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Friedman NR, Remeš V. Dorsal and Ventral Plumage Coloration Evolve as Distinct Modules with Different Environmental Correlations. Am Nat 2024; 203:528-534. [PMID: 38489773 DOI: 10.1086/728766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2024]
Abstract
AbstractMany animals exhibit contrast between their dorsal coloration and their ventral coloration. If selection acts differently on dorsal versus ventral coloration, ancestral covariance between these traits should break down, eventually leading to independent modules of trait evolution. Here, we compare the evolution of feather color across body regions for a clade of Australasian songbirds (Meliphagoidea). We find evidence for three modules of covarying color regions. Among these modules, ventral feathers evolve with high lability, evolving at three times the rate of dorsal plumage and 20 times the rate of flight feathers. While both dorsal plumage and ventral plumage are darker in areas with more precipitation and vegetation, we find that dorsal plumage is twice as similar to colors in satellite photos of background substrates. Overall, differential selection on ventral and dorsal colors likely maintains these as distinct modules over evolutionary timescales-a novel explanation for dorsoventral contrast in pigmentation.
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2
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Delhey K, Valcu M, Muck C, Dale J, Kempenaers B. Evolutionary predictors of the specific colors of birds. Proc Natl Acad Sci U S A 2023; 120:e2217692120. [PMID: 37579151 PMCID: PMC10450850 DOI: 10.1073/pnas.2217692120] [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: 10/17/2022] [Accepted: 06/23/2023] [Indexed: 08/16/2023] Open
Abstract
Animal coloration is one of the most conspicuous aspects of human-perceived organismal diversity, yet also one of the least understood. In particular, explaining why species have specific colors (e.g., blue vs. red) has proven elusive. Here, we quantify for nearly all bird species, the proportion of the body covered by each of 12 human-visible color categories, and test whether existing theory can predict the direction of color evolution. The most common colors are black, white, gray and brown, while the rarest are green, blue, purple, and red. Males have more blue, purple, red, or black, whereas females have more yellow, brown, or gray. Sexual dichromatism is partly due to sexual selection favoring ornamental colors in males but not in females. However, sexual selection also correlated positively with brown in both sexes. Strong social selection favors red and black, colors used in agonistic signaling, with the strongest effects in females. Reduced predation risk selects against cryptic colors (e.g., brown) and favors specific ornamental colors (e.g., black). Nocturnality is mainly associated with brown. The effects of habitat use support the sensory drive theory for camouflage and signaling. Darker colors are more common in species living in wet and cold climates, matching ecogeographical rules. Our study unambiguously supports existing theories of color evolution across an entire class of vertebrates, but much variation remains unexplained.
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Affiliation(s)
- Kaspar Delhey
- Department of Ornithology, Max Planck Institute for Biological Intelligence, 82319Seewiesen, Germany
| | - Mihai Valcu
- Department of Ornithology, Max Planck Institute for Biological Intelligence, 82319Seewiesen, Germany
| | - Christina Muck
- Department of Ornithology, Max Planck Institute for Biological Intelligence, 82319Seewiesen, Germany
| | - James Dale
- School of Natural Sciences, Massey University, Palmerston North4442, New Zealand
| | - Bart Kempenaers
- Department of Ornithology, Max Planck Institute for Biological Intelligence, 82319Seewiesen, Germany
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3
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Di Giovanni AJ, Villa J, Stanback MT, Thompson CF, Sakaluk SK, Hauber ME, Hanley D. Decision rules for egg-color-based rejection by two cavity-nesting hosts of the brown-headed cowbird. J Exp Biol 2023; 226:jeb245188. [PMID: 37357579 PMCID: PMC10399979 DOI: 10.1242/jeb.245188] [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: 10/13/2022] [Accepted: 06/21/2023] [Indexed: 06/27/2023]
Abstract
Hosts of obligate avian brood parasites often evolve defense mechanisms to avoid rearing unrelated young. One common defense is egg rejection, for which hosts often rely on eggshell color. Most research has assumed that hosts respond to perceived color differences between their own eggs and parasite eggs regardless of the particular color; however, recent experiments have found that many hosts respond more strongly to brown foreign eggs than to equally dissimilar blue eggs. Yet, none of these prior studies tested a brown-egg-laying species and, with only one exception, all were conducted in open nests where light levels are considered sufficient for effective color-based egg discrimination. Here, we explored how two cavity-nesting hosts of the parasitic brown-headed cowbird (Molothrus ater) - the blue-egg-laying eastern bluebird (Sialia sialis) and the brown-egg-laying house wren (Troglodytes aedon) - respond to experimental eggs painted six distinct colors ranging from blue to brown. Rejection responses of both hosts were best predicted by perceived differences in color between the model egg and their own eggs. Specifically, we found that house wrens preferentially rejected eggs bluer than their own eggs. However, although we found that bluebirds relied on perceived differences in color for their egg rejection decisions, further tests are needed to determine whether they preferentially rejected brown eggs or simply responded to absolute perceived differences in color. These findings demonstrate that these cavity-nesting birds treat perceived color differences in distinct ways, which has important implications on the coevolutionary arms races and the interpretation of avian-perceived color differences.
