The oxidation handicap hypothesis and the carotenoid allocation trade-off

J Evol Biol. 2008 Nov;21(6):1789-97. doi: 10.1111/j.1420-9101.2008.01591.x. Epub 2008 Aug 18.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Androgen Antagonists / pharmacology
  • Androgens / pharmacology
  • Animals
  • Body Weight / drug effects
  • Carotenoids / blood
  • Carotenoids / metabolism*
  • Female
  • Flutamide / pharmacology
  • Galliformes / metabolism
  • Galliformes / physiology*
  • Glutathione / blood
  • Lipid Peroxidation / drug effects
  • Male
  • Oxidation-Reduction* / drug effects
  • Oxidative Stress / physiology
  • Pigmentation / drug effects
  • Pigmentation / physiology*
  • Random Allocation
  • Testosterone / blood
  • Testosterone / pharmacology

Substances

  • Androgen Antagonists
  • Androgens
  • Carotenoids
  • Testosterone
  • Flutamide
  • Glutathione