Meeting Abstract
Rapid cold hardening (RCH) is a type of phenotypic plasticity in which a short period of chilling increases tolerance to otherwise lethal temperatures. While RCH has a well-established role in protecting ectotherms against physiological damage at lethal temperatures, these temperatures are infrequently experienced in the field. However, less is known about the effect of RCH on organisms at ecologically relevant, nonlethal temperatures. To better understand the role of RCH at temperatures more commonly experienced in the field, we tested the hypothesis that RCH protects against sublethal cold injury in Drosophila melanogaster. In a preliminary experiment we measured flies’ ability to survive a 2 h cold shock between 0 and -6°C, and we found that all flies died following a 2 h cold shock at -4.5°C, while nearly 100% survive at -3°C. Thus, we are using 2 h at -3°C as our discriminating temperature to test the extent to which RCH protects against sublethal cold injury. For these experiments, adult D. melanogaster are exposed to one of three treatments: control (25° for 2 h), direct chilling (-3° for 2 h), or RCH (4° for 2 h followed by -3° for 2 h). Following these treatments, we are testing the ability of RCH to protect tissues from sublethal damage, reduce the time taken to recuperate from torpor at low temperatures, and recover locomotor activity following cold stress. Beyond the work presented here, we will test the extent to which RCH protects against suborganismal cold damage, preserves energy balance, and improves fecundity following cold stress. Together, these experiments will provide a thorough assessment of the ability of RCH to protect against sublethal cold injury.
