An update on the honesty of melanin‐based color signals in birds

McGraw, Kevin J.

doi:10.1111/j.1755-148x.2008.00454.x

Cited by 144 publications

(131 citation statements)

References 64 publications

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“…Hoi & Griggio 2008;Kingma et al 2008;McGraw 2008;Galván & Møller 2009). The honesty of these signals would be mediated by the relative cost that signallers experience during the trait production or during its maintenance (Hasson 1997;Alonso-Alvarez et al 2009).…”

Section: Discussionmentioning

confidence: 99%

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The expression of melanin-based plumage is separately modulated by exogenous oxidative stress and a melanocortin

2009

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Melanin-based traits involved in animal communication have been traditionally viewed as occurring under strict genetic control. However, it is generally accepted that both genetic and environmental factors influence melanin production. Medical studies suggest that, among environmental factors influencing melanization, oxidative stress could play a relevant role. On the other hand, genetic control would be exerted by the melanocortin system, and particularly by the alpha-melanocyte-stimulating hormone (a-MSH), which triggers the production of eumelanins (black pigments). To determine how the melanocortin system and an exogenous source of oxidative stress interact in the expression of melanin-based plumage, developing red-legged partridges (Alectoris rufa) were manipulated. Some partridges were injected with a-MSH, while other birds received a pro-oxidant molecule (diquat) in drinking water. Controls and birds receiving both treatments were also studied. Both a-MSH-and diquat-treated individuals presented larger eumelanin-based traits than controls, but a-MSHþdiquat-treated birds showed the largest traits, suggesting that oxidative stress and melanocortins promote additive but independent effects. Diquat also induced a decline in the level of a key intracellular antioxidant (glutathione), which is associated with high expression of eumelanin-based signals in other bird species. Some scenarios for the evolution of melanin-based traits in relation to oxidative stress are proposed.

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Section: Discussionmentioning

confidence: 99%

“…In spite of strong support for genetic control in melanin production, melanin-based traits are frequently related to the condition of the bearer, which often fluctuates with environmental conditions (reviewed in Griffith et al 2006;McGraw 2008). But what kind of environmental factors might influence the expression of these traits?…”

Section: Introductionmentioning

confidence: 99%

The expression of melanin-based plumage is separately modulated by exogenous oxidative stress and a melanocortin

2009

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“…There has been considerable speculation on potential mechanisms linking intraspecific signalling ornaments to internal or external states [19,31]. Given the importance of the stress response in transducing emergency events into physiological responses, and the central role CORT plays in those responses [1], it is not surprising that studies have examined CORT as a potential physiological mechanism regulating signalling ornaments [32].…”

Section: Rsblroyalsocietypublishingorg Biol Lett 9: 20130440mentioning

confidence: 99%

The size of a melanin-based plumage ornament correlates with glucocorticoid receptor concentrations in the skin of that ornament

Lattin

Romero

2013

Biol. Lett.

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PhysiologyThe size of a melanin-based plumage ornament correlates with glucocorticoid receptor concentrations in the skin of that ornament Christine R. Lattin and L. Michael Romero Department of Biology, Tufts University, Medford, MA 02155, USA Glucocorticoid hormones such as corticosterone (CORT) play crucial roles in many physiological processes. CORT's actions are primarily mediated via binding to two receptors (glucocorticoid receptors (GRs) and mineralocorticoid receptors (MRs)) in different target tissues. CORT receptors can be independently regulated from circulating hormone titres, from tissue to tissue and even within different regions of the same tissue type. Increasing evidence has shown relationships between circulating CORT and melaninbased pigmentation in skin and feathers, yet to our knowledge, there have been no studies of CORT receptors in the skin of melanized ornaments. Male house sparrows (Passer domesticus) have a black, melanized bib, and evidence suggests that bib size is an important intraspecific signal. We examined the relationship between bib area and tissue sensitivity to CORT by quantifying GR and MR in bib skin and in adjacent paler-feathered belly skin (as a control tissue) at different life-history stages using radioligand binding assays. Males with larger bibs relative to their life-history stage had less GR in bib skin, but not belly skin, than males with smaller bibs. These results suggest a connection between the size of a melanin-based ornament and the underlying tissue's responsiveness to CORT.

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“…[8,9]). However, in addition to melanins, many other factors contribute to organismal coloration, including diet, light conditions, tissue structure, gender and co-expressed pigments [73,74]. Melanosomes occurring in skin and skin derivatives have also been statistically compared to microbodies (or more frequently their imprints) in fossil-associated material, and used to assign hues and colour patterns (e.g.…”

Section: Melanin and Melanosomes In The Fossil Recordmentioning

confidence: 99%

Interpreting melanin-based coloration through deep time: a critical review

et al. 2015

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Colour, derived primarily from melanin and/or carotenoid pigments, is integral to many aspects of behaviour in living vertebrates, including social signalling, sexual display and crypsis. Thus, identifying biochromes in extinct animals can shed light on the acquisition and evolution of these biological traits. Both eumelanin and melanin-containing cellular organelles (melanosomes) are preserved in fossils, but recognizing traces of ancient melanin-based coloration is fraught with interpretative ambiguity, especially when observations are based on morphological evidence alone. Assigning microbodies (or, more often reported, their ‘mouldic impressions’) as melanosome traces without adequately excluding a bacterial origin is also problematic because microbes are pervasive and intimately involved in organismal degradation. Additionally, some forms synthesize melanin. In this review, we survey both vertebrate and microbial melanization, and explore the conflicts influencing assessment of microbodies preserved in association with ancient animal soft tissues. We discuss the types of data used to interpret fossil melanosomes and evaluate whether these are sufficient for definitive diagnosis. Finally, we outline an integrated morphological and geochemical approach for detecting endogenous pigment remains and associated microstructures in multimillion-year-old fossils.

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An update on the honesty of melanin‐based color signals in birds

Cited by 144 publications

References 64 publications

The expression of melanin-based plumage is separately modulated by exogenous oxidative stress and a melanocortin

The expression of melanin-based plumage is separately modulated by exogenous oxidative stress and a melanocortin

The size of a melanin-based plumage ornament correlates with glucocorticoid receptor concentrations in the skin of that ornament

Interpreting melanin-based coloration through deep time: a critical review

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