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Hill GE, Weaver RJ, Powers MJ. Carotenoid ornaments and the spandrels of physiology: a critique of theory to explain condition dependency. Biol Rev Camb Philos Soc 2023; 98:2320-2332. [PMID: 37563787 DOI: 10.1111/brv.13008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 07/27/2023] [Accepted: 07/31/2023] [Indexed: 08/12/2023]
Abstract
Even as numerous studies have documented that the red and yellow coloration resulting from the deposition of carotenoids serves as an honest signal of condition, the evolution of condition dependency is contentious. The resource trade-off hypothesis proposes that condition-dependent honest signalling relies on a trade-off of resources between ornamental display and body maintenance. By this model, condition dependency can evolve through selection for a re-allocation of resources to promote ornament expression. By contrast, the index hypothesis proposes that selection focuses mate choice on carotenoid coloration that is inherently condition dependent because production of such coloration is inexorably tied to vital cellular processes. These hypotheses for the origins of condition dependency make strongly contrasting and testable predictions about ornamental traits. To assess these two models, we review the mechanisms of production of carotenoids, patterns of condition dependency involving different classes of carotenoids, and patterns of behavioural responses to carotenoid coloration. We review evidence that traits can be condition dependent without the influence of sexual selection and that novel traits can show condition-dependent expression as soon as they appear in a population, without the possibility of sexual selection. We conclude by highlighting new opportunities for studying condition-dependent signalling made possible by genetic manipulation and expression of ornamental traits in synthetic biological systems.
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Affiliation(s)
- Geoffrey E Hill
- Department of Biological Sciences, 120 W. Samford Avenue, Auburn University, Auburn, AL, 36849, USA
| | - Ryan J Weaver
- Department of Ecology, Evolution, and Organismal Biology, 2200 Osborne Drive, Iowa State University, Ames, IA, USA
| | - Matthew J Powers
- Department of Integrative Biology, 4575 SW Research Way, Oregon State University, Corvallis, OR, 97331, USA
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Toomey MB, Ronald KL. Avian color expression and perception: is there a carotenoid link? J Exp Biol 2021; 224:269205. [PMID: 34142139 DOI: 10.1242/jeb.203844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Carotenoids color many of the red, orange and yellow ornaments of birds and also shape avian vision. The carotenoid-pigmented oil droplets in cone photoreceptors filter incoming light and are predicted to aid in color discrimination. Carotenoid use in both avian coloration and color vision raises an intriguing question: is the evolution of visual signals and signal perception linked through these pigments? Here, we explore the genetic, physiological and functional connections between these traits. Carotenoid color and droplet pigmentation share common mechanisms of metabolic conversion and are both affected by diet and immune system challenges. Yet, the time scale and magnitude of these effects differ greatly between plumage and the visual system. Recent observations suggest a link between retinal carotenoid levels and color discrimination performance, but the mechanisms underlying these associations remain unclear. Therefore, we performed a modeling exercise to ask whether and how changes in droplet carotenoid content could alter the perception of carotenoid-based plumage. This exercise revealed that changing oil droplet carotenoid concentration does not substantially affect the discrimination of carotenoid-based colors, but might change how reliably a receiver can predict the carotenoid content of an ornament. These findings suggest that, if present, a carotenoid link between signal and perception is subtle. Deconstructing this relationship will require a deeper understanding of avian visual perception and the mechanisms of color production. We highlight several areas where we see opportunities to gain new insights, including comparative genomic studies of shared mechanisms of carotenoid processing and alternative approaches to investigating color vision.
