Mate guarding as a key factor in the evolution of parental care in birds

The evolution of male parental care in vertebrates with internal fertilization must have been preceded by a stage in which males profit by staying with the female after copulation. This paper discusses the results of a series of computer simulations to determine the pay-off to post-copulatory mate guarding under various conditions. Guarding is promoted by asynchrony in fertility of the females, high copulation frequencies of females, preference of females for males using the guarding strategy, and mate fidelity of guarded females. Moreover, it is demonstrated that, under several conditions, apparently those operating in a natural environment, the success of the guarding strategy is inversely related to its frequency in the population. This implies that both the guarding and the non-guarding strategy can be maintained in the same population. This phenomenon is put forward as a key factor determining the pathways in the evolution of parental care.