Colony Life History in the Bumble Bee Bombus terrestris: Interactions, Timing and Control.
The evolutionary success of organisms is dependent on adaptive life histories, but the mechanistic control of life history traits is not often studied from an evolutionary perspective. One fascinating area with the potential to advance the understanding of life history regulation in an evolutionary context is the eusocial insects, since their colonies can themselves be regarded as possessing life histories. This is because whole colonies must develop and reproduce effectively in order to pass on the genes of their members. However, as not all colony members have the same fitness optima for colony life history traits, conflict can exist over the control of these traits. Furthermore, colony traits may respond differently to the external environment than in individual organisms, because affecting the life history of colony members might not have corresponding effects on the life history of whole colonies. In this thesis, I use laboratory experiments with the bumble bee Bombus terrestris to investigate the control of eusocial insect colony life history, with a focus on the interactions that bring about control over timing. Specifically, I reveal queen control over the onset of male production; show that colonies do not differ over colony development in their response to natal or non-natal worker laid eggs; demonstrate that higher temperature increases the productivity, but not longevity, of individuals and colonies; and find that foraging gene expression in queens may be linked to colony establishment. Taken together, these findings advance the understanding of life history and social evolution by illuminating processes at behavioural and molecular levels which regulate colony life history in eusocial insects. Furthermore, I discuss how this research has potential applications for the ecological and commercial management of bumble bees, which are key pollinators of crops and wild flowers.
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