On the fitness functions relating parental care to reproductive value

Abstract

Models of maximization of reproductive value are based on functions relating the intensity of parental care to two main fitness components: current offspring viability and future offspring production. A trade-off between the two components may be highly dependent on the shape of the underlying functions. Most theoretical models of parental care, however, have only presented an intuitive analysis of their properties. We present an analytical study of some properties of the offspring viability curve in birds. Reproductive value may be maximized in a region of the offspring viability curve that is decelerating. However, when future offspring production decreases at an increasing rate with the intensity of parental care, reproductive value may also be maximized in an accelerating portion of the curve. It is shown that the quantitative and qualitative details of parental care models depend to a large extent on the shape of the underlying fitness functions.