| Cooperation is a pervasive feature of life. Highly cooperative species, including eusocial insects and humans, are among the most ecologically dominant organisms on the planet, and cooperation itself is responsible for the evolutionary transitions in organismal complexity that lead to the emergence of genomes, multicellularity and societies. Despite its ubiquity, explaining how cooperation evolves remains a central challenge of evolutionary theory: How can natural selection favor self-sacrificial behavior when selfish conflict arising from within-group advantage constantly threatens to undermine group cohesion? Using mathematical theory, computer simulations, and bioinformatic analysis of gene sequence data, I have investigated the interplay between ecology (e.g., density regulation, heterogeneous environments, resource abundance) and genetics (e.g., population structure, mutation, conditional gene expression) in determining the outcome of the evolutionary tug-of-war between cooperation and conflict. I show how cooperation can evolve in scarce or abundant environments, under high or low dispersal, and despite the recurrent introduction of cheaters via mutation. My work identifies a number of novel phenomena, provides a novel empirical test of social evolution theory using molecular data, and resolves a number of long-standing dilemmas surrounding the origin and maintenance of cooperation in nature. |
