The role of behavioral polymorphism in the process of intrapopulation segregation of ecological niches in bream, Abramis brama (Cyprinidae)

Abstract

The study of feeding and defensive behavior in the two groups of bream (Abramis brama) differing in the peroxidase locus (presented by Po79 and Po100 alleles) has been performed. The A group bream (homozygous by Po79 allele) exhibit higher locomotor activity and aggressiveness, actively feed in the presence of a predator, and adapt quickly to experimental conditions. The B group bream (homozygous by Po100 allele) exhibit lesser locomotor activity and practical absence of aggressiveness. These fish reject food in the presence of a predator, their behavioral characteristics after removal of the predator recover after a long time and they adapt to experimental conditions slowly. Thus, the study revealed that there really exists the intraspecies form of bream that is less reactive but more aggressive and agile in which conditioning responses develop better. Presence in a population of reactive and nonreactive specimens serves as a basis for the mechanism of regulation of acuteness of intrapopulation relations and range expansion. In the present case, this mechanism allows for the efficient use of alternative resources having inconstant availability.