the exposure hinders the study of its importance in evolutionary context. Digit ratios have been highlighted as
a potential easy-to-measure indicator of early steroid exposure, as they have been suggested to reflect steroid, mainly testosterone
levels during prenatal development. However, evidence for digit ratios reflecting early steroid levels is weak, as experimental
studies, especially in wild populations, are scarce. We studied the association between maternally derived yolk androgens
and digit ratios (2D:4D, 2D:3D and 3D:4D) using both correlative data and a rather high level of experimental elevation of
yolk androgens in a passerine bird, the pied flycatcher (Ficedula hypoleuca). We also examined whether digit ratios have indicator value in an evolutionary context by studying correlations between
digit ratios and reproductive traits, secondary sexual traits and exploratory behaviour. We did not find any association between
digit ratios and yolk androgen level either in correlative or experimental data. Digit ratios were neither related to any
of the reproductive and secondary sexual traits or exploratory behaviour measured. There was, however, a sex difference in
2D:3D and 3D:4D of adult birds (due to second and fourth digits being shorter in females), which was not apparent in fledglings
or captivity-raised juveniles. This suggests that either the sex difference may develop as late as during the sexual maturation
for breeding. These results indicate that, in this species, digit ratios are not reliable markers of maternally derived yolk
androgen exposure and that they bear little relevance as correlates of the adaptive traits we measured. 相似文献
6.
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
7.
Andrea Bonisoli-Alquati Diego Rubolini Manuela Caprioli Roberto Ambrosini Maria Romano Nicola Saino 《Behavioral ecology and sociobiology》2011,65(9):1779-1790
Transfer of maternal hormones to the eggs is a major source of offspring phenotypic variation. The developmental and organizational
effects of egg hormones can extend into adulthood and affect behavioral and morphological traits involved in sexual and reproductive
behavior, with important consequences for offspring fitness. In this study, we injected testosterone (T) in egg albumen of
captive ring-necked pheasant (Phasianus colchicus) eggs. We then assessed the consequences for chick growth, cell-mediated immunity, and multiple male secondary sexual traits
at maturity by comparison with a control group. We also compared the covariation between traits in the two experimental groups.
We found that control males had redder wattles than males from T-injected eggs, suggesting that attractiveness and reproductive
success of the offspring might vary depending on maternal transfer of T to the eggs. T treatment also modified the covariation
between cell-mediated immunity and wattle coloration and between the area of the wattle and the expression of another secondary
sexual trait, the ear tufts. These effects are likely to translate into fitness differences among the offspring if mate acquisition
depends on the simultaneous expression of several traits that are differentially affected by the same maternal contribution.
Maternal effects mediated by egg hormones might affect the fitness of the offspring not only by directional modification of
phenotypic traits, but also by facilitating or inhibiting their covariation. This suggests the possibility that female choice
based on the relative expression of multiple secondary sexual traits exerts a pressure on how maternal transfer of androgens
contributes to developmental programs. 相似文献
8.
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
9.
Diego Gil Alfonso Marzal Florentino de Lope Marisa Puerta Anders P. Møller 《Behavioral ecology and sociobiology》2006,60(1):96-100
Female birds deposit in the yolks of eggs substantial amounts of androgens, such as testosterone and androstenedione. These
androgens have been shown to speed up nestling development, induce a fast development of ornaments and increase dominance
in adults. Experiments in several species have reported that females invest greater amounts of androgens in the eggs fathered
by attractive males, suggesting that yolk androgen is a costly investment for either the offspring or the mother. There is
some evidence that nestling immunocompetence may be partially suppressed by high levels of yolk androgens, but it is not known
whether this is also the case for females. We tested this hypothesis in the house martin by inducing an immune challenge through
an injection of sheep red blood cells, a standard challenge of the humoral immune system. Experimental birds laid eggs with
lower amounts of yolk androstenedione than controls, and there was a similar non-significant trend for testosterone. Furthermore,
the probability of laying a replacement clutch was higher for birds that had laid a first clutch with relatively high levels
of yolk testosterone. These results suggest that yolk androgen deposition is limited by immune costs in the female, and that
only females in good condition may afford to invest high levels of androgen in eggs in this species. 相似文献
10.