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Affiliation(s)
| | - Juliana Villa
- Department of Biology, George Mason University, Fairfax, VA 22030, USA
| | - Mark T. Stanback
- Department of Biology, Davidson College, Davidson, NC 28035, USA
| | - Charles F. Thompson
- Behavior, Ecology, Evolution, and Conservation Section, School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Scott K. Sakaluk
- Behavior, Ecology, Evolution, and Conservation Section, School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Mark E. Hauber
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Daniel Hanley
- Department of Biology, George Mason University, Fairfax, VA 22030, USA
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4
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Nolazco S, Delhey K, Fan M, Hall ML, Kingma SA, Roast MJ, Teunissen N, Peters A. Which plumage patches provide information about condition and success in a female fairy-wren? Behav Ecol 2022. [DOI: 10.1093/beheco/arac096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Abstract
Recent evidence suggests that female ornaments can commonly act as signals. However, how signaling functions might be affected by the tendency for reduced ornament elaboration in relation to males is less well-understood. We address this in mutually ornamented purple-crowned fairy-wrens. We investigated putatively ornamental (tail, ear coverts, crown) and non-ornamental (throat, back) plumage patches in females and compared our findings to previous studies in males. Both sexes have brown backs, buff-white throats, and turquoise-blue tails (bluer in males), while ear coverts are rufous in females and black in males. Both sexes also have a seasonal crown (slate-gray in females, black-and-purple in males). Dominant (breeder) females expressed more complete and grayer (more ornamented) crowns, although variation in coloration should not be discriminable by individuals. Unexpectedly, subordinates showed more colorful (saturated) rufous ear coverts, which should be discriminable. Condition-dependence was only evident for crown completeness (% slate-gray cover). Females with more reddish-brown backs were more reproductively successful. Variation in plumage characteristics did not explain differential allocation by mates or chances of gaining dominance. Our outcomes were not entirely consistent with findings in males. The most notable disparity was for the crown, a signal used in male-male competition that in females seems to be expressed as an incomplete version of the male crown that is not associated with fitness benefits. Our study shows that in a species, multiple traits can vary in their information content and that female ornaments can sometimes be less informative than in males, even those that are produced seasonally.
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Affiliation(s)
- Sergio Nolazco
- School of Biological Sciences, Monash University , 25 Rainforest Walk, Clayton, Victoria 3800 , Australia
| | - Kaspar Delhey
- School of Biological Sciences, Monash University , 25 Rainforest Walk, Clayton, Victoria 3800 , Australia
- Max Planck Institute for Ornithology , Seewiesen , Germany
| | - Marie Fan
- School of Biological Sciences, Monash University , 25 Rainforest Walk, Clayton, Victoria 3800 , Australia
| | - Michelle L Hall
- Max Planck Institute for Ornithology , Seewiesen , Germany
- School of Biological Sciences, University of Western Australia , 35 Stirling Highway, Perth, Western Australia 6009 , Australia
| | - Sjouke A Kingma
- Max Planck Institute for Ornithology , Seewiesen , Germany
- Behavioural Ecology Group, Department of Animal Sciences, Wageningen University and Research , De Elst 1, 6708 WD Wageningen , The Netherlands
| | - Michael J Roast
- School of Biological Sciences, Monash University , 25 Rainforest Walk, Clayton, Victoria 3800 , Australia
| | - Niki Teunissen
- School of Biological Sciences, Monash University , 25 Rainforest Walk, Clayton, Victoria 3800 , Australia
| | - Anne Peters
- School of Biological Sciences, Monash University , 25 Rainforest Walk, Clayton, Victoria 3800 , Australia
- Max Planck Institute for Ornithology , Seewiesen , Germany
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5
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Roberts SM, Stuart‐Fox D, Medina I. The evolution of conspicuousness in frogs: When to signal toxicity? J Evol Biol 2022; 35:1455-1464. [PMID: 36129907 PMCID: PMC9825868 DOI: 10.1111/jeb.14092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 06/23/2022] [Accepted: 07/19/2022] [Indexed: 01/11/2023]
Abstract
Many organisms use conspicuous colour patterns to advertise their toxicity or unpalatability, a strategy known as aposematism. Despite the recognized benefits of this anti-predator tactic, not all chemically defended species exhibit warning coloration. Here, we use a comparative approach to investigate which factors predict the evolution of conspicuousness in frogs, a group in which conspicuous coloration and toxicity have evolved multiple times. We extracted colour information from dorsal and ventral photos of 594 frog species for which chemical defence information was available. Our results show that chemically defended and diurnal species have higher internal chromatic contrast, both ventrally and dorsally, than chemically undefended and/or nocturnal species. Among species that are chemically defended, conspicuous coloration is more likely to occur if species are diurnal. Our results also suggest that the evolution of conspicuous colour is more likely to occur in chemically defended prey with smaller body size. We discuss potential explanations for this association and suggest that prey profitability (related to body size) could be an important force driving the macroevolution of warning signals.
