Multiple patterns of parental care

Many animals show multiple patterns of parental care, where more than one o f the four basic patterns (biparental care, uniparental care by males or fe males, or no care) is present within a single population during a single br eeding season. We consider three reasons for the existence of multiple patt erns of parental care: (1) mixed-strategy behaviours; (2) time-dependent be haviour with parents changing their care decision during the breeding seaso n; and (3) quality differences between individuals leading to different car e decisions being made depending on the qualities of both parents. The basi c framework we use to investigate these is a two-stage game-theoretical mod el, and we highlight the importance of including feedback between the paren tal care decisions made by population members and the probability that a de serting individual will find a new mate. Including this feedback may introd uce a nonlinear dependence of the fitness payoffs on the frequencies with w hich the pure strategies ('care' and 'desert') are played by each of the se xes. This can have important consequences for the existence of evolutionari ly stable strategies (ESSs). For example, mixed-strategy ESSs may exist tan outcome forbidden if the feedback is not included), and, in one model, the feedback also prevents uniparental care by either sex from being evolution arily stable. We also point out that decisions made by animals without depe ndent offspring can have important consequences for observed parental care behaviour. (C) 1999 The Association for the Study of Animal Behaviour.