Meeting Abstract
Changes in the environment influence ecosystems by reducing the suitability of habitats for species and by altering the strength of interspecific interactions. Both pathways change ecosystems via top-down and bottom-up processes. Temperature and external nutrients in aquatic systems effect primary production rates, and thus the growth rates of primary consumers, as well as the vulnerability of consumers to predation. Genetic variation of individuals influences such processes. In this study, we test how temperature, nutrient availability and standing genetic variation of Physa acuta affects the snail’s growth and vulnerability to predation by Procambarus clarkii. We reared snails from inbred or outcrossed lineages at high or low temperatures, with high or low resource inputs and with or without chemical cues of crayfish predation. We assessed how these treatments affected predator avoidance behavior, antipredator morphological responses, reproductive output and survival. While we found little difference in the behavioral response between treatments, we found differences in growth rates in response to resource input, standing genetic variation and temperature. Snails from outcrossed lineages were larger than inbred snails across treatments and snails only produced eggs at the lowest temperatures with the highest resource input. More eggs were laid by snails exposed to predator cues. At high temperatures, survival was reduced across treatments. We found that combined effects of resource input and temperature on growth rates influences rates of predation by crayfish, due to size dependent vulnerability. These results indicate that changes in the environment have effects on species interactions in ways that cascade through food webs and potentially change ecosystem functions.
