Data from: How temperature shifts affect parasite production: testing the roles of thermal stress and acclimation

1. Changes in the magnitude and frequency of temperature shifts with climate change will influence species interactions if species have differential acclimation responses. For example, if parasites acclimate to temperature shifts faster than their hosts, as might be expected due to their smaller sizes and faster metabolisms, temperature variability could lead to increased infection. However, this assumption might not hold if benefits of acclimation are counteracted by energetic costs or thermal stress, underscoring the need for empirical efforts to assess how temperature variability will influence host-parasite interactions. 2. We used an array of replicate incubators to test how temperature shifts from five acclimation temperatures (13-25°C) to five performance temperatures (16-28°C) influenced release of infective stages by the trematode parasite, Ribeiroia ondatrae, from its snail intermediate host (Helisoma trivolvis) at four time points after a temperature shift. 3. Initially, parasite release was higher at warm temperatures and increased temporarily after infected snails were shifted to higher temperatures, particularly for hosts acclimated to cooler temperatures. However, these effects were transient, such that parasite release at warm temperatures declined steadily over the seven days following the shift. Warmer temperatures also increased snail mortality. 4. Parasite release was strongly influenced not only by ambient temperature but also by the thermal history of the host. Prior acclimation to warm temperatures reduced parasite release at warm performance temperatures, contrary to the beneficial acclimation hypothesis. Rather, the observed pattern was likely driven by: (1) energetic costs of prolonged exposure to high temperatures (“thermal stress”) or (2) parasites’ capacity to “store” infectious stages at cooler temperatures. 5. The time-dependent nature of thermal effects on parasite performance highlights the importance of considering the amplitude and frequency of temperature variability for understanding future changes to disease dynamics