The oxidation handicap hypothesis and the carotenoid allocation trade-off |
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Authors: | Alonso-Alvarez C Pérez-Rodríguez L Mateo R Chastel O Viñuela J |
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Institution: | Instituto de Investigación en Recursos Cinegéticos, IREC, CSIC, UCLM, JCCM, Ciudad Real, Spain. carlos.alonso@uclm.es |
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Abstract: | The oxidation handicap hypothesis proposes that testosterone mediates the trade-off between the expression of secondary sexual traits and the fight against free radicals. Coloured traits controlled by testosterone can be produced by carotenoid pigments (yellow-orange-red traits), but carotenoids also help to quench free radicals. Recently, it has been shown that testosterone increases the amount of circulating carotenoids in birds. Here, a testosterone-mediated trade-off in the carotenoid allocation between colour expression and the fight against oxidative stress is proposed. Male red-legged partridges were treated with testosterone, anti-androgens or manipulated as controls. Testosterone-treated males maintained the highest circulating carotenoid levels, but showed the palest red traits and no evidence of oxidative damage. Increased levels of a key intracellular antioxidant (i.e. glutathione) indicated that an oxidative challenge was in fact induced but controlled. The trade-off was apparently solved by reducing redness, allowing increased carotenoid availability, which could have contributed to buffer oxidative stress. |
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Keywords: | antioxidants carotenoids coloured traits glutathione lipid peroxidation oxidative stress physiological trade‐off red‐legged partridges resource allocation testosterone |
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