Collaborative Research: ORCC: The Interplay of Plasticity and Evolution in Pierid Butterfly Responses to Recent Climate Change

Plants and animals have responded to recent climate change in a variety of different ways, highlighting the need to identify the biological mechanisms that can result in seemingly unpredictable responses. Incorporating the mechanisms into ecological and evolutionary forecasting models is essential to accurately project the biodiversity consequences of climate change.

Dramatic insect declines, including of butterflies in the Western US, reinforce the need to improve forecasts for conservation planning related to biodiversity, agriculture, and the maintenance of ecosystem services such as pollination. Will insect populations move, go extinct, or be able to adapt to future climate change? Researchers will repeat historical lab and field experiments with Pierid butterflies to ask whether evolution and developmental plasticity of larval and adult traits relevant to thermal responses have kept pace with recent climate change.

Modeling resources will be disseminated through the ‘TrEnCh’ project, which provides computational and visualization tools to Translate Environmental Change into organismal responses. Trainees will translate the research into TrEnCh-Ed inquiry-based modules with interactive data visualizations. Workshops will introduce these resources to high school and undergraduate teachers.

The proposed research will partially be conducted via course-based undergraduate research experiences (CUREs) at a community college with a diverse student body. The CUREs will introduce students to relevant concepts in plant and animal biology and to the research process. Some students will continue research and professional development training in the summer to facilitate their transition to a 4-year college and their retention in science.

The research will identify the biological mechanisms underlying evolutionary and plastic responses to climate change by quantifying how butterfly temperatures have shifted over several decades and developing a mechanistic model that links the temperature changes and traits to ecological and evolutionary responses. The following studies will test the mechanisms predicted to drive evolution and refine the model.

Repeating field selection studies will investigate whether selection on Pieris rapae larval thermal performance curves (TPCs) and on Pontia occidentalis adult body size and wing traits has shifted over time. Studying selection on several wing traits across seasons will indicate relative selective responses to thermal means versus extremes and assay whether selection varies seasonally.

The research will determine whether selection results in evolution of larval TPCs as well as adult traits and their plasticity. The project will test several hypotheses related to recent warming. Performance at high temperatures will be enhanced relative to the past.

Wing coloration involved in heat-avoidance postures will be lighter. Wing coloration involved in basking may lighten in response to climate warming, but there may be selection for wing darkening to allow for performance in cool, early season conditions. These opposing selection pressures will lead to amplified seasonal variation in selection and selection for increased plasticity.

The research will additionally assess whether genetic correlations and variation have constrained evolution and whether they have shifted over time. The research will further develop and test phenotype-based models to solve the problem of unpredictability in climate change biology.

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.