The Evolution of Social Behaviour Symposium, organized by Graham Thompson (Western), Amro Zayed (York) and Miriam Richards (Brock), was held at CSEE-Kelowna on 14 May 2013. A major theme of the symposium was “sociogenomics”; research designed to uncover genetic mechanisms underlying evolutionary process in social animals, including the development of behavioural differences between queens (breeders) and workers (usually non-breeders) in social Hymenoptera, which are the most widely used models for the study of social evolution.
Sandra Rehan (U. Pennsylvania) presented a network analysis designed to uncover genetic mechanisms of age polyethism in the Pharaoh ant. Alison Camiletti (Western) showed that some social behaviours of honeybees, like the worker ovarian response to queen mandibular pheromone, can be reproduced in completely unrelated insects like fruit flies, emphasizing that highly derived phenotypes often “re-use” ancient genetic networks. Tim Linksvayer (U. Pennsylvania) extended the concepts of behavioural genomics even further to propose that behavioural genes influence not only the behavioural phenotypes of the individuals that carry them, but also the phenotypes of individuals with which they interact – ‘extended genotypes’, if you will. Clement Kent (York) turned these concepts around; instead of thinking about the influence of genes on social behaviour, he emphasized the effect that sociality can have on the rate and pattern of molecular evolution, producing some distinctly curious traits in honeybee genomes.
Primitively eusocial bees are those in which females are “totipotent”: any newly emerged adult female can adopt any of the major reproductive roles typical of a particular species. For instance, in facultatively social sweat bees, females may become solitary breeders, raising their own brood by themselves, or they can nest socially, behaving as either egg-laying queens or mostly altruistic workers. Karen Kapheim (U. Illinois) showed how a female’s career choices are biased by the way her mother varies the quality of larval provisions, and presented a model demonstrating that eusociality evolves more easily as a result of such maternal manipulation than it does by the better known, potential inclusive fitness payoffs to worker altruism. Sarah Kocher (Harvard) presented a novel take on the geographic distribution of sociality in sweat bees. Using a phylogenetic approach, she demonstrated an inverse correlation between altitude and the frequency of eusociality, whereby higher altitudes are associated with breeding seasons shorter than those necessary to accommodate the longer colony cycles of eusocial species.
Several talks reminded us that bees are not (surprisingly) the bee all and all. Tom Chapman (Memorial) used classic approaches including phylogenetics and detailed behavioural observations, to dissect the altruistic behaviour of thrips soldiers. Not only do soldiers aggressively defend their colonies against invasion by other thrips, but they also play a role in defending their colonies against microbial infection. Melissa Holmes (U. Toronto) described how social status influences brain development in naked mole rats, and provided some fascinating parallels between eusocial mammals and insects, as well as some intriguing differences. This was one of those rare occasions in which the entomologists in the room were in the position of owning the “standard” model organisms, but the consensus was that naked mole rats deserved honorary status as fascinating (but ugly) social insects. Finally, two talks championed the theoretical approache to the study of social life. Geoff Wild (Western) reminded us that the study of social evolution is not just about genes, but is inextricably linked to real-life ecology. Geoff focussed on the important role of ecological constraints on independent breeding as a necessary condition for the evolution of social breeding. Jay Biernaskie (Oxford) provided another example of how useful it can be to look at a question from a different angle. Kin selection tends to be used as an explanation of the nicer aspects of social evolution, for example, group-living, cooperation, and altruism. Jay flipped us to the dark side, showing us how kin selection can equally lead to competitiveness, antagonism, and murder in small groups.
The symposium ended with a discussion in which all participants attempted to extract an over-riding theme from the day’s presentations. We couldn’t reach a consensus! But it was clear that the evolutionary study of social behaviour, and the sociogenomic techniques that underpin it, are advancing on more than one front. They are distinct, but are interrelated and mutually informative. One of our objectives in organizing this symposium was to illustrate the breadth of research questions, methods, and study organisms in the field of social evolution, but also to encourage synthesis within the field as a whole. The CSEE was an ideal venue to initiate this synthesis in advance of next year’s World Congress of the International Union for the Study of Social Insects (IUSSI), the pre-eminent forum on social evolution.