Environmental and genetic components of a major evolutionary transition: social plasticity in halictine bees.

The evolution of sociality is one of the major transitions in evolutionary biology. The key testing ground for theories concerning the origin of helping have been primitively eusocial taxa, in which behaviour is highly plastic. Social phenotype varies within these species, both temporally and spatially, from non-social to fully eusocial. Differences in social phenotype are correlated with factors such as latitude, altitude and habitat features. Yet the extent to which differences are genetically based, or represent condition-sensitive phenotypic expression, is almost unknown. Our research will use a combination of large-scale manipulative field experiments and molecular genetic analyses: (1) To test whether inter-population variation in social phenotype represents genetic differentiation or is a phenotypic response to environmental conditions. (2) To investigate the transition between social phenotypes along an environmental gradient. (3) To quantify the degree of reproductive isolation between the two social forms at a transition zone between them. (4) To test whether social populations form a grouping distinct from non-social populations in an intraspecific phylogeny. The work will involve a collaboration between researchers at University College London and Queen's University Belfast, employing a postdoctoral researcher and a 75% time technician. The study system will be British populations of sweat bees.