Environmental Hierarchy, Behavioral Contexts, and Social Evolution in Insects

Social insects are frequently used to investigate the importance of kinship (genetic relatedness) in the evolution of complex societies. These genetic studies often downplay the organizing roles of the environment in shaping the development and expression of socially-relevant traits. As noted by Hamilton (1964) in his original formulation of “genetical” approaches to understanding sociality, the social environment plays a major role in determining phenotypes of social organisms. Each level of biological organization (e.g. genome, cell, individual, social group) has its own environment. At different levels of biological organization, environmental factors (i) act as triggers for developmental processes; and (ii) define natural selective processes. An explicit focus on phenotypes, at different levels of biological organization with different levels of environments, provides a framework to use the evolution of insect sociality as a tool to integrate studies of development and evolution. Special attention is drawn to areas that need further study, especially for tropical species, to complement the wealth of genetic studies and information on temperate species.