Organisms encounter a wide range of toxic compounds in their environments, from chemicals that serve anti-consumption or anti-competition functions, to pollutants and pesticides. Although we understand many detoxification mechanisms that allow organisms to consume toxins typical of their diet, we know little about why organisms vary in their ability to tolerate entirely novel toxins. We tested whether variation in generalized stress responses, such as antioxidant pathways, may underlie variation in reactions to novel toxins, and, if so, their associated costs. We used an artificial diet to present cabbage white butterfly caterpillars (Pieris rapae) with plant material containing toxins not experienced in their evolutionary history. Families that maintained high performance (e.g. high survival, fast development time, large body size) on diets containing one novel, toxic plant also performed well when exposed to two other novel toxic plants, consistent with a generalized response. Variation in constitutive (but not induced) expression of genes involved in oxidative stress responses was positively related to performance on the novel diets. While we did not detect reproductive trade-offs of this generalized response, there was a tendency to have less melanin investment in the wings, consistent of the role of melanin in oxidative stress responses. Taken together, our results support the hypothesis that variation in generalized stress responses, such as genes involved in oxidative stress responses, may explain the variation in tolerance to entirely novel toxins and may facilitate colonization of novel hosts and environments.

Please see methods of paper for details. Overview: caterpillars were reared on artificial diets containing novel plant material and performance and gene expression assessed across 12 family groups. The dataset allows tests of predictions that a) performance will be correlated across toxic diets, b) variation in constitutive or induced expression of genes involved in oxidative stress responses will correlate with performance on novel toxic diets, and c) variation in performance on novel toxic diets will come with life history trade-offs. Additional data are included on consumption rates of each diet, dose-response to increasing concentrations of novel plant material for one of the three diets, and total egg production of founding mothers for each family group. This file is the raw data from all experiments included in the paper.

Please see methods of paper and "key" tab