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Affiliation(s)
- Matthew B Toomey
- Department of Biological Science, University of Tulsa, 800 S Tucker Dr., Tulsa, OK 74104, USA
| | - Kelly L Ronald
- Department of Biology, Hope College, 35 East 12th Street, Holland, MI 49422, USA
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Sykes BE, Hutton P, McGraw KJ. Sex-specific relationships between urbanization, parasitism, and plumage coloration in house finches. Curr Zool 2020. [DOI: 10.1093/cz/zoaa060] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Historically, studies of condition-dependent signals in animals have been male-centric, but recent work suggests that female ornaments can also communicate individual quality (e.g., disease state, fecundity). There also has been a surge of interest in how urbanization alters signaling traits, but we know little about if and how cities affect signal expression in female animals. We measured carotenoid-based plumage coloration and coccidian (Isospora spp.) parasite burden in desert and city populations of house finches Haemorhous mexicanus to examine links between urbanization, health state, and feather pigmentation in males and females. In earlier work, we showed that male house finches are less colorful and more parasitized in the city, and we again detected such patterns in this study for males; however, urban females were less colorful, but not more parasitized, than rural females. Moreover, contrary to rural populations, we found that urban birds (regardless of sex) with larger patches of carotenoid coloration were also more heavily infected with coccidia. These results show that urban environments can disrupt condition-dependent color expression and highlight the need for more studies on how cities affect disease and signaling traits in both male and female animals.
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Affiliation(s)
- Brooke E Sykes
- School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Pierce Hutton
- School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Kevin J McGraw
- School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
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Arteni AA, LaFountain AM, Alexandre MTA, Fradot M, Mendes-Pinto MM, Sahel JA, Picaud S, Frank HA, Robert B, Pascal AA. Carotenoid composition and conformation in retinal oil droplets of the domestic chicken. PLoS One 2019; 14:e0217418. [PMID: 31150434 PMCID: PMC6544226 DOI: 10.1371/journal.pone.0217418] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Accepted: 05/10/2019] [Indexed: 12/21/2022] Open
Abstract
Carotenoid-containing oil droplets in the avian retina act as cut-off filters to enhance colour discrimination. We report a confocal resonance Raman investigation of the oil droplets of the domestic chicken, Gallus gallus domesticus. We show that all carotenoids present are in a constrained conformation, implying a locus in specific lipid binding sites. In addition, we provide proof of a recent conclusion that all carotenoid-containing droplets contain a mixture of all carotenoids present, rather than only a subset of them-a conclusion that diverges from the previously-held view. Our results have implications for the mechanism(s) giving rise to these carotenoid mixtures in the differently-coloured droplets.
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Affiliation(s)
- Ana-Andreea Arteni
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Amy M. LaFountain
- Department of Chemistry, University of Connecticut, Storrs, Connecticut, United States of America
| | - Maxime T. A. Alexandre
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Mathias Fradot
- Sorbonne University, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Maria M. Mendes-Pinto
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - José-Alain Sahel
- Sorbonne University, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Serge Picaud
- Sorbonne University, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Harry A. Frank
- Department of Chemistry, University of Connecticut, Storrs, Connecticut, United States of America
| | - Bruno Robert
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Andrew A. Pascal
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
- * E-mail:
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Lind O, Henze MJ, Kelber A, Osorio D. Coevolution of coloration and colour vision? Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0338. [PMID: 28533455 DOI: 10.1098/rstb.2016.0338] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2017] [Indexed: 11/12/2022] Open
Abstract
The evolutionary relationship between signals and animal senses has broad significance, with potential consequences for speciation, and for the efficacy and honesty of biological communication. Here we outline current understanding of the diversity of colour vision in two contrasting groups: the phylogenetically conservative birds, and the more variable butterflies. Evidence for coevolution of colour signals and vision exists in both groups, but is limited to observations of phenotypic differences between visual systems, which might be correlated with coloration. Here, to illustrate how one might interpret the evolutionary significance of such differences, we used colour vision modelling based on an avian eye to evaluate the effects of variation in three key characters: photoreceptor spectral sensitivity, oil droplet pigmentation and the proportions of different photoreceptor types. The models predict that physiologically realistic changes in any one character will have little effect, but complementary shifts in all three can substantially affect discriminability of three types of natural spectra. These observations about the adaptive landscape of colour vision may help to explain the general conservatism of photoreceptor spectral sensitivities in birds. This approach can be extended to other types of eye and spectra to inform future work on coevolution of coloration and colour vision.This article is part of the themed issue 'Animal coloration: production, perception, function and application'.
