Predicting climate and land use change impacts on pollinators across landscapes to continents

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Human activities have created pervasive environmental changes that have accelerated extinction rates globally and in Canada. The critical factors that contribute to the loss of species - and that may degrade the services that ecosystems provide - include many well-known threats, such as habitat losses, and emerging threats, like climate change. The impacts of such global changes are widespread but enormous gaps in our understanding limit current capacities to predict future biodiversity changes. This research program seeks, as its long term objective, to understand the processes that contribute to spatial and temporal variation in species diversity. Our recent discoveries show that some of the most important pollinator groups - the bumblebees - have shown massive range losses over recent decades relative to historical baseline conditions, effects that may be a consequence of climate changes. The unusual susceptibility of these species to climate change relates to niche conservatism in their relative tolerance of warming in the hottest areas they historically occupied. This work revealed unexpected and general trends, but also showed that there is very substantial variation among species in their ranges through time. What traits might determine why some species, whether bumblebees or butterflies, succeed despite massive environmental changes, while other species decline precipitously? This proposal seeks to identify key traits that may help answer this question and to test, for the first time, the relative impacts of land use changes versus climate changes on the distributions of bumblebee species across North America and Europe. The latter project includes international collaboration that will offer particularly distinct training opportunities. Bringing together models that account for the effects of individual species' characteristics on range shifts with other models that measure how traits vary within and among species assemblages across spatial scales forms the basis of a third major project in this proposal. We will focus on butterflies for this project and include extensive field work in Ontario and Quebec. This proposal is intended to move the research program closer to its long term objective by showing how variation in critical traits, like dispersal rates, among species can affect how communities are structured from local habitats to regions. The results of this work, as with our recent discoveries, will be used to inform policy processes in Canada and internationally.