INDIVIDUAL RECOGNITION IN JEWEL FISH (HEMICHROMIS BIMACULATUS): THE ROLE OF FACE RECOGNITION AND VISUAL PATTERN DISCRIMINATION.

摘要

Individual recognition, or the ability to identify a particular animal as unique, is the basis of many important social behaviors, including formation of social hierarchies, imprinting, and mate recognition. Reproductive behavior of jewel fish (Hemichromis bimaculatus) demonstrates the significant ecological role individual recognition plays. Mated jewel fish cooperate in territorial defense against predation of their eggs and fry. Each partner must recognize its mate as the one other fish permitted in its territory.; In humans, face recognition is practically synonymous with individual recognition because our identification process relies heavily upon facial cues. For other animals, isolating cues significant to individual recognition by and of a particular species is critical to understanding how individual recognition functions in that species. Jewel fish have a perceptually salient pattern of shiny blue facial and flank iridophores, and this dissertation investigates the hypothesis that facial iridophore patterns are perceptual cues to individual recognition. Facial models were used to study face recognition, then embellished with iridophore patterns to test for individual recognition. Recognition was measured using indices of both flight response and respiration rate. Because individual recognition is ecologically required of jewel fish only as they mature and their perceptual systems develop, a developmental approach testing fry through sub-adults was adopted. Discrimination between models varying in iridophore pattern was demonstrated with juveniles, but not fry, and discrimination between models with only subtle variation in very realistic iridophore patterns was observed in older sub-adults.; Uniqueness of iridophore pattern would also be necessary for it to be a cue to identify a particular fish as an individual. A pattern analysis of two spawns of jewel fish was therefore undertaken, which confirmed that each jewel fish iridophore pattern is unique and, significantly, that there exists interspawn pattern variation.