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Affiliation(s)
| | - Devi Stuart‐Fox
- School of BioSciencesUniversity of MelbourneParkvilleVictoriaAustralia
| | - Iliana Medina
- School of BioSciencesUniversity of MelbourneParkvilleVictoriaAustralia
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7
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Gulizia JP, Downs KM. The Effects of Feed Color on Broiler Performance between Day 1 and 21. Animals (Basel) 2021; 11:1511. [PMID: 34071014 PMCID: PMC8224657 DOI: 10.3390/ani11061511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/12/2021] [Accepted: 05/20/2021] [Indexed: 11/16/2022] Open
Abstract
Two trials were conducted to determine feed color effects on broiler performance. A completely randomized design was used. Trial 1 included four treatments: control (complete broiler starter diet), red, green, and blue; and Trial 2 included four treatments: control, orange, yellow, and purple. Each trial had 4 treatments with 4 replicates (60 birds/treatment) fed to 240 male Cobb 500 broilers during a 21 d grow out. Data were analyzed using the GLM procedure. In Trial 1, there were no treatment effects on average body weight, body weight gain, and feed consumption (p > 0.05). Adjusted feed conversion for control (1.23) was less than red (1.27; p = 0.001) and green (1.26; p = 0.009), with blue (1.25; p = 0.056) tending to be different during the experimental period. In Trial 2, there were no treatment effects on average body weight, feed consumption, and adjusted feed conversion during this study (p > 0.05). Body weight gain between d 1 to 14 for purple (490.78 g/bird) was more than orange (467 g/bird; p = 0.013) and yellow (461 g/bird; p= 0.004), with control (474 g/bird; p = 0.052) tending to be different. Results indicate that these feed colors had some, albeit limited, influence on broiler performance parameters.
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Affiliation(s)
| | - Kevin M. Downs
- School of Agriculture, Middle Tennessee State University, Murfreesboro, TN 37132, USA;
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8
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Fan M, D’alba L, Shawkey MD, Peters A, Delhey K. Multiple components of feather microstructure contribute to structural plumage colour diversity in fairy-wrens. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz114] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
AbstractClosely related species often differ in coloration. Understanding the mechanistic bases of such differences can reveal whether evolutionary changes in colour are driven by single key mechanisms or changes in multiple pathways. Non-iridescent structural plumage colours in birds are a good model in which to test these questions. These colours result from light absorption by pigments, light scattering by the medullary spongy layer (a nanostructure found within barbs) and contributions from other structural elements. Fairy-wrens (Malurus spp.) are a small clade of closely related birds that display a large diversity of ornamental structural colours. Using spectrometry, electron microscopy and Fourier analysis, we show that 30 structural colours, varying from ultraviolet to blue and purple, share a similar barb morphology. Despite this similarity, we find that at the microscopic scale, variation across multiple structural elements, including the size and density of the keratin cortex, spongy layer and melanin, explains colour diversity. These independent axes of morphological variation together account for sizeable amounts of structural colour variability (R2 = 0.21–0.65). The coexistence of many independent, evolutionarily labile mechanisms that generate colour variation suggests that the diversity of structural colours in this clade could be mediated by many independent genetic and environmental factors.
