Meeting Abstract

S2.3-3  Saturday, Jan. 4 14:30  Cellular respiration: the nexus of stress, condition, and ornamentation HILL, G. E.; Auburn Univ. ghill@acesag.auburn.edu

Current theory suggests that females benefit by choosing highly ornamented males as mates because ornamentation is an honest signal of male condition. Empirical studies on a diversity of vertebrates and invertebrates have demonstrated associations between ornamentation and a host of parameters associated with condition including adiposity, immunocompetence, oxidative state, neuromuscular function, and cognition. From this literature, there appears to be no core aspect of system function revealed by ornamentation. Here I propose that the primary determinant of individual condition is cellular respiration and in particular oxidative phosphorylation (OXPHOS). Dysfunction of OXPHOS leads to reduced production of ATP and oxidative stress via the release of free radicals. Oxidative stress and reduced energy production, in turn, negatively affect ornament production while at the same time inhibiting immune responsiveness, restricting protein production, reducing fat stores, and depressing behavioral activity. Thus, a fundamental link between OXPHOS and ornamentation explains the commonly observed associations between ornamentation, oxidative state, and energy-demanding processes such as immune defense. Environmental stress affects ornamentation largely through negative effects on cellular respiration. Because OXPHOS efficiency lies at the core of system functionality, it is the property that females should assess most closely in prospective mates. I propose that condition-dependent ornaments evolve via female mate choice as uncheatable signals of OXPHOS efficiency. I use carotenoid pigmentation as an example of a condition-dependent trait for which production is intimately linked to OXPHOS through sensitivities to the oxidative state of the mitochondria.