Meeting Abstract

65.5  Monday, Jan. 6 10:30  Using Allostasis as a Foundation for Modeling Studies ROMERO, LM*; FEFFERMAN, NH; Tufts University; Rutgers University michael.romero@tufts.edu

Physiological stress is increasingly used in conservation as an index for at-risk populations. However, it is unclear how to “scale up” from individual stress responses to population-level impacts. Traditional models of stress, based upon predictability and controllability of stressors, provides little guidance. Allostasis, with its emphasis on allostatic load (cumulative increase in the cost of coping with stressors), provides a potential foundation. We used principles from allostasis to create a set of theoretical models to predict how the ability of a stressed individual to survive and reproduce will impact population sizes. Surprisingly, our models predicted the following three non-intuitive results: (1) populations where the average individual was exposed to high levels of stress relied preferentially on the oldest and most physically fit individuals for reproduction; (2) reliance on the most physically fit individuals led to the average physical condition being highest in the populations where the average individual experienced the most stress; (3) any transient perturbation in the amount of average stress exposure led to a decrease in population size. These results suggest that the average physical condition of individuals in a population may be a poor measure of how much stress the population is experiencing, that any disturbance affecting the oldest and most physically fit individuals could have a disproportionate effect on the population, and that any change in the amount of stress experienced by the average individual is likely to have a short-term detrimental impact on the population size. In conclusion, allostasis provides the theoretical underpinnings to potentially connect individual physiological responses with population-level processes.