Data on heat tolerance for D latus from: Does plasticity in thermal tolerance trade off with inherent tolerance? The influence of setal tracheal gills on thermal tolerance and its plasticity in a group of European diving beetles

Dataset on heat tolerance used in the study by Verberk et al., (2018). Method description We assessed the impact of mode of respiration on heat tolerance under different oxygen conditions in one of the 15 species: D. latus, the most tolerant species in our comparison, using previously described methods (Verberk and Calosi, 2012, Verberk and Bilton, 2015). Briefly, individuals were placed in flow-through chambers, whose water supply could be heated. For one group of animals, we used chambers where the animals were completely submerged and had no access to air, while for a second group of animals chambers were used with a small head space holding a layer of air, meaning that these animals could obtain oxygen either from the air compartment by surfacing or from the water with oxygen diffusing directly into their tracheal system via the setae or oxygen diffusing into their subelytral air reservoir via their physical gill. Individuals were left to settle for 1 h at the equilibration temperature of 10 °C, after which the temperature was ramped up at 0.25 °C min−1. The CTmax was defined as the point at which animals lost coordinated swimming, hence losing their ability to escape from the conditions that will lead to their death (Lutterschmidt and Hutchison, 1997). The heating rate, endpoint and starting temperature all therefore differed from the methodology described above, meaning that the critical thermal temperatures from both methods cannot be compared directly. CTmax was assessed under normoxia, hypoxia and hyperoxia conditions (5, 20, 60 kPa O2 respectively) and adults were assessed with and without access to air. Oxygen tension of both the water and the air in the headspace was altered to produce hypoxia and hyperoxia, as described by Verberk and Bilton (2015).