The University of Edinburgh and Department of Zoology, Oxford Unversity, Oxford OX1 3PS, UNITED KINGDOM.
The study of social evolution is concerned with fitness consequences of interactions between individuals. It has proven to be an excellent area for relating theoretical predictions to empirical observations. I develop social evolution theory in several ways. (1) I demonstrate that limited male fecundity and small mating groups can select for extreme fertility insurance, curbing female biased sex allocation under local mate competition, which explains puzzling sex ratios in protozoan blood parasites. (2) I examine the underlying causes of an observed statistical invariant in the relative size at sex change in animals, revealing that it does not imply as much conservation of biology across taxa as previously imagined. (3) I extend recent theory regarding how local competition impedes the evolution of altruism to show that it also promotes the evolution of spite. This allows me to re-interpret several behaviours in terms of spitefulness, and predict where spite will occur in nature. (4) I apply spite theory to the evolution of chemical (bacteriocin) warfare in bacteria, and derive novel predictions for the evolution of virulence caused by bacterial parasites. (5) I formalize a verbal model for the evolution of costly punishment as a mechanism of promoting cooperation, revealing a logical flaw and the true source of its (potential) selective benefit. (6) I develop a multi-locus methodology for arbitrary social interactions, and apply this to a dynamically-sufficient co-evolutionary analysis of cooperation and costly punishment, revealing when punishment is favoured by selection. (7) I apply this methodology to the evolution of mutation robustness for a simple two-locus model with recombination and inbreeding.