Collaborative Research: ORCC: Climate change responses in a globally invasive insect: Quantifying the roles of local adaptation, seasonal adaptation, and phenotypic plasticity

Commonly known as the “spotted wing Drosophila,” Drosophila suzukii has become one of the most captivating cases of rapid worldwide invasion. Originally from southeast Asia, this fruit fly was first recorded in California in 2008 and has since spread to 48 of 50 states in the US, with parallel expansions occurring in Europe. In addition to its intriguing invasion biology, D. suzukii is a significant pest that causes up to $500 million in annual losses to US agricultural efforts. The proposed work will create long-term collaborations with local farmers and naturalists across Vermont and Kentucky to understand the genetic, physiological, and ecological underpinnings of D. suzukii’s success as an invasive species in the context of a rapidly changing world. Of particular interest to the work is D. suzukii’s capability to develop into summer-specialized and winter-specialized “morphs,” a physiological feature that plays a key role in their success and hardiness as invaders. The PIs will combine physiological experiments, genomics, and computer simulations to predict how these traits will evolve under various climate change projections. They will focus on the capacity of the fly to expand its habitat into northern latitudes as colder winters, an ecological delimiter for D. suzukii, continue to weaken due to climate change. They will also develop a summer science module for K-12 students focused on horticulture, invasive species, and climate change, and lesson plans from these modules will be published in peer-reviewed science education journals. The project will train multiple undergraduate interns, two graduate students, and a postdoc. Global climate change has introduced novel stressors to many habitats, and it is unclear which species may emerge as winners or losers in a changing world. To date, most efforts in climate change biology have focused on traits important for coping with extreme heat events. Yet, winter temperatures are warming twice as fast as summer temperatures in North America, and the evolutionary consequences of more heterogeneous winters remain understudied. This is a critical knowledge gap given that species distributions are often limited by minimum winter temperatures. Quantifying factors that shape winter biology is critical for predicting organismal responses to changing climates. This proposal investigates the relative contributions of plasticity, local adaptation, and seasonal adaptive tracking in fine-tuning key overwintering traits in D. suzukii. The PIs will use flies from Vermont and Kentucky to quantify genetic variation in cold tolerance, overwintering survival, and post-winter reproduction, as well as the reaction norms of these traits in summer/winter seasonal morphs. They will use whole genome resequencing to determine whether D. suzukii has persistent overwintering populations and the extent to which genetic structure is shaped by adaptive tracking. Lastly, they will create a novel set of simulations to explore how plasticity, local adaptation, and adaptive tracking evolve in a metapopulation that experiences fluctuating stressors. They will also incorporate projections into our simulations to predict how reaction norms for overwintering traits evolve in response to climate change. As the species of study is a major agricultural pest, the work is relevant to the bioeconomy. This project is jointly funded by Integrative Ecological Physiology (IOS/IEP) and the Established Program to Stimulate Competitive Research (EPSCoR). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.