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Stephan J. Schoech - One of the best experts on this subject based on the ideXlab platform.
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Influence of corticosterone treatment on nestling begging in Florida scrub-jays (Aphelocoma coerulescens)
General and Comparative Endocrinology, 2017Co-Authors: Emily K. Elderbrock, Thomas W. Small, Stephan J. SchoechAbstract:Abstract Altricial young are dependent on adults for protection and food, and they display nutritional need by begging to elicit feeding from parents. Begging at high levels can be energetically expensive and attract predators; thus, an individual must balance its nutritional needs with these potential costs. Further, because a parent is limited in the amount of food it can provide, begging can contribute to both parent-offspring conflict and sibling-sibling competition. Many extrinsic and intrinsic factors may contribute to begging behavior. One intrinsic factor of interest is corticosterone (CORT), a metabolic hormone hypothesized to play a role in regulating a nestling’s begging behavior. We investigated the hypothesis that increased exposure to CORT influences nestling begging behavior in an altricial species, the Florida scrub-jay ( Aphelocoma coerulescens ). We treated one nestling per treatment nest with a twice-daily dose of exogenous hormone via a CORT-injected waxworm, whereas a second individual received a vehicle-injected waxworm. We monitored individual nestling and adult behavior at all nests with the use of high-definition video cameras on several days during treatment. We found no difference in begging rate between CORT fed and vehicle fed Nestlings within a treatment nest. Further, to determine whether CORT treatment had indirect effects on the entire brood, we monitored additional nests, in which Nestlings were not manipulated. When treatment and controls were compared, overall begging rates of Nestlings in treatment nests were greater than those in control nests. This result suggests that CORT treatment of an individual altered its behavior, as well as that of its siblings.
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corticosterone brood size and hatch order in free living florida scrub jay aphelocoma coerulescens Nestlings
General and Comparative Endocrinology, 2011Co-Authors: Travis E Wilcoxen, Michelle A Rensel, Stephan J. SchoechAbstract:Abstract It is well known that variation in developmental conditions can have profound effects upon lifetime fitness. In altricial avian species, Nestlings undergo a substantial portion of development in the nest after hatching, often in the presence of nest-mates. This can result in the formation of brood hierarchies based on age, size, and competitive ability. Measurement of baseline corticosterone (CORT) levels in developing birds may provide a means to assess whether individuals within a brood experience stress due to sibling competition or nutritional state. However, few studies have attempted to correlate corticosterone concentrations with brood hierarchies in free-living, developing birds. We investigated the degree to which corticosterone levels in nestling Florida scrub-jays ( Aphelocoma coerulescens ) were predicted by brood size, hatching order, and body mass. Nestling corticosterone levels were inversely correlated with body mass but did not differ among brood sizes. Within broods of two, second-hatched Nestlings had lower CORT than first-hatched Nestlings, although there was no effect of hatch order in broods of three or four Nestlings. The results of this study suggest that conditions within the nest, particularly those associated with within-brood hierarchies, are manifested through differential body condition and nestling corticosterone secretion. The consequences of this variation in nestling corticosterone are unknown, but development of the adult phenotype, as well as life-long survival, may be impacted.
Michelle A Rensel - One of the best experts on this subject based on the ideXlab platform.
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corticosterone brood size and hatch order in free living florida scrub jay aphelocoma coerulescens Nestlings
General and Comparative Endocrinology, 2011Co-Authors: Travis E Wilcoxen, Michelle A Rensel, Stephan J. SchoechAbstract:Abstract It is well known that variation in developmental conditions can have profound effects upon lifetime fitness. In altricial avian species, Nestlings undergo a substantial portion of development in the nest after hatching, often in the presence of nest-mates. This can result in the formation of brood hierarchies based on age, size, and competitive ability. Measurement of baseline corticosterone (CORT) levels in developing birds may provide a means to assess whether individuals within a brood experience stress due to sibling competition or nutritional state. However, few studies have attempted to correlate corticosterone concentrations with brood hierarchies in free-living, developing birds. We investigated the degree to which corticosterone levels in nestling Florida scrub-jays ( Aphelocoma coerulescens ) were predicted by brood size, hatching order, and body mass. Nestling corticosterone levels were inversely correlated with body mass but did not differ among brood sizes. Within broods of two, second-hatched Nestlings had lower CORT than first-hatched Nestlings, although there was no effect of hatch order in broods of three or four Nestlings. The results of this study suggest that conditions within the nest, particularly those associated with within-brood hierarchies, are manifested through differential body condition and nestling corticosterone secretion. The consequences of this variation in nestling corticosterone are unknown, but development of the adult phenotype, as well as life-long survival, may be impacted.
Heinz Richner - One of the best experts on this subject based on the ideXlab platform.
