Figure 2:

The temperature tolerance of D. silvestris and D. sproati. (A) Proportion of Hawaiian picture-wing Drosophila that survived after heat stress for males and females from the Saddle Road (SR) and South Kona Forest Reserve (SKFR) for each species. Flies that were standing and walking after exposure were counted as survivors. More D. sproati survived the heat stress compared with D. silvestris (overall model, G = 91.116, d.f. = 9, P-value < 0.001, n = 272). (B) Sperm mobility scores of sexually mature males from both populations in control (16°C) and heat (30°C) treatments. Sperm from D. sproati were more mobile than D. silvestris sperm after heat treatment (overall model, G = 29.171, d.f. = 8, P-value < 0.001, n = 77). (C) Proportion that survived after cold stress at 2°C for 1.5 h (overall model, G = 43.088, d.f. = 7, P-value < 0.001, n = 243). Flies that were standing and walking after exposure were counted as survivors. More D. silvestris survived the cold shock compared with D. sproati (D. silvestris, $\overline{x}=0.68$, 1 SEM = 0.0424, n = 122; and D. sproati, $\overline{x}=0.28$, 1 SEM = 0.0410, n = 121; P = 0.022). The mean values ± 1 SEM are reported.