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Affiliation(s)
- Olle Lind
- Department of Philosophy, Cognitive Science, Helgonavägen 3, 22362 Lund, Sweden
| | - Miriam J Henze
- Queensland Brain Institute, University of Queensland, St Lucia, Queensland 4072, Australia
| | - Almut Kelber
- Department of Biology, Lund Vision Group, Lund University, Sölvegatan 35, 22362 Lund, Sweden
| | - Daniel Osorio
- School of Life Sciences, John Maynard Smith Building, University of Sussex, Falmer, BN1 9QG, UK
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Lim HH, Pike TW. Dietary carotenoid availability affects avian color discrimination. Behav Ecol 2016. [DOI: 10.1093/beheco/arw116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Toomey MB, Lind O, Frederiksen R, Curley RW, Riedl KM, Wilby D, Schwartz SJ, Witt CC, Harrison EH, Roberts NW, Vorobyev M, McGraw KJ, Cornwall MC, Kelber A, Corbo JC. Complementary shifts in photoreceptor spectral tuning unlock the full adaptive potential of ultraviolet vision in birds. eLife 2016; 5:e15675. [PMID: 27402384 PMCID: PMC4947394 DOI: 10.7554/elife.15675] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 06/13/2016] [Indexed: 01/01/2023] Open
Abstract
Color vision in birds is mediated by four types of cone photoreceptors whose maximal sensitivities (λmax) are evenly spaced across the light spectrum. In the course of avian evolution, the λmax of the most shortwave-sensitive cone, SWS1, has switched between violet (λmax > 400 nm) and ultraviolet (λmax < 380 nm) multiple times. This shift of the SWS1 opsin is accompanied by a corresponding short-wavelength shift in the spectrally adjacent SWS2 cone. Here, we show that SWS2 cone spectral tuning is mediated by modulating the ratio of two apocarotenoids, galloxanthin and 11’,12’-dihydrogalloxanthin, which act as intracellular spectral filters in this cell type. We propose an enzymatic pathway that mediates the differential production of these apocarotenoids in the avian retina, and we use color vision modeling to demonstrate how correlated evolution of spectral tuning is necessary to achieve even sampling of the light spectrum and thereby maintain near-optimal color discrimination.
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Affiliation(s)
- Matthew B Toomey
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, United States
| | - Olle Lind
- Department of Philosophy, Lund University, Lund, Sweden
| | - Rikard Frederiksen
- Department of Physiology and Biophysics, Boston University, Boston, United States
| | - Robert W Curley
- College of Pharmacy, The Ohio State University, Columbus, United States
| | - Ken M Riedl
- Department of Food Science and Technology, The Ohio State University, Columbus, United States
- Nutrient and Phytochemical Shared Resource of the OSU-Comprehensive Cancer Center, Columbus, United States
| | - David Wilby
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Steven J Schwartz
- Department of Food Science and Technology, The Ohio State University, Columbus, United States
| | - Christopher C Witt
- Department of Biology, University of New Mexico, Albuquerque, United States
- Museum of Southwestern Biology, University of New Mexico, Albuquerque, United States
| | - Earl H Harrison
- Department of Human Nutrition, The Ohio State University, Columbus, United States
| | - Nicholas W Roberts
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Misha Vorobyev
- Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
| | - Kevin J McGraw
- School of Life Sciences, Arizona State University, Tempe, United States
| | - M Carter Cornwall
- Department of Physiology and Biophysics, Boston University, Boston, United States
| | - Almut Kelber
- Department of Biology, Lund University, Lund, Sweden
| | - Joseph C Corbo
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, United States
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Effects of carotenoid supplementation and oxidative challenges on physiological parameters and carotenoid-based coloration in an urbanization context. Behav Ecol Sociobiol 2015. [DOI: 10.1007/s00265-015-1908-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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de Busserolles F, Hart NS, Hunt DM, Davies WI, Marshall NJ, Clarke MW, Hahne D, Collin SP. Spectral Tuning in the Eyes of Deep-Sea Lanternfishes (Myctophidae): A Novel Sexually Dimorphic Intra-Ocular Filter. BRAIN, BEHAVIOR AND EVOLUTION 2015; 85:77-93. [DOI: 10.1159/000371652] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 09/15/2014] [Indexed: 11/19/2022]
