Meeting Abstract
Cold stress can cause a number of injuries which can lead to reduced fecundity and survival. Thus, cold tolerance is tightly linked to overall fitness and ultimately is a target for selection. Further, the extent to which selection can act on cold tolerance is dictated by the degree of heritable genetic variation. In this experiment, we examined variance in cold tolerance among isogenic lines of Drosophila melanogaster to test the hypothesis that commonly used cold tolerance metrics are genetically correlated. We selected 12 isogenic lineages from the Drosophila Genetic Reference Panel with previously known variance in lower lethal temperature. For each line we analyzed acute cold shock survival (-2°C for 1 h), tolerance of chronic cold (4°C for 24h), critical thermal minimum (CTmin), chill coma recovery (CCR), and behavioral deficits in climbing performance after cold exposure (4°C for 8h). We observed significant genetic variation for every cold tolerance measure but surprisingly found that cold tolerance measures were not significantly correlated across lines. For example, some lines had high survival after cold shock but exhibited poor CCR time, while others showed the opposite pattern. Our results demonstrate that cold tolerance exhibits significant genotypic variance, but that different metrics of cold tolerance may have distinct underlying mechanisms. Ultimately, understanding patterns of phenotypic variance across various cold tolerance traits is essential for predicting adaptation to changing environmental conditions, including those brought on by climate change.
