Phylogenetical Constraints in the Evolution of Parental Care Strategies in Birds

Abstract

In species with internal fertilization, but without parental care, an evolution of 'maternal care' is fundamentally different from an evolution of 'paternal care'. Maternal care should be a pure EES. Paternal care should always be superimposed on a mixed ESS to stay (or not to stay) and to establish some kind of a pair-bond with the female from copulation until egg-laying. This implies that paternal care is less reliable than maternal care. This could have led to the evolution of female strategies and properties which raise the chances for male care. The above considerations offer a framework for the evolutionary pathways between the various parental care strategies and between their associated mating systems. Both paternal and maternal care might directly evolve towards biparental care. For the evolution from paternal towards biparental care it is more likely, however, that a transitional stage of 'uniparental care' will be passed. That stage is characterized by paternal care in most cases, but by maternal care if the male deserts. It is probable that the biparental care system with similar roles for both sexes evolved along this route. Since such similar role systems are widely distributed among birds, and since monogamous paternal care systems can easily evolve towards all recent mating systems in birds, it is advocated that the evolution of parental care in birds was primarily based on a monogamous paternal care system.