Abstract
Deep-sea fishes possess several adaptations to facilitate vision where light detection is pushed to its limit. Lanternfishes (Myctophidae), one of the world's most abundant groups of mesopelagic fishes, possess a novel and unique visual specialisation, a sexually dimorphic photostable yellow pigmentation, constituting the first record of a visual sexual dimorphism in any non-primate vertebrate. The topographic distribution of the yellow pigmentation across the retina is species specific, varying in location, shape and size. Spectrophotometric analyses reveal that this new retinal specialisation differs between species in terms of composition and acts as a filter, absorbing maximally between 356 and 443 nm. Microspectrophotometry and molecular analyses indicate that the species containing this pigmentation also possess at least 2 spectrally distinct rod visual pigments as a result of a duplication of the Rh1 opsin gene. After modelling the effect of the yellow pigmentation on photoreceptor spectral sensitivity, we suggest that this unique specialisation acts as a filter to enhance contrast, thereby improving the detection of bioluminescent emissions and possibly fluorescence in the extreme environment of the deep sea. The fact that this yellow pigmentation is species specific, sexually dimorphic and isolated within specific parts of the retina indicates an evolutionary pressure to visualise prey/predators/mates in a particular part of each species' visual field.
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Friedman NR, McGraw KJ, Omland KE. History and mechanisms of carotenoid plumage evolution in the New World orioles ( Icterus ). Comp Biochem Physiol B Biochem Mol Biol 2014; 172-173:1-8. [DOI: 10.1016/j.cbpb.2014.03.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 03/18/2014] [Accepted: 03/27/2014] [Indexed: 10/25/2022]
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McCartney KL, Ligon RA, Butler MW, Denardo DF, McGraw KJ. The effect of carotenoid supplementation on immune system development in juvenile male veiled chameleons (Chamaeleo calyptratus). Front Zool 2014; 11:26. [PMID: 24655326 PMCID: PMC4022081 DOI: 10.1186/1742-9994-11-26] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 03/07/2014] [Indexed: 12/04/2022] Open
Abstract
Introduction Nutrient availability, assimilation, and allocation can have important and lasting effects on the immune system development of growing animals. Though carotenoid pigments have immunostimulatory properties in many animals, relatively little is known regarding how they influence the immune system during development. Moreover, studies linking carotenoids to health at any life stage have largely been restricted to birds and mammals. We investigated the effects of carotenoid supplementation on multiple aspects of immunity in juvenile veiled chameleons (Chamaeleo calyptratus). We supplemented half of the chameleons with lutein (a xanthophyll carotenoid) for 14 weeks during development and serially measured multiple aspects of immune function, including: agglutination and lysis performance of plasma, wound healing, and plasma nitric oxide concentrations before and after wounding. Results Though lutein supplementation effectively elevated circulating carotenoid concentrations throughout the developmental period, we found no evidence that carotenoid repletion enhanced immune function at any point. However, agglutination and lysis scores increased, while baseline nitric oxide levels decreased, as chameleons aged. Conclusions Taken together, our results indicate that body mass and age, but not carotenoid access, may play an important role in immune performance of growing chameleons. Hence, studying well-understood physiological processes in novel taxa can provide new perspectives on alternative physiological processes and nutrient function.
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Affiliation(s)
| | - Russell A Ligon
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA.
