Exogenous and endogenous corticosterone alter feather quality

DesRochers, David W.; Reed, J. Michael; Awerman, Jessica; Kluge, Jonathan A.; Wilkinson, Julia B.; Griethuijsen, Linnea I. van; Aman, Joseph F; Romero, L. Michael

doi:10.1016/j.cbpa.2008.08.034

Cited by 114 publications

(139 citation statements)

References 37 publications

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“…However, endogenous elevations of CORT via exposing birds to psychological or physical stressors have yielded mixed results. Psychological stressors had no effect on feather quality but European starlings subjected to food restriction grew feathers of lower mass in one study (Strochlic and Romero, 2008) and weaker feathers in a second (DesRochers et al, 2009). …”

Section: The Molecular Trade-off Hypothesismentioning

confidence: 89%

“…The slower, less resource-intensive feather growth in rock doves may allow maintenance of the hormonal stress response, consistent with a protein-based trade-off (Romero and Wingfield, 2001). Subsequent experiments support this molecular trade-off hypothesis (DesRochers et al, 2009;Romero et al, 2005;Strochlic and Romero, 2008), though plausible alternatives such as energyor behavior-based trade-offs and more direct mechanistic hypotheses have not been formally considered. Behavioral, energetic or resource-based conflicts between maintenance processes such as molt and the stress response may have influenced the evolution of life cycle schedules.…”

Section: Introductionmentioning

confidence: 97%

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Physiological trade-offs in self-maintenance: plumage molt and stress physiology in birds

Cornelius

Perfito

Zann

et al. 2011

Journal of Experimental Biology

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SUMMARYTrade-offs between self-maintenance processes can affect life-history evolution. Integument replacement and the stress response both promote self-maintenance and affect survival in vertebrates. Relationships between the two processes have been studied most extensively in birds, where hormonal stress suppression is down regulated during molt in seasonal species, suggesting a resource-based trade-off between the two processes. The only species found to differ are the rock dove and Eurasian tree sparrow, at least one of which performs a very slow molt that may reduce resource demands during feather growth, permitting investment in the stress response. To test for the presence of a molt-stress response trade-off, we measured hormonal stress responsiveness during and outside molt in two additional species with extended molts, red crossbills (Loxia curvirostra) and zebra finches (Taeniopygia guttata). We found that both species maintain hormonal stress responsiveness during molt. Further, a comparative analysis of all available species revealed a strong relationship between molt duration and degree of hormonal suppression. Though our results support trade-off hypotheses, these data can also be explained by alternative hypotheses that have not been formally addressed in the literature. We found a strong relationship between stress suppression and seasonality of breeding and evidence suggesting that the degree of suppression may be either locally adaptable or plastic and responsive to local environmental conditions. We hypothesize that environmental unpredictability favors extended molt duration, which in turn allows for maintenance of the hormonal stress response, and discuss implications of a possible trade-off for the evolution of molt schedules. Supplementary material available online at

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Section: The Molecular Trade-off Hypothesismentioning

confidence: 89%

Section: Introductionmentioning

confidence: 97%

Physiological trade-offs in self-maintenance: plumage molt and stress physiology in birds

Cornelius

Perfito

Zann

et al. 2011

Journal of Experimental Biology

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“…The tendency of the overlappers to lose more body condition over time suggests that the costs of the overlap were not fully compensated, even under the benign conditions of captivity. It is possible, however, that aspects of feather quality could have been compromised in overlappers, such as feather mass or structure (Dawson et al, 2000;DesRochers et al, 2009;De la Hera et al, 2010;Strochlic and Romero, 2008;Maenniste and Horak, 2011). Further characterizations of feather structural properties in relation to molt/breeding overlap are needed to resolve this question.…”

Section: Discussionmentioning

confidence: 99%

Molt–breeding overlap alters molt dynamics and behavior in zebra finches,Taeniopygia guttata castanotis

