The Role of Time and Energy in Food Preference

A model which relates optimal food preference relationships and caloric yield per unit time of potential food sources is derived. It is suggested, on the basis of this model, that: 1) Food preferences can be adequately described only if a number of factors other than relative frequencies in the diet and relative abundances of the food types are known. 2) Animals should be more selective in their choice of foods when satiated or when food is common, more indiscriminate when starved or when food is scarce. 3) Animals may eat one food type with greater frequency, relative to its abundance, than another even if the other food is richer and more efficiently exploited. This occurs in situations of high relative abundance of the first food type. 4) The extent to which predators tend to pass by potential food items may be used to evaluate the role of food in the population limitation of a predator species. 5) Food preferences appear to change readily and appropriately to changes in the environment. preferences a stable equilibrium tends to become established. The terms pegmatype and pegmatypic mating are introduced to describe such mating preferences and such a mating system.