Meeting Abstract
A key question in evolutionary biology concerns the mechanisms by which sexual displays serve as uncheatable signals of condition. It has been proposed that the process of metabolizing dietary carotenoids into sexual signals may be the basis for honest signaling for many color displays. Most animal diets contain only yellow carotenoids such as lutein and zeaxanthin. To display red carotenoid coloration, animals must metabolically convert these yellow carotenoids to red. Numerous studies on birds, fish, and reptiles have demonstrated that the hue and saturation of red carotenoid-based color displays is associated with the condition and quality of individuals. We recently proposed that carotenoid-based ornaments are an index signal of mitochondrial performance because the conversion of yellow dietary carotenoids to red carotenoids shares a pathway with redox reactions of mitochondrial respiration. Here we test predictions of this hypothesis by comparing how the effect of hybridization on carotenoid metabolism differs between hybrids of species with either deep or shallow mitochondrial divergence. We find that hybrids show breakdown in carotenoid metabolism when the parental species are deeply diverged, and vigor when parental species are shallowly diverged. We discuss the results in the context of the evolution of honest signaling from carotenoids in animals.