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maternal yolk testosterone does not modulate parasite susceptibility or immune function in great tit Nestlings
Journal of Animal Ecology, 2005Co-Authors: Barbara Tschirren, Patrick S Fitze, Verena Saladin, Hubert Schwabl, Heinz RichnerAbstract:Summary 1. Maternal yolk hormones can enhance the development and phenotypic quality of nestling birds. Nevertheless, within species large differences in yolk androgen concentrations among clutches are observed. This differential allocation of maternal yolk hormones might be explained by a trade-off between beneficial effects of yolk androgens and their associated costs. 2. Potential costs include an increased susceptibility to parasites in Nestlings exposed to high concentrations of yolk androgens during embryonic development, weaker immune response or increased levels of circulating corticosterone that indirectly reduce immune function. 3. In a field study, we manipulated yolk testosterone in great tit ( Parus major ) eggs and tested the nestling’s susceptibility to ectoparasites as measured by the parasites’ effect on growth, the cellular immune response, and the levels of circulating corticosterone. 4. At the end of the nestling period, Nestlings originating from testosterone-injected eggs were heavier than control Nestlings. This effect was strongest in Nestlings at the end of the size hierarchy, as shown by a significant interaction between hormone treatment and the Nestlings’ size rank within nests. 5. High levels of yolk testosterone promoted growth of the nestling’s body mass similarly in parasite-infested and parasite-free nests, and neither affected the levels of plasma corticosterone, nor the nestling’s cell-mediated immune response. 6. In summary, our results do not show negative short-term effects of high concentrations of yolk testosterone on immune function or parasite susceptibility, but emphasize that maternal investment via deposition of yolk testosterone can promote fitnessrelated growth and development of Nestlings.
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carotenoid based nestling colouration and parental favouritism in the great tit
Oecologia, 2005Co-Authors: Barbara Tschirren, Patrick S Fitze, Heinz RichnerAbstract:While elaborate carotenoid-based traits in adult birds may have evolved as honest signals of individual quality in the context of sexual selection or other social interactions, the function of carotenoid-based colours in juveniles is less well understood. We investigated the hypothesis that carotenoid-based nestling colouration has evolved in response to parental preference of intensely coloured offspring during food provisioning. In a field experiment, we manipulated nestling plumage colouration by a carotenoid-supplementation and analysed the parental food provisioning behaviour before feather appearance and at the end of the nestling stage. Carotenoids per se did not influence the nestling’s begging behaviour or parental feeding decisions and we found no evidence that carotenoid-based colouration in nestling great tits has a signalling function in parent-offspring interactions. Parents did not discriminate between intensely coloured and control offspring in their food provisioning and in accordance with this finding intensely coloured Nestlings were not heavier or larger at the end of the nestling stage. Alternative explanations for the evolution of carotenoid-based colours in nestling birds are discussed.
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effects of common origin and common environment on nestling plumage coloration in the great tit parus major
Evolution, 2003Co-Authors: Mathias Kolliker, Patrick S Fitze, Heinz RichnerAbstract:Carotenoids cannot be synthesized by birds and thus have to be ingested with food, suggesting that carotenoid-based plumage coloration is environmentally determined. However signaling functions ascribed to plumage imply that plumage coloration is the outcome of an evolutionary process based on genetic variation. By means of a cross-fostering design we show significant effects of both a common rearing environment and the brood from which a nestling originally came from (common origin) on the plumage coloration of nestling great tits (Parus major). This demonstration of origin-related variation in carotenoid-based plumage coloration suggests that the observed variation of the trait has a partial genetic basis. Consistent with environmental determination of this trait, we also found a significant positive correlation between the color saturation of Nestlings and their foster-father's plumage. There was no significant correlation between nestling plumage coloration and the food quantity provided to the Nestlings by the male, the female, or both parents. This suggests that the nestling-foster father correlation arises by the carotenoid quantity ingested rather than the food quantity per se. No significant nestling-true father correlation was found, which suggests that nestling plumage coloration did not indirectly evolve due to sexual selection. Consistent with this result there was no significant correlation between the nestling's plumage color and its coloration as a breeding adult the following year, suggesting that nestling plumage color is a different trait than the first year plumage.
Patrick S Fitze - One of the best experts on this subject based on the ideXlab platform.
