Factors influencing prey community structure: the effects of the prey-species selection by the predator Haplotrema concavum and the effects of interspecific interactions between those prey-species.

Abstract

This research project was designed to test two hypotheses: 1) predator preference influences its prey community structure and 2) the interaction between the prey species also influences the prey community structure. The system used in the study was that of the carnivorous land snail Haplotrema concavum and fifteen prey species. Two procedures were used to determine if there was any relationship between H. concavum prey preference and the relative abundance of those prey. The first procedure involved gathering random samples of the prey from a designated site and calculating their relative abundance. The second procedure involved various feeding trials from which a hierarchy of H. concavum prey preference was determined. The relative abundance was correlated between the species and with the preference hierarchy. The results showed that there was no correlation between H. concavum prey preference and the relative abundance of those prey. However, there were significant correlations found between the relative abundance of the prey species. These results suggest that H. concavum predation is not a significant factor in structuring its prey community, whereas species interactions do play a role.