Meeting Abstract
Variation in body size, a central theme for integrative organismal biology, influences fitness and shapes ecological and evolutionary interactions. In insects, body size is a product of growth rate and the factors that regulate metamorphic induction late in larval development, such as attainment of a critical weight, a terminal growth period, and growth cessation. However, the generality of these factors/mechanisms for different insect species is an open question. We examined causes of metamorphic induction and consequences on adult size variation in the solitary bee, Osmia lignaria. We found that this species used absence of food provisions as a cue for metamorphosis rather than a critical weight. In addition, excess provisions caused a delay of metamorphosis, suggesting that multiple cues and/or mechanistic interactions regulate metamorphosis in this species. Approximately 90% of body size variation in adults was due to differences in the timing of metamorphic induction. Manipulation of food provisioning induced more than a ten-fold mass difference between the smallest and largest adult bees. When we examined body plan morphologies, we found that allocation to flight structures, but not reproductive structures, was different in small and large bees. These results imply that mechanisms shaping size variation and consequences for individuals are diverse among different insects and reflect the environmental context for each species.
