Meeting Abstract
Thermal tolerance is an important predictor of current species distributions, the potential to invade new environments, and species’ responses to rapid climate change. There are many metrics available for measuring thermal tolerance, and each comes with its own benefits and challenges. For example, examining the effects of thermal stress on fecundity has clear ecological and evolutionary relevance, but it is labor intensive to measure. Conversely, metrics like critical thermal minimum temperature (CTmin) are high-throughput but are further removed from direct fitness consequences. Here we applied a novel assay, the Rapid Iterative Negative Geotaxis (RING) assay, to investigate sub-lethal effects of cold exposure in Drosophila melanogaster. The RING assay allows us to assess neuromuscular performance by quantifying the reaction time and climbing performance of groups of flies after cold stress. We exposed groups of flies to chilling conditions (0°C), and examined the extent to which exposure duration, recovery time, and cold acclimation prior to exposure influenced performance. Duration of cold exposure had a significant, negative impact on climbing performance, with reaction time increasing and rate of climbing decreasing as cold exposure increased from 2-24 h. However, following cold exposure of an intermediate duration (12 h), climbing performance gradually improved during recovery, with all flies regaining normal neuromuscular function within 48 hours of recovery. The final experiment assessing the impacts of cold acclimation on neuromuscular performance is currently in progress. Our results show that the RING method is a robust assay for non-invasively assessing sub-lethal cold injury and provides correlative, organismal evidence of ion homeostasis dysregulation as a possible mechanism underlying sub-lethal cold injury.
