Korzan, W.J.*; Summers, T.R.; Miner, H.M.; Martin, M.L.; Flynn, M.B.; Summers, C.H.: Manipulating a Visual Signal of Sympathetic Activity: Influences on Social Status and Plasma Catecholamines
Darkening of postorbital skin in Anolis carolinensis occurs during stressful situations, and is stimulated by adrenal catecholamines via BETA2-adrenergic receptors. This eyespot forms more rapidly in dominant males during social interaction. It was hypothesized that eyespot darkening (green to black) is a social signal communicating sympathetic activation and limiting aggressive interaction. To assess the value of the eyespot as a social signal, males paired according to size and weight were painted postorbitally one with green paint and the other with black paint. The pairs interacted and social hierarchy was determined by counting aggressive behaviors such as aggressive displays, approaches, bites and chases. Males with eyespots darkened by black paint were dominant in 100% of interactions. Males with eyespots painted black also exhibited higher plasma epinephrine, norepinephrine and dopamine levels than males with eyespots hidden with green paint and controls. The potency of the eyespot as a social signal serves as a catalyst that stimulates or inhibits the sympathetic nervous system in aggressive interactions between males. Supported by NSF grant OSR-9452894, Sigma Xi grants in aid and NSF EPSCoR graduate fellowship granted to Wayne J. Korzan
