Drosophilid cuticle pigmentation impacts body temperature

Abstract

AbstractCuticle pigmentation has been clearly demonstrated to impact body temperature for several relatively large species of insects, but it was questioned for small insects. Here we used a thermal camera to assess the impact of drosophilid cuticle pigmentation on body temperature when individuals are exposed to light. We compared mutants of large effects within species (Drosophila melanogaster ebonyandyellowmutants). Then we analyzed the impact of naturally occurring pigmentation variation within species complexes (Drosophila americana/Drosophila novamexicanaandDrosophila yakuba/Drosophila santomea). Finally we analyzed lines ofD. melanogasterwith moderate differences in pigmentation. We found significant differences in temperatures for each of the four pairs we analyzed. The temperature differences appeared to be proportional to the differently pigmented area: betweenDrosophila melanogaster ebonyandyellowmutants or betweenDrosophila americanaandDrosophila novamexicana, for which the whole body is differently pigmented, the difference in temperatures was around 0.6°C ±0.2°C. By contrast, betweenD. yakubaandD. santomeaor betweenDrosophila melanogaster DarkandPalelines, for which only the posterior abdomen is differentially pigmented, we detected a temperature difference of about 0.14°C ±0.10°C. This demonstrates that cuticle pigmentation has ecological implications in drosophilids regarding adaptation to environmental temperature.