Components of Density-Dependent Population Dynamics: Models and Tests with Drosophila

This study has tested a model of density-dependent population dynamics in food-limited environments. Parameters of the model were estimated using standard regression techniques and observations on viability and female size in eight populations of Drosophila melanogaster. The model was tested by comparing its predictions with observations of female size that had not been utilized in the estimation process. In general there was good agreement between observations and predictions of the mean size of females supplied with differing amounts of food. There were substantial deviations from the predicted and observed variance of female size. This difference may be attributed to certain simplifying assumptions of the model and factors other than food that contribute to mortality in these experimental systems. These results point to additional phenomena, such as tolerance to waste products, which may be important in the density-dependent population dynamics of Drosophila and should be incorporated in models describing this process.