Guild Size in Drosophilids: A Simulation Model

(1) This paper describes a simulation model which predicts the guild size of drosophilid flies living on a divided and ephemeral resource, without any traditional resource partitioning. (2) A distribution of empirical guild sizes was obtained from fifty-three field studies collected from all over the world. The resource bases used by the flies were fruit, fungi, sap fluxes, decaying leaves and flowers. The modal guild size was seven. (3) An acceptable range of parameter values for the model was obtained from a combination of field and laboratory experiments. Within this range the model predicted distributions of guild sizes slightly less than those observed in the field, with a modal size which varied between five and six.