SynthesisPloS one2012
What does carotenoid-dependent coloration tell? Plasma carotenoid level signals immunocompetence and oxidative stress state in birds-A meta-analysis.
Synthesis in PloS one, 2012. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 57 papers, 4 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
57 citing papers in PubMed, 4 syntheses or guidelines pooled it, 197 citations in OpenAlex.
- Synthesis of Nature's Extravaganza: An Augmented Meta-Meta-Analysis on (Putative) Sexual Signals.Ecology letters · 2025Pooled it
- Colourful traits in female birds relate to individual condition, reproductive performance and male-mate preferences: a meta-analytic approach.Biology letters · 2021Pooled it
- Structural colours reflect individual quality: a meta-analysis.Biology letters · 2020Pooled it
- Carotenoid metabolism strengthens the link between feather coloration and individual quality.Nature communications · 2018Pooled it
- Carotenoid-based ornaments predict survival in male but not female birds: A meta-analysis.iScience · 2026Article
- Evidence for the evolution of male and female cardinals' plumage colouration being affected by both natural and sexual selection.BMC ecology and evolution · 2025Article
- Female Starlings With Experimentally Impaired Pre-Laying Condition Produce Smaller But Vitamin A Richer Eggs.Journal of experimental zoology. Part A, Ecological and integrative physiology · 2025Article
- Bdh1l Gene Expression Is a Potential Molecular Factor in the Evolution of Carotenoid-Based Colour Diversity of Cichlid Fishes.Molecular ecology · 2025Article
- The Impairment of Body Condition Transiently Increases Oxidative Stress: A Dietary Restriction Experiment in Partridges.Journal of experimental zoology. Part A, Ecological and integrative physiology · 2025Article
- Reliability of meta-analyses in ecology and evolution: (mostly) good news from a case study on sexual signals.Proceedings. Biological sciences · 2025Article
- Assessment of Oxidative Stress and Associated Biomarkers in Wild Avian Species.Animals : an open access journal from MDPI · 2025Review
- Phylogenetic Relationships of Immune Function and Oxidative Physiology With Sexual Selection and Parental Effort in Male and Female Birds.Ecology and evolution · 2025Article
- Immune stress and diet influence reproductive fitness in male tuatara (Current zoology · 2024Article
- Colouration matters in dull toads: ultraviolet adornment for ladies and agrochemicals fading effects.Oecologia · 2023Article
- The carotenoid redshift: Physical basis and implications for visual signaling.Ecology and evolution · 2023Article
- Bigger or long-winged male common crossbills exhibit redder carotenoid-based plumage coloration.Current zoology · 2023Article
- Performance, Egg Quality, and Immunity of Laying Hens due to Natural Carotenoid Supplementation: A Meta-Analysis.Food science of animal resources · 2023Article
- Translating conventional wisdom on chicken comb color into automated monitoring of disease-infected chicken using chromaticity-based machine learning models.Frontiers in veterinary science · 2023Article
- Article
- Oxidative physiology is weakly associated with pigmentation in birds.Ecology and evolution · 2022Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
3 authors at 2 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Mechanisms maintaining honesty of sexual signals are far from resolved, limiting our understanding of sexual selection and potential important parts of physiology. Carotenoid pigmented visual signals are among the most extensively studied sexual displays, but evidence regarding hypotheses on how carotenoids ensure signal honesty is mixed. Using a phylogenetically controlled meta-analysis of 357 effect sizes across 88 different species of birds, we tested two prominent hypotheses in the field: that carotenoid-dependent coloration signals i) immunocompetence and/or ii) oxidative stress state. Separate meta-analyses were performed for the relationships of trait coloration and circulating carotenoid level with different measures of immunocompetence and oxidative stress state. For immunocompetence we find that carotenoid levels (r = 0.20) and trait color intensity (r = 0.17) are significantly positively related to PHA response. Additionally we find that carotenoids are significantly positively related to antioxidant capacity (r = 0.10), but not significantly related to oxidative damage (r = -0.02). Thus our analyses provide support for both hypotheses, in that at least for some aspects of immunity and oxidative stress state the predicted correlations were found. Furthermore, we tested for differences in effect size between experimental and observational studies; a larger effect in observational studies would indicate that co-variation might not be causal. However, we detected no significant difference, suggesting that the relationships we found are causal. The overall effect sizes we report are modest and we discuss potential factors contributing to this, including differences between species. We suggest complementary mechanisms maintaining honesty rather than the involvement of carotenoids in immune function and oxidative stress and suggest experiments on how to test these.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.