Anomalous predictions of ratio-dependent models of predation

A simple model of ratio-dependent predation is developed, and four empirically testable predictions of this model are developed and discussed. One of these predictions is that the predator's death rate and efficiency should not affect the density or dynamics of the prey. This contradicts a wide variety of empirical knowledge. Two types of extension of the simple model are considered. The first is the introduction of handling time, and the other is the introduction of additional prey species. It is shown that previous representations of both of these extensions are inconsistent with the only mechanism that has been shown to generate a ratio-dependent response. Neither of the extensions changes the main anomalous prediction of ratio-dependent models; i.e., that changing the predator's death rate or other components of its fitness will not affect equilibrium prey density.