The Territorial Prior Residence Effect in Convict Cichlids (Cichlasoma Nigrofasciatum GÜNther): Temporal Aspects of Establishment and Retention, and Proximate Mechanisms

[In a series of six laboratory experiments, the time course of development, retention function, and some possible proximate mechanisms underlying the territorial prior residence effect (resident dominance advantage over conspecific intruders) were examined using the territorial convict cichlid, Cichlasoma nigrofasciatum Gunther. In each experiment direct encounters took place between a resident and a like-sized conspecific intruder. In Experiments 1 and 2 it was determined that the resident must be sole occupant of an area for somewhere between 24-48 hours before successfully dominating an intruder. Experiment 3 showed that residents removed from their territories after 3 days residence, placed in an extraterritorial tank for 1 or 2 hours, and then replaced in their territories demonstrated significant dominance over intruders after the 1 hour removal but not the 2 hour removal condition. In Experiment 4, the hypothesis that a resident may become dominant in its territory because of habituation of fear responses in it (neophobia) was tested. Residents were given 3 days to acclimate to an area and were then removed to one of three extraterritorial environments that varied in similarity to the home territory. In general, the greater the extraterritorial dissimilarity to the home territory, the greater was the disruption of the prior residence effect after being returned to the home tank. Apparently, the dissimilar extraterritorial environments dishabituated the animals' habituation of fear to the home environment. Experiments 5 and 6 revealed that the presence of the territorial marker (shelter) during a territorial intrusion is neither necessary nor sufficient in producing the prior residence effect. In almost all of the present experiments, as in past ones, where the prior residence effect was shown the resident reliably attacked first. Also, biting first, in general, was a reliable predictor of eventual dominance. Proximate and ultimate mechanismus underlying the occurence of the prior residence effect in the field and in the laboratory are discussed., In a series of six laboratory experiments, the time course of development, retention function, and some possible proximate mechanisms underlying the territorial prior residence effect (resident dominance advantage over conspecific intruders) were examined using the territorial convict cichlid, Cichlasoma nigrofasciatum Gunther. In each experiment direct encounters took place between a resident and a like-sized conspecific intruder. In Experiments 1 and 2 it was determined that the resident must be sole occupant of an area for somewhere between 24-48 hours before successfully dominating an intruder. Experiment 3 showed that residents removed from their territories after 3 days residence, placed in an extraterritorial tank for 1 or 2 hours, and then replaced in their territories demonstrated significant dominance over intruders after the 1 hour removal but not the 2 hour removal condition. In Experiment 4, the hypothesis that a resident may become dominant in its territory because of habituation of fear responses in it (neophobia) was tested. Residents were given 3 days to acclimate to an area and were then removed to one of three extraterritorial environments that varied in similarity to the home territory. In general, the greater the extraterritorial dissimilarity to the home territory, the greater was the disruption of the prior residence effect after being returned to the home tank. Apparently, the dissimilar extraterritorial environments dishabituated the animals' habituation of fear to the home environment. Experiments 5 and 6 revealed that the presence of the territorial marker (shelter) during a territorial intrusion is neither necessary nor sufficient in producing the prior residence effect. In almost all of the present experiments, as in past ones, where the prior residence effect was shown the resident reliably attacked first. Also, biting first, in general, was a reliable predictor of eventual dominance. Proximate and ultimate mechanismus underlying the occurence of the prior residence effect in the field and in the laboratory are discussed.]