Data from: Cold adaptation shapes the robustness of metabolic networks in Drosophila melanogaster.

When ectotherms are exposed to low temperatures, they enter a cold-induced
coma (chill coma) that prevents resource acquisition, mating, oviposition,
and escape from predation. There is substantial variation in time taken to
recover from chill coma both within and among species, and this variation
is correlated with habitat temperatures such that insects from cold
environments recover more quickly. This suggests an adaptive response, but
the mechanisms underlying variation in recovery times are unknown, making
it difficult to decisively test adaptive hypotheses. We use replicated
lines of Drosophila melanogaster selected in the laboratory for fast
(hardy) or slow (susceptible) chill-coma recovery times to investigate
modifications to metabolic profiles associated with cold adaptation. We
measured metabolite concentrations of flies before, during, and after cold
exposure using NMR spectroscopy to test the hypotheses that hardy flies
maintain metabolic homeostasis better during cold exposure and recovery,
and that their metabolic networks are more robust to cold-induced
perturbations. The metabolites of cold-hardy flies were less cold
responsive and their metabolic networks during cold exposure were more
robust, supporting our hypotheses. Metabolites involved in membrane lipid
synthesis, tryptophan metabolism, oxidative stress, energy balance, and
proline metabolism were altered by selection on cold tolerance. We discuss
the potential significance of these alterations.