Meeting Abstract

132.2  Tuesday, Jan. 7 13:45  Toxicity of a Current-Use Insecticide to Daphnia pulicaria: Impact of 500 Years of Evolution SIMPSON, A.M.*; BELDEN, J.B.; JEYASINGH, P.D.; Oklahoma State University; Oklahoma State University; Oklahoma State University adam.simpson@okstate.edu

This study examined how the natural evolutionary progression in a resurrected Daphnia pulicaria population indirectly affected its sensitivity to new anthropogenic stressors, specifically pesticides. Toxicity of the organophosphate insecticide chlorpyrifos was determined through a series of acute toxicity tests quantified by the median lethal concentration (LC50). After comparing LC50 values across clone genotypes, a trend can be seen demonstrating an increased sensitivity to chlorpyrifos in the ancient clones. This could be explained by a pre-evolved decrease in metabolism in the more contemporary clones. Ultimately, these results provide preliminary insight into preexisting mechanisms that confer developed resistance to new environmental stressors.