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Affiliation(s)
- Marie Fan
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Liliana D’alba
- Evolution and Optics of Nanostructures Group, Department of Biology, University of Ghent, Ghent, Belgium
| | - Matthew D Shawkey
- Evolution and Optics of Nanostructures Group, Department of Biology, University of Ghent, Ghent, Belgium
| | - Anne Peters
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Kaspar Delhey
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
- Max Planck Institute for Ornithology, Vogelwarte Radolfzell, Radolfzell, Germany
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9
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Cain KE, Hall ML, Medina I, Leitao AV, Delhey K, Brouwer L, Peters A, Pruett-Jones S, Webster MS, Langmore NE, Mulder RA. Conspicuous Plumage Does Not Increase Predation Risk: A Continent-Wide Test Using Model Songbirds. Am Nat 2019; 193:359-372. [PMID: 30794446 DOI: 10.1086/701632] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The forces shaping female plumage color have long been debated but remain unresolved. Females may benefit from conspicuous colors but are also expected to suffer costs. Predation is one potential cost, but few studies have explicitly investigated the relationship between predation risk and coloration. The fairy-wrens show pronounced variation in female coloration and reside in a wide variety of habitats across Australasia. Species with more conspicuous females are found in denser habitats, suggesting that conspicuousness in open habitat increases vulnerability to predators. To test this, we measured attack rates on 3-D-printed models mimicking conspicuously colored males and females and dull females in eight different fairy-wren habitats across Australia. Attack rates were higher in open habitats and at higher latitudes. Contrary to our predictions, dull female models were attacked at similar rates to the conspicuous models. Further, the probability of attack in open habitats increased more for both types of female models than for the conspicuous male model. Across models, the degree of contrast (chromatic and achromatic) to environmental backgrounds was unrelated to predation rate. These findings do not support the long-standing hypothesis that conspicuous plumage, in isolation, is costly due to increased attraction of predators. Our results indicate that conspicuousness interacts with other factors in driving the evolution of plumage coloration.
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10
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Delhey K, Szecsenyi B, Nakagawa S, Peters A. Conspicuous plumage colours are highly variable. Proc Biol Sci 2018; 284:rspb.2016.2593. [PMID: 28100823 DOI: 10.1098/rspb.2016.2593] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 12/13/2016] [Indexed: 11/12/2022] Open
Abstract
Elaborate ornamental traits are often under directional selection for greater elaboration, which in theory should deplete underlying genetic variation. Despite this, many ornamental traits appear to remain highly variable and how this essential variation is maintained is a key question in evolutionary biology. One way to address this question is to compare differences in intraspecific variability across different types of traits to determine whether high levels of variation are associated with specific trait characteristics. Here we assess intraspecific variation in more than 100 plumage colours across 55 bird species to test whether colour variability is linked to their level of elaboration (indicated by degree of sexual dichromatism and conspicuousness) or their condition dependence (indicated by mechanism of colour production). Conspicuous colours had the highest levels of variation and conspicuousness was the strongest predictor of variability, with high explanatory power. After accounting for this, there were no significant effects of sexual dichromatism or mechanisms of colour production. Conspicuous colours may entail higher production costs or may be more sensitive to disruptions during production. Alternatively, high variability could also be related to increased perceptual difficulties inherent to discriminating highly elaborate colours. Such psychophysical effects may constrain the exaggeration of animal colours.
