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Alonso-Alvarez C, Fernández-Eslava B, Alonso D, Galicia D, Arizaga J. Bigger or long-winged male common crossbills exhibit redder carotenoid-based plumage coloration. Curr Zool 2022; 69:165-172. [PMID: 37091992 PMCID: PMC10120982 DOI: 10.1093/cz/zoac038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 05/05/2022] [Indexed: 11/15/2022] Open
Abstract
Abstract
Carotenoid-based ornaments are often considered reliable (honest) individual condition signals because their expression implies physiological costs unaffordable for low-quality animals (handicap signals). Recently, it has been suggested that efficient cell respiration is mandatory for producing red ketocarotenoids from dietary yellow carotenoids. This implies that red colorations should be entirely unfalsifiable and independent of expression costs (index signals). In a precedent study, male common crossbills Loxia curvirostra showing a red plumage reported higher apparent survival than those showing yellowish-orange colors. The plumage redness in this species is due to ketocarotenoid accumulation in feathers. Here, we correlated the male plumage redness (a four-level visual score: yellow, patchy, orange and red) and the body morphology in more than 1000 adult crossbills captured in three Iberian localities to infer the mechanisms responsible for color evolution. A principal component analysis summarized morphometry of ten variables (beak, wing, tarsus length, etc.). The overall body size (PC1) and the length of flight feathers regarding body size (PC3) showed significant positive relationships with plumage redness. Plumage redness was barely correlated to bill shape measures suggesting no constraint in acquiring carotenoids from pine cones. However, large body sizes or proportionally long flying feathers could help carotenoid acquisition via social competition or increased foraging ranges. Proportionally longer flight feathers might also be associated with a specific cell respiration profile that would simultaneously favor flying capacities and enzymatic transformations needed for ketocarotenoid synthesis. Such a phenotypic profile would agree with the hypothesis of ketocarotenoid-based colors acting as individual quality index signals.
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Affiliation(s)
- Carlos Alonso-Alvarez
- Ecología Evolutiva, Museo Nacional de Ciencias Naturales (CSIC), Edificio Pinar, Spain
| | - Blanca Fernández-Eslava
- Ecología Evolutiva,Universidad de Navarra. Facultad de Ciencias, C/ Irunlarrea, Pamplona, Navarra, Spain
| | - Daniel Alonso
- Ornitología,Sociedad de Ciencias de Aranzadi, Zorroagagaina, Donostia, San Sebastián, Spain
| | - David Galicia
- Biología Ambiental, Universidad de Navarra, Facultad de Ciencias, C/ Irunlarrea, Pamplona, Navarra, Spain
| | - Juan Arizaga
- Ornitología, Sociedad de Ciencias de Aranzadi, Zorroagagaina, Donostia, San Sebastián, Spain
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