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McGraw KJ, Giraudeau M, Hill GE, Toomey MB, Staley M. Ketocarotenoid circulation, but not retinal carotenoid accumulation, is linked to eye disease status in a wild songbird. Arch Biochem Biophys 2013; 539:156-62. [DOI: 10.1016/j.abb.2013.09.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 09/11/2013] [Accepted: 09/19/2013] [Indexed: 11/30/2022]
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Ronald KL, Fernández-Juricic E, Lucas JR. Taking the sensory approach: how individual differences in sensory perception can influence mate choice. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2012.09.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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15
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Polo-Cavia N, López P, Martín J. Head coloration reflects health state in the red-eared slider Trachemys scripta elegans. Behav Ecol Sociobiol 2012. [DOI: 10.1007/s00265-012-1435-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Carotenoids in bird testes: links to body carotenoid supplies, plumage coloration, body mass and testes mass in house finches (Carpodacus mexicanus). Comp Biochem Physiol B Biochem Mol Biol 2012; 163:285-91. [PMID: 22771377 DOI: 10.1016/j.cbpb.2012.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 06/26/2012] [Accepted: 06/28/2012] [Indexed: 11/20/2022]
Abstract
Carotenoid pigments can be allocated to different parts of the body to serve specific functions. In contrast to other body tissues, studies of carotenoid resources in the testes of animals are relatively scarce. We used high-performance liquid chromatography to determine the types and concentrations of carotenoids in the testes of house finches (Carpodacus mexicanus). Additionally, we examined the relationships between testes carotenoid concentrations and carotenoid pools in other body tissues, as well as body mass, testes mass and plumage coloration. We detected low concentrations of several carotenoids - lutein (the predominant carotenoid), zeaxanthin, anhydrolutein, β-cryptoxanthin, β-carotene and an unknown carotene - in the testes of wild house finches. We also found that testes lutein levels were significantly and positively associated with circulating lutein levels, while the concentration of zeaxanthin in testes was positively associated with zeaxanthin levels in liver, though in this instance the relationship was much weaker and only marginally significant. Furthermore, lutein levels in testes were significantly negatively associated with testes mass. Finally, plumage coloration was not associated with either the concentration of carotenoids in the testes or relative testes mass. These results suggest that testes carotenoids are reflective of the pool of circulating carotenoids in house finches, and that plumage coloration is unlikely to signal either the carotenoid content of testes tissue or a male's capacity for sperm production.
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Toomey MB, McGraw KJ. Mate choice for a male carotenoid-based ornament is linked to female dietary carotenoid intake and accumulation. BMC Evol Biol 2012; 12:3. [PMID: 22233462 PMCID: PMC3315416 DOI: 10.1186/1471-2148-12-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2011] [Accepted: 01/10/2012] [Indexed: 11/17/2022] Open
Abstract
Background The coevolution of male traits and female mate preferences has led to the elaboration and diversification of sexually selected traits; however the mechanisms that mediate trait-preference coevolution are largely unknown. Carotenoid acquisition and accumulation are key determinants of the expression of male sexually selected carotenoid-based coloration and a primary mechanism maintaining the honest information content of these signals. Carotenoids also influence female health and reproduction in ways that may alter the costs and benefits of mate choice behaviours and thus provide a potential biochemical link between the expression of male traits and female preferences. To test this hypothesis, we manipulated the dietary carotenoid levels of captive female house finches (Carpodacus mexicanus) and assessed their mate choice behavior in response to color-manipulated male finches. Results Females preferred to associate with red males, but carotenoid supplementation did not influence the direction or strength of this preference. Females receiving a low-carotenoid diet were less responsive to males in general, and discrimination among the colorful males was positively linked to female plasma carotenoid levels at the beginning of the study when the diet of all birds was carotenoid-limited. Conclusions Although female preference for red males was not influenced by carotenoid intake, changes in mating responsiveness and discrimination linked to female carotenoid status may alter how this preference is translated into choice. The reddest males, with the most carotenoid rich plumage, tend to pair early in the breeding season. If carotenoid-related variations in female choice behaviour shift the timing of pairing, then they have the potential to promote assortative mating by carotenoid status and drive the evolution of carotenoid-based male plumage coloration.
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Affiliation(s)
- Matthew B Toomey
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA.
