COS 30-2 - Direct temperature effects and prior temperature adaptation interact to determine predator-prey dynamics and stability

Abstract: Increases in temperature with global climate change are likely to influence the dynamics of populations and communities through direct effects on species’ physiologies and, in turn, the strengths of interactions among species. Simultaneously, increasing temperatures and species introductions are also leading to shifts in species’ ranges which can lead to asymmetries in the thermal adaptation history of species. Therefore, the net effects of global change on population dynamics through temperature are likely to be influenced by both direct temperature effects and interactions between direct temperature effects and prior temperature adaptation of species. Here we directly address how direct temperature effects and prior temperature adaptation alter the dynamics of predator-prey interactions using a microcosm experiment. To do so, we used two experimental evolution populations of Paramecium bursaria that were allowed to adapt to low (20 degrees) and high temperatures (32 degrees) for hundreds of generations. We performed a factorial microcosm experiment across temperatures (20, 26, and 32 degrees) in which we followed the population dynamics of the two experimental evolution populations of P. bursaria separately in the presence of the heliozoan predator Actinosphaerium. Actinosphaerium was unable to persist in the microcosms at 32 degrees regardless of thermal adaptation history of P. bursaria. However, the predator-prey dynamics exhibited when Actinosphaerium could persist depended on both the temperature at which the experiment took place and the thermal adaptation history of the P. bursaria. Specifically, an analysis of the time series data of the predator-prey dynamics showed that temperature altered the growth of P. bursaria and the strength of its interactions with Actinosphaerium. Furthermore, the effects of temperature on P. bursaria growth and the interaction strengths with Actinosphaerium were dependent on the thermal adaptation history of P. bursaria. Overall, our results suggest that the dynamical consequences of rising temperatures for ecosystems depend not only on the direct effects that temperature has on species and their interactions but also on the thermal adaptation history of the interacting species.