title: Predator: non-predator ratios in beetle assemblages.
abstract: In common with samples from less taxonomically constrained studies, significant correlations exist between the numbers of predatory and non-predatory species in assemblages of terrestrial beetles. Under logarithmic transformation the relationship can be described reasonably well by a straight line. Explanations for predator: non-predator relationships based on the dynamics of trophic interactions (e.g. competition for prey types or enemy-free space) seem insufficient to explain this pattern, because within beetle assemblages the necessary interactions are so few. Of other proposed determinants, those based on the relationship of local and regional species pools, on energetics, or on non-trophic factors seem the most plausible candidates for explaining proportionality amongst beetles. Much of the deviation from the overall pattern can be accounted for by sampling method and latitude. Temperate samples have a higher proportion of predatory species than tropical, whilst litter and pitfall trap samples have higher proportions of predatory species than Malaise trap and fogging samples.
authors.affiliation: Department of Entomology, The Natural History Museum, Cromwell Road, SW7 5BD, London, UK.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Gaston
authors.affiliation: Department of Animal and Plant Sciences, The University of Sheffield, PO Box 601, S10 2UQ, Sheffield, UK.
authors.forename: Philip H
authors.initials: PH
authors.lastname: Warren
authors.affiliation: Department of Entomology, The Natural History Museum, Cromwell Road, SW7 5BD, London, UK.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Hammond
keywords: Coleoptera; Predator-prey ratios; Trophic structure