Fig. 4

The effect of developmental and adult temperature on the net changes in fat and glycogen stores. Net changes in fat and glycogen were significantly influenced by both developmental and adult temperatures, with the maximum net increase occurring at an optimal adult temperature of approximately 18–21 °C. Developmental temperatures also played a key role in determining the peak values. The maximum net change in fat reserves was reached at developmental temperatures of approximately 28 °C for the IN population and 23 °C for the SK population, while glycogen reserves peaked at developmental temperatures of approximately 20 °C (IN: 20.5 °C; SK: 19.5 °C). The lower (LT₀) and upper thresholds (UT₀) for zero net change, defined as the adult temperatures below and above which there is no net increase in reserves, also varied with developmental temperature. Exposure to temperatures below LT₀ and above UT₀ led to a reduction in both fat and glycogen reserves, with the LT₀ being higher and the UT₀ lower for fat compared to glycogen. The net changes were calculated as the amount of fat/glycogen in 8-day-old flies (µg per fly) minus the amount of fat/glycogen in freshly eclosed flies (µg per fly). The net changes in the amounts normalized to protein content (expressed as µg per mg protein) are depicted in Additional file 1: Fig. S6. Contour lines were computed using Delaunay triangulation, and the contour plot was smoothed with the Thin Plate Spline algorithm (OriginPro 2024 software). For statistical analyses, see Additional file 1: Tables S3, S4