LTREB: Evolutionary and demographic responses to climate in natural populations

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The purpose of this study is to understand how a rapidly changing environment influences natural selection and population size. Many species of plants and animals can be threatened by rapid environmental change, such as an increase in frequency or severity of drought. This research will test the conditions required for a population to avoid collapse due to climate change through a process of adapting to the new environmental conditions. It will add to the longest-running data set on how selection in plants changes in response to changes in annual snowpack and pollinator availability, and to model for the first time how adaptation to these conditions allows populations to recover. It will determine how selective pressures change in response to water availability, how genetic variation in leaf and flower traits interact with climate change to affect birth and death rates, and how changes in pollination patterns and rates interact with the physical environment to influence evolutionary change. Responses of population size to climate change will be projected over the next century and provide a case study of how other species might respond. The project will include the training of diverse undergraduate and graduate students and a postdoctoral associate. Field science tours at the Rocky Mountain Biological Laboratory will be led for outreach to the general public and to K-12 teachers. In addition, a citizen science project will allow the public to contribute to the building of maps of pollinator abundance across the western US.This project will continue a 10-year field experiment with common gardens near the Rocky Mountain Biological Laboratory to measure natural selection on, and the extent of genetic variance in, traits of Ipomopsis aggregata subspp. aggregata and Ipomopsis tenuituba (Polemoniaceae). In combination with unique data on how absolute fitness is altered by snowmelt date, models for evolutionary rescue will be fully parameterized in nature. The relationship between selection of functional vegetative traits and water availability will be determined with two approaches: observational data on selection over two decades and a new experimental manipulation of snowmelt date and summer precipitation. The project will examine the dependence of evolutionary and demographic responses on genetic variance in traits, as measured from a full-sib breeding design. The extent of adaptive phenotypic plasticity in response to annual snowmelt date will also be incorporated into projections of population size. Although prior studies of plant adaptation to climate have emphasized vegetative traits, floral traits (shape, color, rewards, volatiles) will be modeled as well, as selection on them depends on water availability and pollinator abundance.