SIEG, Annette*; O’CONNOR, Michael; Drexel University; Drexel University: Exploring the Possible Radiative Origins of Interspecific Metabolic Allometries

The correlation between body size and a large suite of organismal characteristics has been a subject of much interest in the biological community; and, recently, the scaling of metabolic rate with body size has received renewed attention. The nearly ubiquitous pattern of metabolic allometry in extant organisms lacks a clear general mechanism or set of mechanisms. We examine the potential origin/modification of metabolic allometry via a simulated radiation of competing vertebrate taxa each with life history traits determined by a given allometric exponent. In our simplified model, we examine the outcomes of competition of individual organisms in a bounded homogenous environment with their daily activity, resource allocation rules and aging based on a selected set of metabolic allometries. The simulation consists of carnivorous and herbivorous animals that exhibit predator-prey relationships as well as competition amongst herbivores for available primary productivity. Individual taxa are defined based on body size ranges and allometry, and there are attendant rules within taxa for size at reproductive maturity and cost of growth and reproduction. Each individual makes activity and foraging decisions every fifteen minutes with consequent energy costs and probabilistic energy gains. Each day, energy is allocated amongst competing functions of maintenance metabolism, storage, and growth and reproduction depending on maturity. The animal also ages via an accumulation of free radicals depending on its metabolic rate that concomitantly increases its probability of dying of natural causes at the end of a simulated year. This simulation, carried out over many simulated years, predicts relative advantages for animals with differing metabolic allometries.