Grant: Discovery Grants Program - Individual

Climate change is increasing average temperatures across the globe, but also creating more variable temperature and precipitation patterns. As a result, extreme weather events are becoming more common and severe. Effects of climate change on human populations and economies are most evident when extreme weather occurs, and these events are increasingly the face of human-induced climate change. Extreme weather events also affect plant and animal populations. However, scientists only have a poor understanding of how changing extreme weather regimes will affect the ecology and evolution of organisms because the unpredictability of these events makes them hard to study. My collaborators and I have been studying populations of a high-altitude, alpine butterfly in the Canadian Rockies for almost thirty years. This system provides an excellent opportunity to understand how organisms might respond to more frequent and severe weather, and their capacity to be resilient to these changes. We know occasional extreme warm or cold temperatures in early winter kill overwintering eggs (because they either freeze or hatch too early), which reduces population size and genetic diversity. But we don't know whether populations have the necessary genetic variation to adapt to more severe and frequent early winter weather extremes. We also know that once populations crash because of extreme winter conditions, movement of adults among different populations (called `dispersal') is important for the populations to recover. As climate change pushes tree-line upslope, isolating the alpine meadows where the butterfly lives from each other, dispersal will decline. Hotter summers could further reduce dispersal, since movement of all insects is sensitive to temperature, but we don't know enough about how higher temperatures will affect insect dispersal to make this prediction. My research group will use a combination of field, lab and genomic studies to determine: (1) the capacity of this butterfly to adapt to extreme weather events in early winter, and (2) how high temperatures might affect dispersal. For (1), we will expose eggs to extreme cold and warm to see if individuals vary in the ability to survive these conditions, look for genes that are the basis of this variation, and look for evidence that past extreme weather events in early winter have caused selection for these genes. For (2), we will fly butterflies on flight-mills to see how their flight ability changes with air temperature; we will determine if individuals that have moved between populations in the wild (dispersers) are better at flying under high temperatures, what genes are responsible for differences in flight ability among individuals, and whether those genes are more common in dispersers in the wild. Our research will serve as a model for understanding how extreme weather events will affect other organisms, and the capacity of populations to resist or recover from the damage caused by such events.