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Affiliation(s)
- Kaspar Delhey
- School of Biological Sciences, Monash University, 3800, Melbourne, Victoria, Australia .,Max Planck Institute for Ornithology, Vogelwarte Radolfzell, 78315 Radolfzell, Germany
| | - Beatrice Szecsenyi
- School of Biological Sciences, Monash University, 3800, Melbourne, Victoria, Australia
| | - Shinichi Nakagawa
- Evolution and Ecology Research Centre and School of Biology, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Anne Peters
- School of Biological Sciences, Monash University, 3800, Melbourne, Victoria, Australia.,Max Planck Institute for Ornithology, Vogelwarte Radolfzell, 78315 Radolfzell, Germany
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11
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Fan M, Hall ML, Kingma SA, Mandeltort LM, Hidalgo Aranzamendi N, Delhey K, Peters A. No fitness benefits of early molt in a fairy-wren: relaxed sexual selection under genetic monogamy? Behav Ecol 2017. [DOI: 10.1093/beheco/arx065] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- Marie Fan
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, Victoria 3800, Australia,
| | - Michelle L Hall
- School of BioSciences, University of Melbourne, Melbourne, Parkville, Victoria 3010, Australia,
- Max Planck Institute for Ornithology, Vogelwarte Radolfzell, Schlossallee 2, D-78315 Radolfzell, Germany, and
| | - Sjouke A Kingma
- Max Planck Institute for Ornithology, Vogelwarte Radolfzell, Schlossallee 2, D-78315 Radolfzell, Germany, and
- Behavioural and Physiological Ecology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, PO Box 11103, 9700CC Groningen, The Netherlands
| | - Lisa M Mandeltort
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, Victoria 3800, Australia,
| | - Nataly Hidalgo Aranzamendi
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, Victoria 3800, Australia,
| | - Kaspar Delhey
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, Victoria 3800, Australia,
- Max Planck Institute for Ornithology, Vogelwarte Radolfzell, Schlossallee 2, D-78315 Radolfzell, Germany, and
| | - Anne Peters
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, Victoria 3800, Australia,
- Max Planck Institute for Ornithology, Vogelwarte Radolfzell, Schlossallee 2, D-78315 Radolfzell, Germany, and
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12
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Medina I, Delhey K, Peters A, Cain KE, Hall ML, Mulder RA, Langmore NE. Habitat structure is linked to the evolution of plumage colour in female, but not male, fairy-wrens. BMC Evol Biol 2017; 17:35. [PMID: 28125973 PMCID: PMC5270345 DOI: 10.1186/s12862-016-0861-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 12/21/2016] [Indexed: 11/10/2022] Open
Abstract
Background Both natural and sexual selection may drive the evolution of plumage colouration in birds. This can lead to great variation in plumage not only across species, but also between sexes within species. Australasian fairy-wrens are famous for their brightly coloured males, which exhibit colours ranging from bright blue to red and black. Female plumage in fairy wrens (and in general) has been rarely studied, but it can also be highly variable, including both bright and cryptic plumages. We use a comparative framework to explore the basis for this variation, and test the possibility that female fairy-wrens experience selection for cryptic plumage when they occupy more exposed habitats that offer little concealment from predators. We use spectral measurements of plumage for species and subspecies of Australasian fairy-wrens. Results We show that female colouration (contrast against background) is strongly correlated with vegetation cover: females in open habitats show less contrast to background colours than females in closed habitats, while male colouration is not associated with habitat type. Conclusions Female plumage appears to be under stronger natural selection than male plumage in fairy-wrens, providing an example of how selection may act differently on males and females of the same species. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0861-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Iliana Medina
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, 0200, Australia.
| | - Kaspar Delhey
- School of Biological Sciences, Monash University, Melbourne, Australia.,Max Planck Institute for Ornithology, Radolfzell, Germany
| | - Anne Peters
- School of Biological Sciences, Monash University, Melbourne, Australia.,Max Planck Institute for Ornithology, Radolfzell, Germany
| | - Kristal E Cain
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, 0200, Australia.,School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Michelle L Hall
- School of BioSciences, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Raoul A Mulder
- School of BioSciences, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Naomi E Langmore
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, 0200, Australia
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13
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Delhey K. The colour of an avifauna: A quantitative analysis of the colour of Australian birds. Sci Rep 2015; 5:18514. [PMID: 26679370 PMCID: PMC4683462 DOI: 10.1038/srep18514] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 11/03/2015] [Indexed: 12/02/2022] Open
Abstract
Animal coloration is a poorly-understood aspect of phenotypic variability. Here I expand initial studies of the colour gamut of birds by providing the first quantitative description of the colour variation of an entire avifauna: Australian landbirds (555 species). The colour of Australian birds occupies a small fraction (19%) of the entire possible colour space and colour variation is extremely uneven. Most colours are unsaturated, concentrated in the centre of colour space and based on the deposition of melanins. Other mechanisms of colour production are less common but account for larger portions of colour space and for most saturated colours. Male colours occupy 45–25% more colour space than female colours, indicating that sexual dichromatism translates into a broader range of male colours. Male-exclusive colours are often saturated, at the edge of chromatic space, and have most likely evolved for signalling. While most clades of birds occupy expected or lower-than-expected colour volumes, parrots and cockatoos (Order Psittaciformes) occupy a much larger volume than expected. This uneven distribution of colour variation across mechanisms of colour production, sexes and clades is probably shared by avifaunas in other parts of the world, but this remains to be tested with comparable data.
