Meeting Abstract
Organisms today face a range of stressful environments unknown in their evolutionary pasts. Understanding the mechanisms that promote population survival in novel environments is important not only for providing insight into how organisms may adapt to rapidly shifting anthropogenic environments, but also how organisms have adapted to past changes. One form of phenotypic plasticity, known as hormesis, might play a key role in facilitating organismal survival in novel environments. Hormesis is a phenomenon where exposure to low levels of stress in early life induce developmental changes that prime the organism to better tolerate subsequent stress exposure later in life. Evidence for hormesis is widespread, and such effects have been reported in diverse taxa in response to hundreds of stressors (e.g., chemical stress, temperature, and ionizing radiation). While the benefits of hormesis are clear, its pervasiveness raises an important question: why are hormetic responses not produced all the time but instead require a sensitizing stress exposure to occur? I conducted a multiple-family experiment rearing cabbage white butterflies (Pieris rapae) across a broad range of dietary zinc doses to test whether families with greater hormetic responses to zinc face a tradeoff with fecundity under control conditions – in other words, the ability to mount a hormetic response is itself costly. Preliminary results indicate genetic variation for survival, development time and body size on zinc-dosed diets with some families showing apparent hormetic (i.e., positive) responses to low zinc doses. This work will inform models of plastic and evolutionary rescue, theory on costs of plasticity, and emerging observations on costs of hormesis.
