KORZAN, W.J.*; SUMMERS, T.R.; SUMMERS, C.H.: Live or Reflected Aggression
Comparison of two established ethological paradigms suggest that the type of experimental design can influence the efficacy of social signaling and the vigor of aggressive display. In two experiments display of social aggression was stimulated in Anolis carolinensis either by a reflection in a mirror or a live combatant. Darkening of postorbital skin in A. carolinensis occurs during stressful situations, and is stimulated by adrenal catecholamines via &beta2-adrenergic receptors. This eyespot forms (green to black) more rapidly in dominant males than subordinate males during social interaction and serves as social signal communicating sympathetic activation and limiting aggressive interaction. In experiment one, individual males interacted with a mirror image. For experiment two, paired males matched for size and weight interacted. In both experiments males were painted postorbitally with green or black paint, and aggressive interaction and social dominance was determined by counting behaviors such as displays, approaches, bites and chases. Males perceiving an opponent with eyespots darkened by black paint achieved or behaved subordinate in 100% of interactions. When comparing the two experimental designs, plasma Epi, NE and DA levels were inverse. Paired males that perceived an opponent with eyespots had increased catecholamine levels and males perceiving a reflected opponent with no eyespot also had increased levels. Eyespot presence also has an effect on central monoamines. The results of these two types of experiments suggest that particular behavioral attributes can be focused and enhanced by characteristics of experimental design. Supported by NIH 1 F31 MH64983-01 granted to W.J.K.
