| Abstract: | In evaluating the role of behavioral interactions in the maintenance of ecological and ethological isolation in sympatric populations of P. leucopus and P. gossypinus, the interspecific behavior of 94 animals in all possible sex pair combinations was observed in 84 staged dyadic trials of 15-minutes duration. Qualitatively the patterns of behavior differed little between sexes or species. Despite a high inter-individual variability and the high proportion of amicable interactions, the mean frequency of occurrence of aggressive behavior as well as the number of trials in which aggressive behavior occurred was greater in trials of animals from areas of range sympatry in comparison with those of the control animals from areas of range allopatry. Although the dominance relationships in many trials were unclear, gossypinus nonetheless consistently dominated leucopus. These data combined with examination of the habitats of these mice where their ranges do not overlap suggest that agonistic interactions may implement species integrity either primarily by Limiting or preventing the occupancy by leucopus of areas in which gossypinus occurs or secondarily by reducing the chances of pair bond formation. |
