Life history and the evolution of parental care

Patterns of parental care are strikingly diverse in nature, and parental care is thought to have evolved repeatedly multiple times. Surprisingly, relatively little is known about the most general conditions that lead to the origin of parental care. Here, we use a theoretical approach to explore the basic life-history conditions (i.e., stage-specific mortality and maturation rates, reproductive rates) that are most likely to favor the evolution of some form of parental care from a state of no care. We focus on parental care of eggs and eggs and juveniles and consider varying magnitudes of the benefits of care. Our results suggest that parental care can evolve under a range of life-history conditions, but in general will be most strongly favored when egg death rate in the absence of care is high, juvenile survival in the absence of care is low (for the scenario in which care extends into the juvenile stage), adult death rate is relatively high, egg maturation rate is low, and the duration of the juvenile stage is relatively short. Additionally, parental care has the potential to be favored at a broad range of adult reproductive rates. The relative importance of these life-history conditions in favoring or limiting the evolution of care depends on the magnitude of the benefits of care, the relationship between initial egg allocation and subsequent offspring survival, and whether care extends into the juvenile stage. The results of our model provide a general set of predictions regarding when we would expect parental care to evolve from a state of no care, and in conjunction with other work on the topic, will enhance our understanding of the evolutionary dynamics of parental care and facilitate comparative analyses.