An organism’s pattern of development can have important long-term fitness effects. In species where the sexes differ in size
or other phenotypic traits, they may also have different optimal developmental rates. This influences both parental sex allocation
strategies and susceptibility of the sexes to early developmental conditions. However, sex differences in developmental rate
and vulnerability to environment during the embryonic period are not well understood. In birds, sibling competition and hatching
asynchrony may select for accelerated embryonic development of the last offspring in order to reduce their competitive disadvantage
after hatching. They may advance their hatching in response to vocal stimuli by the older siblings. It is, however, unclear
whether this flexibility in developmental rates is sex specific. In this study, we experimentally manipulated between-embryo
contact and tested whether this affected the pre-natal developmental rate and post-hatching performance of male and female
offspring from last-laid eggs in the herring gull. Post-hatching performance was measured both in competitive and non-competitive
situations. Among young incubated in isolation, males hatched faster than females, but both sexes fledged in similar, relatively
good condition. Among young incubated with normal between-embryo contact, hatching time did not differ between sexes, but
males fledged in poorer condition than females, regardless of whether they were reared singly or in a brood. These results
suggest that male and female offspring differ in their ability to mitigate the costs of hatching asynchrony. 相似文献
11.
Hormones of maternal origin transferred to the eggs of oviparous species have been shown to significantly affect offspring development. Furthermore, there is now increasing evidence that these effects may last into adulthood. This underlines the persistence of yolk hormone-mediated maternal effects as well as their trans-generational potential as these changes may involve fitness-related traits such as mate choice behaviour, reproductive traits and longevity. Here, we tested the potential of yolk testosterone to affect sexual selection by experimentally increasing the yolk testosterone levels via egg injections. We focused on two central axes of sexual selection, male–male competition for access to a female (intra-sexual selection) and female mate choice behaviour (inter-sexual selection), using canaries (Serinus canaria) as a model species. Neither male agonistic behaviour nor access to the opposite sex, as measured in staged male–male encounters in the presence of a female, were affected by experimentally elevating yolk testosterone levels. We did not find any evidence for effects on female mate choice behaviour either, given the lack of significant effects on mate choice activity, consistency in female mate choice or choosiness. In conclusion, our results indicate that the consequences of yolk testosterone for sexual selection through changes in behavioural traits, which are expressed during pair formation or male–male competition, are probably limited. 相似文献
12.
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
13.
Vladimír Remeš 《Behavioral ecology and sociobiology》2011,65(6):1257-1266
Females can adaptively adjust phenotype of their offspring via deposition of various compounds into eggs, including androgens
and other hormones. Here, I investigated how egg yolk androgens (testosterone and androstenedione) related to environmental
conditions and parental traits in the great tit (Parus major) across three breeding seasons. Male and female traits studied included age, condition and multiple feather ornaments, both
carotenoid- and melanin-based (carotenoid and UV chroma of yellow breast feathers, area of black breast band and white cheek
immaculateness). Yolk mass increased with laying temperature, laying date and area of male black breast band. Concentration
of androgens increased with breeding density, territory quality and carotenoid chroma of male yellow breast feathers and was
higher in mates of 1 year old as compared to older males. Yolk androgens were not related to any of the female traits analysed.
These patterns were thus consistent with (1) social and environmental effects on yolk mass and composition and (2) both positive
and negative differential allocation strategies of resource allocation in females. Overall, male traits were the most important
predictors of egg yolk characteristics in this socially monogamous songbird. 相似文献
14.
Male mating behaviors harmful to females have been described in a wide range of species. However, the direct and indirect fitness consequences of harmful male behaviors have been rarely quantified for females and their offspring, especially for long-lived organisms under natural conditions. Here, lifetime and intergenerational consequences of harmful male interactions were investigated in female common lizards (Lacerta vivipara) using field experiments. We exposed females to male harm by changing the population sex ratio from a normal female-biased to an experimental male-biased sex ratio during the first experimental year. Thereafter, females and their first generation of offspring were monitored during two additional years in a common garden with a female-biased sex ratio. We found strong immediate fitness costs and lower lifetime reproductive success in females subjected to increased male exposure. The immediate fitness costs were partly mitigated by direct compensatory responses after exposure to male excess, but not by indirect benefits through offspring growth, offspring survival, or mating success of offspring. These results support recent empirical findings showing that the direct costs of mating are not outweighed by indirect benefits. 相似文献
15.
