Mismatches in thermal performance between ectothermic predators and prey alter interaction strength and top-down control

Climate change can alter predator-prey interactions when predators and prey have different thermal preferences as temperature change can exacerbate thermal mismatches (also called thermal asymmetry) with population-level consequences. We tested this using micro-arthropod predators (Stratiolaelaps scimitus) and prey (Folsomia candida) that differ in their temperature optima to examine predator-prey interactions across two temperature ranges, a cool (12 and 20 degrees C) and warm (20 and 26 degrees C) range. We predict that the lower thermal preference and optimum in F. candida will alter top-down control (i.e., interaction strength) by predators with interaction strength being strongest at intermediate temperatures, coinciding with F. candida thermal optimum. Predators and prey were placed in mesocosms, whereafter we measured population (predator and prey abundance), trait-based (average predator and prey body mass, and prey body length distribution), and predator-prey indices (predator-prey mass ratio (PPMR), Dynamic Index, and Log Response Ratio) to determine how temperature affected their interactions. Prey populations were the highest at intermediate temperatures (average temperature exposure: 16-23 degrees C) but declined at warmer temperatures (average temperature exposure: 24.5-26 degrees C). Predators consistently lowered prey abundances and average prey mass increased when predators were added. Top-down control was the greatest at intermediate temperatures (indicated by Log Response Ratio) when temperatures were near or below the thermal optimum for both species. Temperature-related prey declines negated top-down control under the warmest conditions suggesting that mismatches in thermal performance between predators and their prey will alter the strength and dominance of top-down or bottom-up forces of predator-prey interactions in a warmer world.

Automated summary

Climate change affects predator-prey interactions by exacerbating thermal mismatches between predators and prey. In this study, we used micro-arthropod predators (S. scimitus) and prey (F. candida) to examine their interactions at different temperatures. We found that the lower thermal preference of F. candida altered top-down control by predators, with the strongest interaction strength at intermediate temperatures. Prey populations were highest at intermediate temperatures but declined at warmer temperatures. The results suggest that mismatches in thermal performance between predators and prey will impact predator-prey interactions in a warmer world.