Collaborative Research: Consequences of habitat heterogeneity and seed dormancy for adaptation at the margins of a native plant population

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The principal objective of this project is to understand how environmental and genetic factors affect local expansion of plant species' ranges. Although in recent years many models have been developed to address this issue, little has been done empirically to test developed theories. This study combines field experiments and modeling to understand how range expansion in plants may be influenced by adaptation at population margins, by changes in environmental variability across population boundaries, and by dispersal of dormant seeds beyond those boundaries. Seeds of known genetic backgrounds will be transplanted in two successive years into multiple sites spanning the local population boundary of an annual plant native to California. This boundary occurs along a transition between serpentine grassland harboring high native plant diversity and a non-serpentine grassland dominated by invasive, non-native species. Concurrently, these researchers will develop new mathematical models to elucidate how dispersal, habitat variability and adaptation influence local range expansion. The models will be parameterized using data from the field experiments to estimate average survival and reproduction, as well as variation in those vital rates among sites, years and genotypes. Our integrative approach will advance conceptual and empirical understanding of how dispersal, dormancy and adaptation shape plant distributions over time. Broader impacts of this project include conservation, training advanced students, and public education. Studying mechanisms of range expansion is important for understanding how invasive plants adapt as they expand into new habitats and for predicting conditions under which plant species shift their geographic distributions in response to rapid environmental change. Both contexts are especially relevant for plant communities found on unusual substrates, like serpentine soils. Such habitats are a special conservation concern since many of their native plant species are rare and unique, and because their plant communities are threatened by invasive species. The project will support and train university students and post-doctoral fellows from under-represented groups in environmental biology, and will include science-based outreach to, and curriculum development for, local California public school students in grades 1-7.