Dieter Heylen Wendt Müller Ton G. G. Groothuis Erik Matthysen 《Behavioral ecology and sociobiology》2012,66(2):287-293
In birds as in many other taxa, parasites can have deleterious effects on offspring development. Therefore, avian mothers
have evolved responses to counteract parasite virulence in offspring via transgenerational defense mechanisms that is the
transfer of immune-enhancing substances such as antibodies to their eggs. Another maternal pathway is suggested by the finding
that infested great tit mothers produced eggs with lower androgens, since these yolk androgens are immunosuppressive and potentially
affect parasite susceptibility of the nestlings. However, whether this pathway is a specific adaptation to infestation with
parasites that affect the offspring or an epiphenomenon of lower androgen production in the female due to the parasite effects
on the mother itself is as yet unclear. In this study we infested female great tits (Parus major) with sheep ticks (Ixodes ricinus), which are nonnidicolous ectoparasites with low vertical transmission capability, and evaluated the effects on yolk androgen
deposition. Tick-infested females did not significantly reduce their deposition of androgens (androstenedione (A4) and testosterone) compared to tick-reduced females, which is in contrast to a previous study showing a lowered deposition
of A4 and testosterone when females were exposed to the nidicolous hen flea. Thus, females alter their hormone deposition, and
thus likely offspring phenotype, when exposed to parasites that also form the parasitic environment of their offspring, but
not when temporarily infested with the field-dwelling sheep ticks with low transmission capability. This suggests that selection
favored the evolution of an adaptive transgenerational effect by acting mainly on the parasite-induced maternal effect. 相似文献
16.
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
17.
The presumed trade-off between offspring size and quality predicted by life history theory is often invoked to explain the wide range of propagule sizes observed in animals and plants. This trade-off is broadly supported by intraspecific studies but has been difficult to test in an interspecific context, particularly in animals. We tested the fitness consequences of offspring size both intra- and interspecifically for seven species of ascidians (sessile, suspension-feeding, marine invertebrates) whose offspring volumes varied over three orders of magnitude. We measured two major components of fitness, juvenile growth rates and survival, in laboratory and field experiments encompassing several food conditions. Contrary to the predictions of life history theory, larger offspring size did not result in higher rates of growth or survival, and large offspring did not perform better under nutritional stress, either intraspecifically or interspecifically. In fact, two of the four species with small offspring grew rapidly enough to catch up in size to the species with large offspring in as little as eight weeks, under wild-type food conditions. Trade-offs between growth potential and defense may overwhelm and obscure any trade-offs between offspring size and survival or growth rate. While large initial size may still confer a competitive advantage, we failed to detect any consequences of interspecific variation in initial size. This implies that larger offspring in these species, far from being inherently superior in growth or survival, require compensation in other aspects of life history if reproductive effort is to be efficient. Our results suggest that the importance of initial offspring size is context dependent and often overestimated relative to other life history traits. 相似文献
18.
Jenni E Pettay Anna Rotkirch Alexandre Courtiol Markus Jokela Virpi Lummaa 《Behavioral ecology and sociobiology》2014,68(1):135-143
The fitness benefits of multiple mating determine the strength of sexual selection in each sex. This is traditionally quantified by the number of offspring born to once versus multiply mated individuals. In species with (bi)parental care, however, this measure may overestimate the benefits of multiple mating since having several mates can increase offspring number but decrease offspring quality. We analyzed short- and long-term fitness consequences of multiple marriages for both sexes in humans in preindustrial Finnish populations, where monogamy was socially enforced and remarriage was possible only after widowhood. Remarriage increased the lifetime number of offspring sired by men by lengthening their reproductive span but was unrelated to the lifetime number of births for women. However, neither men's nor women's long-term fitness, measured as their number of grandchildren, was significantly increased or decreased by remarriage. These associations were not modified by individual wealth. Our results suggest that despite increasing the number of offspring sired by men, the long-term fitness benefits of serial monogamy may be negligible for both sexes when parental investment is crucial for offspring success and continues to adulthood. They also demonstrate the importance of incorporating long-term fitness measures when quantifying the benefits of mating and reproductive strategies. 相似文献
19.
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
20.
Despite the consensus that mate choice acts as a mechanism for selection of secondary sexual traits, the evolutionary forces affecting mate preferences themselves remain controversial. In this study, we first demonstrated selection acting directly on the mate preferences of monogamous male oldfield mice, Peromyscus polionotus rhoadsi. One group of male oldfield mice were allowed to express a social preference between two potential mates, and were subsequently paired with either their preferred or rejected female. Among these pairs, those containing preferred females produced more offspring than did those containing rejected females. We next demonstrated that this fitness advantage depended primarily on compatibility between the members of a mated pair. A second group of male oldfield mice were not allowed the opportunity to express a social preference between potential mates. Rather, these males were paired with females that had been either preferred or rejected by males in the first group. Among these pairs, those containing preferred females did not produce more offspring than those containing rejected females. In other words, individual mate preferences had fitness consequences only for those males that expressed them, demonstrating that these preferences were based primarily on compatibility between mates. 相似文献