The social context of life history evolution

We discuss ways in which the social environment as individual inhabits may have influenced, and continues to influence, the lift history patterns it follows. We argue that the social context in which a life history is expressed has the potential to influence the evolution of that life history in four distinct ways, and that these may not always have been fully considered in classic life history theory. First, conflicts of interest are frequent when non-clonal organisms interact, and this is particularly true for reproduction, where conflicts between the sexes and between parents and offspring have numerous potential impacts on life histories. Second, the occurrence of frequency- and density-dependent selection arising from social interactions can have important consequences for predicting the evolutionary trajectories of life histories. Third, research in sexual selection has often been free of a life-history perspective; combining the two has the potential to offer interesting insights into the process of sexual selection and the evolution of sexual ornamentation. Finally, we illustrate some of the more dramatic outcomes of these factors for life history evolution by discussing the evolution and maintenance of within population polymorphisms in life histories. An appreciation of the roles of social interactions may provide a solution to some long-standing questions in life-history research, such as how high levels of additive genetic variance for traits closely related to fitness are maintained.