Effects of Commonly Used Garden Pesticides On the Development of a Sexually Selected Trait.

Abstract

Little is known about how chemical contaminants affect the heritability of traits and understanding this interaction is vital to knowing how populations will respond to the presence of contaminants. We used a common garden insecticide to see how it affects the development and heritability of a sexually selected trait (the posterior gnathopod) in a freshwater amphipod species. Since sexually selected traits are large sinks for resources, they may be more sensitive to environmental change than other traits. We tested two amphipod populations from different environments that likely had different exposures to pesticides. Individuals from each population were raised in low concentrations of a commonly used insecticide, malathion. The concentrations used were within the range typically found in nature. We compared the enlarged gnathopod of males to two control traits: the smaller female gnathopod and a similar-sized trait, the proximal segment of a walking leg, both of which are not under sexual selection. The research will provide insights into how manmade changes affect aquatic ecosystems, and provide knowledge of how development of organisms, including human’s morphology, are affected by the presence of chemicals.