Resource partitioning and interspecific competition in a tropical hermit crab community

1) The relative intensities of inter- and intra-specific competition for a given set of resources can be estimated from data on resource partitioning if enough is known about resource population dynamics and resource movement. 2) There is abundant evidence that hermit crabs compete for empty gastropod shells. Different hermit crab species usually differ in their use of empty shells and habitat. 3) A model of empty shell population dynamics is developed to allow competition ratios to be calculated from data on resource partitioning among sympatric hermit crabs. 4) Ratios of inter- and intra-specific competition are estimated for the species in a tropical hermit crab community. Results indicate that interspecific competition is at least an order of magnitude less than intraspecific. Species are not close to any limiting similarity. 5) The fact that competition ratios in the Panamanian hermit crab community are substantially less than figures proposed by other authors for other communities may reflect the use of inappropriate methods for determining competition coefficients (competition ratios) in earlier studies.