Our most pressing ecological priority is to determine how human activity is driving global shifts in biodiversity and how we can balance preserving ecosystem function with the needs of a growing human population. The PI proposes new ecological research on the Pierid family of butterflies that have been the subject of research on thermal responses over the last 40 years. The overarching goal of this research is to extend and generalize Species Distribution Models (SDM), the dominant modeling approach to understanding large-scale shifts of biodiversity in the face of global change. The PI will leverage that 40 year legacy of thermal response research to develop general models of how butterflies respond to changing environments. In order to verify how well these models perform and their ability to make both species-specific and general predictions, models will be validated with large-scale monitoring data sets. There is a growing resource of citizen-science monitoring data but there are also several NSF-funded academic monitoring programs that have occurred over the years. Another aspect of this project is to bring together those academic and citizen science data into a unified publicly-available data set. The research is expected to advance macrosystems ecology study of thermal ecology and responses of biodiversity, especially ectotherms while also serving as a strong demonstration of data reuse by focusing on a well-studied and wide-spread group of butterfly species, the Pierids. Research in macrosystems ecology requires two disparate ecological data types that are rarely generated or employed by the same research community: mechanistic, experimental data and data from large spatiotemporally-replicated monitoring programs. The two dominant environmental factors driving the distribution and abundance of butterflies are thermal environment (impacted by climate) and host-plant availability (impacted by land use change and climate). There are 14 previous and current NSF-funded projects focused on primarily thermal, but also nutritional drivers of performance in one family of butterflies, Pierids. Thermal environments have several impacts on butterfly performance. Indirectly, temperature drives the seasonal timing and distribution of host-plant (food) resources. It also provides energy for growth for developing caterpillars. Host-plants are also a key component of butterfly development, not just for the obvious reason that they acquire all their nutrition for growth from these plants, but the quality of the plants also determines their growth rate. There has been a long legacy of research on the thermal and nutritional constraints of growth for many insects, but these models have not yet been fully employed to make range-wide predictions for butterflies. We propose to bring together a legacy of NSF-funded research on butterfly responses to environmental change with long-term monitoring data that can be used, respectively, to generate and test mechanistic SDMs over multiple spatiotemporal scales.