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18
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Absorbance of retinal oil droplets of the budgerigar: sex, spatial and plumage morph-related variation. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2011; 198:43-51. [DOI: 10.1007/s00359-011-0684-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2011] [Accepted: 09/14/2011] [Indexed: 10/17/2022]
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Fuller RC, Claricoates KM. Rapid light-induced shifts in opsin expression: finding new opsins, discerning mechanisms of change, and implications for visual sensitivity. Mol Ecol 2011; 20:3321-35. [PMID: 21749514 DOI: 10.1111/j.1365-294x.2011.05180.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Light-induced shifts in cone frequency and opsin expression occur in many aquatic species. Yet little is known about how quickly animals can alter opsin expression and, thereby, track their visual environments. Similarly, little is known about whether adult animals can alter opsin expression or whether shifts in opsin expression are limited to critical developmental windows. We took adult wild-caught bluefin killifish (Lucania goodei) from three different lighting environments (spring, swamp and variable), placed them under two different lighting treatments (clear vs. tea-stained water) and monitored opsin expression over 4 weeks. We measured opsin expression for five previously described opsins (SWS1, SWS2B, SWS2A, RH2-1 and LWS) as well as RH2-2 which we discovered via 454 sequencing. We used two different metrics of opsin expression. We measured expression of each opsin relative to a housekeeping gene and the proportional expression of each opsin relative to the total pool of opsins. Population and lighting environment had large effects on opsin expression which were present at the earliest time points indicating rapid shifts in expression. The two measures of expression produced radically different patterns. Proportional measures indicated large effects of light on SWS1 expression, whereas relative measures indicated no such effect. Instead, light had large effects on the relative expression of SWS2B, RH2-2, RH2-1 and LWS. We suggest that proportional measures of opsin expression are best for making inferences about colour vision, but that measures relative to a housekeeping gene are better for making conclusions about which opsins are differentially regulated.
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Affiliation(s)
- Rebecca C Fuller
- Department of Animal Biology, School of Integrative Biology, University of Illinois, Champaign, IL 61820, USA.
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Toomey MB, McGraw KJ. The effects of dietary carotenoid supplementation and retinal carotenoid accumulation on vision-mediated foraging in the house finch. PLoS One 2011; 6:e21653. [PMID: 21747917 PMCID: PMC3126843 DOI: 10.1371/journal.pone.0021653] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 06/07/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND For many bird species, vision is the primary sensory modality used to locate and assess food items. The health and spectral sensitivities of the avian visual system are influenced by diet-derived carotenoid pigments that accumulate in the retina. Among wild House Finches (Carpodacus mexicanus), we have found that retinal carotenoid accumulation varies significantly among individuals and is related to dietary carotenoid intake. If diet-induced changes in retinal carotenoid accumulation alter spectral sensitivity, then they have the potential to affect visually mediated foraging performance. METHODOLOGY/PRINCIPAL FINDINGS In two experiments, we measured foraging performance of house finches with dietarily manipulated retinal carotenoid levels. We tested each bird's ability to extract visually contrasting food items from a matrix of inedible distracters under high-contrast (full) and dimmer low-contrast (red-filtered) lighting conditions. In experiment one, zeaxanthin-supplemented birds had significantly increased retinal carotenoid levels, but declined in foraging performance in the high-contrast condition relative to astaxanthin-supplemented birds that showed no change in retinal carotenoid accumulation. In experiments one and two combined, we found that retinal carotenoid concentrations predicted relative foraging performance in the low- vs. high-contrast light conditions in a curvilinear pattern. Performance was positively correlated with retinal carotenoid accumulation among birds with low to medium levels of accumulation (∼0.5-1.5 µg/retina), but declined among birds with very high levels (>2.0 µg/retina). CONCLUSION/SIGNIFICANCE Our results suggest that carotenoid-mediated spectral filtering enhances color discrimination, but that this improvement is traded off against a reduction in sensitivity that can compromise visual discrimination. Thus, retinal carotenoid levels may be optimized to meet the visual demands of specific behavioral tasks and light environments.
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Affiliation(s)
- Matthew B Toomey
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America.
