Tolerance of novel toxins through generalized mechanisms: simulating gradual host shifts of butterflies

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. Variati...