individual_collection_dataHost plant nutrition and butterfly life history and morphological data for butterflies from museum collection. Each row represents an individual butterfly. Variables determined as described in associated manuscript. Average eye width measured in mm. Wing length measured in cm. Wing length was log transformed for analyses. Nutrient data is in units of % dry mass for host plant material, calculations described in manuscript.individual_field_dataHost plant nutrition, butterfly life history and morphological data from wild-collected butterflies. Each row represents an individual. Genitalia area was measured in mm^2, and wing length in cm. Wing length was log transformed for analysis. Nutrition data measured in % dry mass, calculated as described in the manuscript. This data is needed for the example code to work. Example code is located at: https://github.com/EMSwanson/Published-papers with filename "PGLS analyses for egg number and nitrogen females.R"butterfly_treeThis file contains the phylogeny used for the analyses in the associated paper. Example code for loading phylogeny, and running PGLS analysis for fecundity and nitrogen from the "individual_field_data.csv" located at: https://github.com/EMSwanson/Published-papers with filename "PGLS analyses for egg number and nitrogen females.R".

Nutrition is a key component of life-history theory, yet we know little about how diet quality shapes life-history evolution across species. Here, we test whether quantitative measures of nutrition are linked to life-history evolution across 96 species of butterflies representing over 50 independent diet shifts. We find that butterflies feeding on high nitrogen host plants as larvae are more fecund, but their eggs are smaller relative to their body size. Nitrogen and sodium content of host plants are also both positively related to eye size. Some of these relationships show pronounced lineage-specific effects. Testis size is not related to nutrition. Additionally, the evolutionary timing of diet shifts is not important, suggesting that nutrition affects life histories regardless of the length of time a species has been adapting to its diet. Our results suggest that, at least for some lineages, species with higher nutrient diets can invest in a range of fitness-related traits like fecundity and eye size while allocating less to each egg as offspring have access to a richer diet. These results have important implications for the evolution of life histories in the face of anthropogenic changes in nutrient availability.