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maternal yolk testosterone does not modulate parasite susceptibility or immune function in great tit Nestlings
Journal of Animal Ecology, 2005Co-Authors: Barbara Tschirren, Patrick S Fitze, Verena Saladin, Hubert Schwabl, Heinz RichnerAbstract:Summary 1. Maternal yolk hormones can enhance the development and phenotypic quality of nestling birds. Nevertheless, within species large differences in yolk androgen concentrations among clutches are observed. This differential allocation of maternal yolk hormones might be explained by a trade-off between beneficial effects of yolk androgens and their associated costs. 2. Potential costs include an increased susceptibility to parasites in Nestlings exposed to high concentrations of yolk androgens during embryonic development, weaker immune response or increased levels of circulating corticosterone that indirectly reduce immune function. 3. In a field study, we manipulated yolk testosterone in great tit ( Parus major ) eggs and tested the nestling’s susceptibility to ectoparasites as measured by the parasites’ effect on growth, the cellular immune response, and the levels of circulating corticosterone. 4. At the end of the nestling period, Nestlings originating from testosterone-injected eggs were heavier than control Nestlings. This effect was strongest in Nestlings at the end of the size hierarchy, as shown by a significant interaction between hormone treatment and the Nestlings’ size rank within nests. 5. High levels of yolk testosterone promoted growth of the nestling’s body mass similarly in parasite-infested and parasite-free nests, and neither affected the levels of plasma corticosterone, nor the nestling’s cell-mediated immune response. 6. In summary, our results do not show negative short-term effects of high concentrations of yolk testosterone on immune function or parasite susceptibility, but emphasize that maternal investment via deposition of yolk testosterone can promote fitnessrelated growth and development of Nestlings.
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carotenoid based nestling colouration and parental favouritism in the great tit
Oecologia, 2005Co-Authors: Barbara Tschirren, Patrick S Fitze, Heinz RichnerAbstract:While elaborate carotenoid-based traits in adult birds may have evolved as honest signals of individual quality in the context of sexual selection or other social interactions, the function of carotenoid-based colours in juveniles is less well understood. We investigated the hypothesis that carotenoid-based nestling colouration has evolved in response to parental preference of intensely coloured offspring during food provisioning. In a field experiment, we manipulated nestling plumage colouration by a carotenoid-supplementation and analysed the parental food provisioning behaviour before feather appearance and at the end of the nestling stage. Carotenoids per se did not influence the nestling’s begging behaviour or parental feeding decisions and we found no evidence that carotenoid-based colouration in nestling great tits has a signalling function in parent-offspring interactions. Parents did not discriminate between intensely coloured and control offspring in their food provisioning and in accordance with this finding intensely coloured Nestlings were not heavier or larger at the end of the nestling stage. Alternative explanations for the evolution of carotenoid-based colours in nestling birds are discussed.
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effects of common origin and common environment on nestling plumage coloration in the great tit parus major
Evolution, 2003Co-Authors: Mathias Kolliker, Patrick S Fitze, Heinz RichnerAbstract:Carotenoids cannot be synthesized by birds and thus have to be ingested with food, suggesting that carotenoid-based plumage coloration is environmentally determined. However signaling functions ascribed to plumage imply that plumage coloration is the outcome of an evolutionary process based on genetic variation. By means of a cross-fostering design we show significant effects of both a common rearing environment and the brood from which a nestling originally came from (common origin) on the plumage coloration of nestling great tits (Parus major). This demonstration of origin-related variation in carotenoid-based plumage coloration suggests that the observed variation of the trait has a partial genetic basis. Consistent with environmental determination of this trait, we also found a significant positive correlation between the color saturation of Nestlings and their foster-father's plumage. There was no significant correlation between nestling plumage coloration and the food quantity provided to the Nestlings by the male, the female, or both parents. This suggests that the nestling-foster father correlation arises by the carotenoid quantity ingested rather than the food quantity per se. No significant nestling-true father correlation was found, which suggests that nestling plumage coloration did not indirectly evolve due to sexual selection. Consistent with this result there was no significant correlation between the nestling's plumage color and its coloration as a breeding adult the following year, suggesting that nestling plumage color is a different trait than the first year plumage.
Travis E Wilcoxen - One of the best experts on this subject based on the ideXlab platform.
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corticosterone brood size and hatch order in free living florida scrub jay aphelocoma coerulescens Nestlings
General and Comparative Endocrinology, 2011Co-Authors: Travis E Wilcoxen, Michelle A Rensel, Stephan J. SchoechAbstract:Abstract It is well known that variation in developmental conditions can have profound effects upon lifetime fitness. In altricial avian species, Nestlings undergo a substantial portion of development in the nest after hatching, often in the presence of nest-mates. This can result in the formation of brood hierarchies based on age, size, and competitive ability. Measurement of baseline corticosterone (CORT) levels in developing birds may provide a means to assess whether individuals within a brood experience stress due to sibling competition or nutritional state. However, few studies have attempted to correlate corticosterone concentrations with brood hierarchies in free-living, developing birds. We investigated the degree to which corticosterone levels in nestling Florida scrub-jays ( Aphelocoma coerulescens ) were predicted by brood size, hatching order, and body mass. Nestling corticosterone levels were inversely correlated with body mass but did not differ among brood sizes. Within broods of two, second-hatched Nestlings had lower CORT than first-hatched Nestlings, although there was no effect of hatch order in broods of three or four Nestlings. The results of this study suggest that conditions within the nest, particularly those associated with within-brood hierarchies, are manifested through differential body condition and nestling corticosterone secretion. The consequences of this variation in nestling corticosterone are unknown, but development of the adult phenotype, as well as life-long survival, may be impacted.
