LTREB Renewal: Evolutionary and Demographic Responses to Climate in Natural Populations

University Of California-Irvine, Irvine CA

Investigators

Abstract

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 responds 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 interacts 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 undergraduate and graduate students and postdoctoral associates. Field science tours at the Rocky Mountain Biological Laboratory (RMBL) will be led for outreach to the general public. 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 long-term field study near the RMBL to measure natural selection on, and the extent of genetic variance in, vegetative and floral traits of Ipomopsis aggregata subspp. aggregata and Ipomopsis tenuituba (Polemoniaceae). By the end of the grant period there will be 16 to 23 years of data on selection (depending on the trait) to examine associations between selection and snowmelt date. 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 project will examine the dependence of evolutionary and demographic responses on genetic variance in traits, as measured from common gardens with a full-sib breeding design. The extent of adaptive phenotypic plasticity in response to annual snowmelt date and summer precipitation 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. 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.