Meeting Abstract

52.1  Jan. 6  Increased variation in extreme environmental conditions: Adaptive response or sampling artifact? WANG, G*; FRAZIER, MR; Univ of Washington, Seattle; Univ of Washington, Seattle gw0@u.washington.edu

Trait variation is greater in stressful environments than in non-stressful environments. For example, the confidence interval of fitness in C. elegans is greatest at high temperatures. Several authors have hypothesized that increased variation in extreme environments is the result of selection. Proposed mechanisms include: 1. Direct effects of stress on recombination and mutation rates. 2. Breakdown of canalization in extreme environments. 3. Increased variability is an adaptive response which exposes underlying genetic variability to selection in extreme environments. However, these hypotheses ignore the fact that increased variation is the null expectation in steep areas of non-linear reaction norms when there is either measurement error or small lateral shifts in underlying reaction norms. We explore the effects of measurement error and changes in reaction norm shape on observed variation using both Monte Carlo simulation and published experimental datasets. We suggest analytical and experimental methods for separating the underlying causes of variation.