Figure 1.

Experimental design of temperature manipulation. 19 colonies were used for the experiment that were either kept under constant (nine colonies; 27°C ± 0.5°C; thermometer with simple arrow) or variable (ten colonies; 27°C ± 5°C; thermometer with circular arrows) temperature conditions. For the first two months, colonies lived in a hole of their wood block, so that they were more exposed to temperature conditions. Then colony composition was recorded, and they were allowed to dig into their wood block. After another 18 months, the blocks were split, and colony composition was recorded again. At the end, queens that had survived the whole 20 months and one old worker per colony were collected for transcriptome analyses.