Cold tolerance of the five Drosophila species stocks used in this study.
Cold tolerance was measured as (A) chill coma onset temperature (CTmin), (B) time to stand following 4 h at 0 °C (chill coma recovery time, or CCRT) and (C) the temperature that causes 50% mortality (quantified 24 h after a 2 h cold exposure, or LTe50). CTmin and LTe50 values are derived from a recent study on the same fly stocks6. Species are colour-coded according to their cold tolerance (warm colours indicate chill susceptible species and cool colours indicate chill tolerant species). All values are mean ± sem. Error bars that are not visible are obscured by the symbols.