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Affiliation(s)
- Kaspar Delhey
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia.,Max Planck Institute for Ornithology, Radolfzell, 78315, Germany
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14
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Su S, Lim M, Kunte K. Prey from the eyes of predators: Color discriminability of aposematic and mimetic butterflies from an avian visual perspective. Evolution 2015; 69:2985-94. [PMID: 26477885 DOI: 10.1111/evo.12800] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 09/12/2015] [Accepted: 10/05/2015] [Indexed: 11/29/2022]
Abstract
Predation exerts strong selection on mimetic butterfly wing color patterns, which also serve other functions such as sexual selection. Therefore, specific selection pressures may affect the sexes and signal components differentially. We tested three predictions about the evolution of mimetic resemblance by comparing wing coloration of aposematic butterflies and their Batesian mimics: (a) females gain greater mimetic advantage than males and therefore are better mimics, (b) due to intersexual genetic correlations, sexually monomorphic mimics are better mimics than female-limited mimics, and (c) mimetic resemblance is better on the dorsal wing surface that is visible to predators in flight. Using a physiological model of avian color vision, we quantified mimetic resemblance from predators' perspective, which showed that female butterflies were better mimics than males. Mimetic resemblance in female-limited mimics was comparable to that in sexually monomorphic mimics, suggesting that intersexual genetic correlations did not constrain adaptive response to selection for female-limited mimicry. Mimetic resemblance on the ventral wing surface was better than that on the dorsal wing surface, implying stronger natural and sexual selection on ventral and dorsal surfaces, respectively. These results suggest that mimetic resemblance in butterfly mimicry rings has evolved under various selective pressures acting in a sex- and wing surface-specific manner.
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Affiliation(s)
- Shiyu Su
- National Center for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India. .,Department of Biological Sciences, National University of Singapore, Singapore.
| | - Matthew Lim
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Krushnamegh Kunte
- National Center for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India.
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15
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Pérez i de Lanuza G, Font E. Differences in conspicuousness between alternative color morphs in a polychromatic lizard. Behav Ecol 2015. [DOI: 10.1093/beheco/arv075] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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16
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Lind O, Delhey K. Visual modelling suggests a weak relationship between the evolution of ultraviolet vision and plumage coloration in birds. J Evol Biol 2015; 28:715-22. [DOI: 10.1111/jeb.12595] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 01/25/2015] [Indexed: 12/01/2022]
Affiliation(s)
- O. Lind
- Department of Philosophy; Lund University; Lund Sweden
- Department of Optometry and Vision Science; The University of Auckland; Auckland New Zealand
| | - K. Delhey
- School of Biological Sciences; Monash University; Melbourne Vic. Australia
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17
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Delhey K, Delhey V, Kempenaers B, Peters A. A practical framework to analyze variation in animal colors using visual models. Behav Ecol 2014. [DOI: 10.1093/beheco/aru198] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Camargo MGG, Cazetta E, Morellato LPC, Schaefer HM. Characterizing background heterogeneity in visual communication. Basic Appl Ecol 2014. [DOI: 10.1016/j.baae.2014.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Delhey K, Smith J, Peters A. Colour-variable birds have broader ranges, wider niches and are less likely to be threatened. J Evol Biol 2013; 26:1559-68. [PMID: 23663162 DOI: 10.1111/jeb.12157] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 02/28/2013] [Accepted: 03/15/2013] [Indexed: 11/30/2022]
Abstract
Coloration fulfils a variety of adaptive functions in animals. Colour variability, both between and within species, can be caused by different colours being favoured for different functions and in different environments. Thus, species with highly variable coloration may have greater potential to persist in new and changing environments. As a consequence, such colour-variable species may be more able to adapt, colonize new areas and niches, occupy larger ranges, speciate more readily and in general be less vulnerable to environmental change and extinction. These predictions have been supported by comparative analyses on amphibians and reptiles. However, as coloration in ectotherms plays a key role in thermoregulation, it is unclear whether these results can be generalized to endotherms, such as birds and mammals. Here, we test the hypothesis that more colour-variable endotherms occupy larger ranges/niches and are less vulnerable to the threat of extinction by focussing on colour variation in Australian parrots and passerine birds. As predicted, colour variability was correlated with range size (parrots and passerines) and niche breadth (dietary heterogeneity, parrots only). These relationships support the predicted link between colour variability and adaptability, whereby range size and niche breadth may be a cause of colour variability or vice versa. Irrespective, and as predicted, colour variability was lower in threatened species, even after statistically controlling for other confounding variables. Hence, our study supports the hypothesis that colour-variable species in general are more resilient to environmental change.
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Affiliation(s)
- K Delhey
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia.
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