Echeverry‐Galvis

Hau

2012

Journal of Experimental Biology

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SUMMARYCostly events in the life history cycle of organisms such as reproduction, migration and pelage/plumage replacement are typically separated in time to maximize their outcome. Such temporal separation is thought to be necessitated by energetical trade-offs, and mediated through physiological processes. However, certain species, such as tropical birds, are able to overlap two costly life history stages: reproduction and feather replacement. It has remained unclear how both events progress when they co-occur over extended periods of time. Here we determined the consequences and potential costs of such overlap by comparing molt and behavioral patterns in both sexes of captive zebra finches (Taeniopygia guttata castanotis) that were solely molting or were overlapping breeding and molt. Individuals overlapping the early stages of breeding with molt showed a roughly 40% decrease in the growth rate of individual feathers compared with birds that were molting but not breeding. Further, individuals that overlapped breeding and molt tended to molt fewer feathers simultaneously and exhibited longer intervals between shedding consecutive feathers on the tail or the same wing as well as delays in shedding corresponding flight feathers on opposite sides. Overlapping individuals also altered their time budgets: they devoted more than twice the time to feeding while halving the time spent for feather care in comparison to molt-only individuals. These data provide experimental support for the previously untested hypothesis that when molt and reproduction overlap in time, feather replacement will occur at a slower and less intense rate. There were no sex differences in any of the variables assessed, except for a tendency in females to decline body condition more strongly over time during the overlap than males. Our data indicate the existence of major consequences of overlapping breeding and molt, manifested in changes in both molt dynamics and time budgets of both sexes. It is likely that under harsher conditions in natural environments such consequences will be more severe and may result in fitness consequences.

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“…The rate of feather keratinization is strongly influenced by the initial amount and concentration of keratin monomers [67], which in turn is mostly limited by keratin gene transcription and mRNA abundance [68]. Given that keratin gene expression is regulated by various transcription factors that are highly responsive to extracellular condition and hormones [69], and keratinization itself is sensitive to the pH of the cellular environment [67], this crucial step in nanostructural organization is likely to be sensitive to, and therefore indicative of, developmental stressors and individual condition [70][71][72]. In summary, based on the timing and steps of the organization of colour-producing nanostructures, our evidence strongly opposes the suggestion that nanostructural organization results from active cellular processes, instead pointing to the role of energy-minimizing entropic interactions for achieving such patterns.…”

Section: Sexual Selection and The Evolution Of Iridescent Plumagementioning

confidence: 99%

Nanostructural self-assembly of iridescent feather barbules through depletion attraction of melanosomes during keratinization

Maia

Macêdo

Shawkey

2011

J. R. Soc. Interface.

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Avian plumage colours are model traits in understanding the evolution of sexually selected ornamental traits. Paradoxically, iridescent structural colours, probably the most dazzling of these traits, remain the most poorly understood. Though some data suggest that expression of bright iridescent plumage colours produced by highly ordered arrays of melanosomes and keratin is condition-dependent, almost nothing is known of their ontogeny and thus of any developmental mechanisms that may be susceptible to perturbation. Here, we use light and electron microscopy to compare the ontogeny of iridescent male and non-iridescent female feathers in blue-black grassquits. Feather barbules of males contain a single layer of melanosomes bounded by a thin layer of keratin-producing blue iridescent colour, while those of females contain disorganized melanosomes and no outer layer. We found that nanostructural organization of male barbules occurs late in development, following death of the barbule cell, and is thus unlikely to be under direct cellular control, contrary to previous suggestions. Rather, organization appears to be caused by entropically driven self-assembly through depletion attraction forces that pin melanosomes to the edge of barbule cells and to one another. These forces are probably stronger in developing barbules of males than of females because their melanosomes are (i) larger, (ii) more densely packed, and (iii) more homogeneously distributed owing to the more consistent shape of barbules during keratinization. These data provide the first proposed developmental pathway for iridescent plumage colours, and suggest that any condition dependence of iridescent barbules is likely driven by factors other than direct metabolic cost.

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Exogenous and endogenous corticosterone alter feather quality

Cited by 114 publications

References 37 publications

Physiological trade-offs in self-maintenance: plumage molt and stress physiology in birds

Physiological trade-offs in self-maintenance: plumage molt and stress physiology in birds

Molt–breeding overlap alters molt dynamics and behavior in zebra finches,Taeniopygia guttata castanotis

Nanostructural self-assembly of iridescent feather barbules through depletion attraction of melanosomes during keratinization

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