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MCGRAW KEVINJ, NOLAN PAULM, CRINO ONDIL. Carotenoids bolster immunity during moult in a wild songbird with sexually selected plumage coloration. Biol J Linn Soc Lond 2011. [DOI: 10.1111/j.1095-8312.2010.01594.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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The effects of dietary carotenoid intake on carotenoid accumulation in the retina of a wild bird, the house finch (Carpodacus mexicanus). Arch Biochem Biophys 2010; 504:161-8. [DOI: 10.1016/j.abb.2010.06.033] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 06/17/2010] [Accepted: 06/28/2010] [Indexed: 11/19/2022]
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Butler MW, Toomey MB, McGraw KJ. How many color metrics do we need? Evaluating how different color-scoring procedures explain carotenoid pigment content in avian bare-part and plumage ornaments. Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-010-1074-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Reeves MK, Jensen P, Dolph CL, Holyoak M, Trust KA. Multiple stressors and the cause of amphibian abnormalities. ECOL MONOGR 2010. [DOI: 10.1890/09-0879.1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Toomey MB, Butler MW, McGraw KJ. Immune-system activation depletes retinal carotenoids in house finches (Carpodacus mexicanus). J Exp Biol 2010; 213:1709-16. [DOI: 10.1242/jeb.041004] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
SUMMARY
The costs of developing, maintaining, and activating the immune system have been cited as an important force shaping life-history evolution in animals. Immunological defenses require energy, nutrients and time that might otherwise be devoted to other life-history traits like sexual displays or reproduction. Carotenoid pigments in animals provide a unique opportunity to track the costs of immune activation, because they are diet-derived, modulate the immune system, and are used to develop colorful signals of quality. Carotenoids also accumulate in the retinas of birds, where they tune spectral sensitivity and provide photoprotection. If carotenoid accumulation in the retina follows the patterns of other tissues, then immune activation may deplete retinal carotenoid levels and impact visual health and function. To test this hypothesis, we challenged molting wild-caught captive house finches (Carpodacus mexicanus) with weekly injections of lipopolysaccharide (LPS) and phytohaemagglutinin (PHA) over the course of 8 weeks. Immunostimulated adult males and females produced significant antibody responses and molted more slowly than uninjected control birds. After 8 weeks, immune-challenged birds had significantly lower levels of specific retinal carotenoid types (galloxanthin and zeaxanthin), but there were no significant differences in the plasma, liver or feather carotenoid levels between the treatment groups. These results indicate that immune-system activation can specifically deplete retinal carotenoids, which may compromise visual health and performance and represent an additional somatic and behavioral cost of immunity.
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Affiliation(s)
- Matthew B. Toomey
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
| | - Michael W. Butler
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
| | - Kevin J. McGraw
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
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McGraw K, Toomey M. Carotenoid Accumulation in the Tissues of Zebra Finches: Predictors of Integumentary Pigmentation and Implications for Carotenoid Allocation Strategies. Physiol Biochem Zool 2010; 83:97-109. [DOI: 10.1086/648396] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Knott B, Berg ML, Morgan ER, Buchanan KL, Bowmaker JK, Bennett ATD. Avian retinal oil droplets: dietary manipulation of colour vision? Proc Biol Sci 2009; 277:953-62. [PMID: 19939843 DOI: 10.1098/rspb.2009.1805] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Avian vision is highly developed, with bird retinas containing rod and double-cone photoreceptors, plus four classes of single cones subserving tetrachromatic colour vision. Cones contain an oil droplet, rich in carotenoid pigments (except VS/ultraviolet-sensitive cones), that acts as a filter, substantially modifying light detected by the photoreceptor. Using dietary manipulations, we tested the effects of carotenoid availability on oil droplet absorbance properties in two species: Platycercus elegans and Taeniopygia guttata. Using microspectrophotometry, we determined whether manipulations affected oil droplet carotenoid concentration and whether changes would alter colour discrimination ability. In both species, increases in carotenoid concentration were found in carotenoid-supplemented birds, but only in the double cones. Magnitudes of effects of manipulations were often dependent on retinal location. The study provides, to our knowledge, the first experimental evidence of dietary intake over a short time period affecting carotenoid concentration of retinal oil droplets. Moreover, the allocation of carotenoids to the retina by both species is such that the change potentially preserves the spectral tuning of colour vision. Our study generates new insights into retinal regulation of carotenoid concentration of oil droplets, an area about which very little is known, with implications for our understanding of trade-offs in carotenoid allocation in birds.
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Affiliation(s)
- Ben Knott
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK.
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Affiliation(s)
- Lorenzo Pérez-Rodríguez
- Instituto de Investigación en Recursos Cinegéticos, IREC (CSIC, UCLM, JCCM), Ciudad Real, Spain.
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