A quantitative analysis of social interaction of the guppy, Poecilia reticulata (pisces: Poeciliidae) as a function of population density

Abstract

Various controlled densities of guppies, Poecilia reticulata, wer observed in order to determine the effects of population density on frequency of courtship and agonistic interactions. Populations with single male exhibit a low level of courtship activity; the presence of a second male increases this level of activity markedly. Populations with a 1:1 sex ratio in densities greater than one pair exhibit a constant mean number of courtship interactions but, with increased crowding, an increasing variance in level of courtship activity. This results in a frequency profile of courtship interaction characteristic of each observed density. Each population density exhibits a density-dependent pattern of social interaction defined quantitatively by frequencies of courtship aggressive interactions at the population level. The contribution of the behaviour of individual males and to this patterning of social interaction in each population was partially determined.