Meeting Abstract
Pace of Life (POL) models have recently emerged to integrate covariation among behavioral, physiological, and life history traits along a single fast-slow axis. Variation in metabolic rate, the fundamental biological rate at which organisms acquire, process, and expend energy, is often considered the primary driver of phenotypic covariation that defines POL at an organismal level. The metabolic theory of ecology however suggests that the functional importance of metabolic rate should also drive similar patterns at higher levels of organization, although such ideas have rarely been empirically investigated. Using honeybees (Apis mellifera) as an experimental model, we measured a number of behavioral, physiological, and life history traits at the individual and group level. We then adopted a structural equation modeling approach to present evidence of a POL in honeybees consistent with many of the theoretical predictions and the role of metabolic rate in shaping covariation structure. In order to explore similar patterns at the group level, we then bred genetic lines of honeybees with slow and fast metabolic rates based on the malate dehydrogenase locus and then created experimental groups that were homogenously slow, fast, intermediate, and heterogeneously mixed groups of slow and fast bees. We then assayed these groups on some of the same behavioral, physiological, and life history traits that were measured at the individual level as well as some additional group level traits, in resource rich and poor environments. Using a partitioning of variance approach on these trait values across different group compositions, we then investigated the relative selection (non-additive) and complementarity (additive) effects of metabolic rate and how they interact with the resource environment in shaping the pace of life at higher levels of biological organization.
