Meeting Abstract

P3.2  Wednesday, Jan. 6  Turning Up the Heat: Using Thermal Extremes to Test an Optimality Model of Developmental Acclimation THARP II, J. M.*; JERNBERG, I.; COOPER, B. S.; ANGILLETTA JR. , M. J.; Indiana State Univ; Indiana State Univ; Indiana Univ; Indiana State Univ jtharp5@indstate.edu

Although much evidence for developmental acclimation exists, researchers still know little about why organisms acclimate the way that they do. Recent theoretical models suggest that populations should evolve genotypes with the capacity to acclimate only when the environment varies among generations. In this study, we compared the developmental acclimation of fruit flies (Drosophila melanogaster) from two populations, one from a subtropical environment (Miami, FL) and the other from a temperate environment (Marlton, NJ). We allowed flies from each population to develop in one of three environments: 1) a stochastically varying environment with a mean of 18°C, 2) a stochastically varying environment with a mean of 25°C, and 3) a constant environment with a mean of 25°C. After flies reached adulthood, we quantified heat and cold tolerances of flies from each developmental environment and each population. Heat tolerance was quantified as the time for a fly to lose mobility when exposed to 41°C (knockdown time). Cold tolerance was quantified as the time required for a fly to recover from a cold-induced coma (chill-coma recovery time) We predicted that flies from NJ would have greater developmental plasticity and thus display greater heat tolerance and cold tolerance than FL flies. Knockdown time acclimated in a manner that was consistent with our prediction (e.g. flies from NJ could withstand heat longer than those from FL when both were raised at 25°C). However, chill-coma recovery did not acclimate differently between the two populations; flies from both populations recovered more quickly when raised at 18°C than when raised at 25°C, and recovery times did not differ between populations. Our results suggest that new models are needed to better understand the acclimation of thermal tolerance.