Biological diversity is increasingly being shaped by environmental change. We use a combination of experiments, observations, and models to investigate the evolutionary and demographic processes that determine how populations persist and adapt in novel and fluctuating environments.
Alpine bistort tubers from throughout the species' latitudinal range transplanted into a common garden in the Wrangell Mountains of Alaska
How does local adaptation alter demographic responses to climate change?
Most populations are locally adapted to a narrower range of environmental conditions than experienced throughout the species range. Theory predicts that local adaptation to historical climate can alter responses to climate change, both in local populations and range-wide. As part of an NSF-funded Long-Term Research in Environmental Biology project, with co-PIs Dan Doak (CU Boulder), Bill Morris (Duke University), and Meredith Zettlemoyer (University of Montana), we are investigating the competing effects of local adaptation and phenotypic plasticity in determining climate change responses for two alpine plants, moss campion (Silene acaulis) and alpine bistort (Bistorta vivipara). By combining long-term demographic data with climate manipulation and common garden experiments, we're testing the effects of local adaptation on predictions of species' distribution and abundance under climate change.
Related papers:
Most populations are locally adapted to a narrower range of environmental conditions than experienced throughout the species range. Theory predicts that local adaptation to historical climate can alter responses to climate change, both in local populations and range-wide. As part of an NSF-funded Long-Term Research in Environmental Biology project, with co-PIs Dan Doak (CU Boulder), Bill Morris (Duke University), and Meredith Zettlemoyer (University of Montana), we are investigating the competing effects of local adaptation and phenotypic plasticity in determining climate change responses for two alpine plants, moss campion (Silene acaulis) and alpine bistort (Bistorta vivipara). By combining long-term demographic data with climate manipulation and common garden experiments, we're testing the effects of local adaptation on predictions of species' distribution and abundance under climate change.
Related papers:
- DeMarche et al. 2019. Incorporating local adaptation into forecasts of species' distribution and abundance under climate change. Global Change Biology 25:775-793.
- Chardon et al. 2019. Incorporating intraspecific variation into species distribution models improves distribution predictions, but cannot predict species traits for a widespread plant species. Ecography 42:1-15.
- DeMarche et al. 2018. Both life history plasticity and local adaptation will shape range-wide responses to climate warming in the tundra plant Silene acaulis. Global Change Biology 24:1614-1625.
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How do evolutionary and migratory potential drive range-wide population dynamics under climate change?
Populations across species' ranges likely vary in their migratory and adaptive potential under climate change, yet we lack a comprehensive understanding of which populations are most vulnerable to climate change because forecasts of range shifts often fail to account for population-level variation in plasticity and genetic variation. We ask: to what extent can we improve mechanistic predictions of range dynamics under climate change by modelling genomic variation, gene flow rates, plasticity, and additive genetic variances in traits and fitness? This NSF-funded Organismal Response to Climate Change project involves a highly collaborative team of researchers, including Jill Anderson (University of Georgia), Susana Wadgymar (Davidson College), Emily Josephs (Michigan State University), Seema Sheth (North Carolina State University), and Jenny Cruse-Sanders (State Botanical Garden of Georgia). We are combining approaches from evolutionary biology, field ecology, and population genomics to forecast range-wide dynamics under climate change in a native legume (Chamaecrista fasciculata) that is broadly distributed across central and eastern North America. Our work will provide a robust framework for predictions of range-wide responses to climate change in systems that are less amenable to manipulation. We are collaborating with conservation practitioners in the Georgia Plant Conservation Alliance and Southeastern Grasslands Initiative to produce risk assessment tools that project range dynamics under climate change for endangered plant species. Related papers: |
We combine distributed common garden and climate manipulation experiments with genomic estimators of historical gene flow to forecast evolutionary and migratory potential in partridge pea (Chamaecrista fasciculata)
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Can shifting phenology buffer populations from climate change?
Changes to species phenology, or the timing of key life history events such as germination or flowering, are among the strongest and most consistent biological responses to climate change. Yet we still have surprisingly little understanding of how shifting phenology affects individual fitness or population dynamics under climate change. In collaboration with Meredith Zettlemoyer (University of Montana), we are examining the direct and indirect effects of advancing flowering on fitness and population persistence in a suite of co-flowering alpine plants.
Changes to species phenology, or the timing of key life history events such as germination or flowering, are among the strongest and most consistent biological responses to climate change. Yet we still have surprisingly little understanding of how shifting phenology affects individual fitness or population dynamics under climate change. In collaboration with Meredith Zettlemoyer (University of Montana), we are examining the direct and indirect effects of advancing flowering on fitness and population persistence in a suite of co-flowering alpine plants.
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How do populations persist in variable environments?
Natural populations experience fluctuating environmental conditions across space and time. Several projects in the lab explore the range of processes that allow small populations to persist over long time periods in the face of environmental variability. A long-standing observation in flowering plants has been that isolated or ecologically marginal populations often have higher self-fertilization rates (‘Baker’s Law’), suggesting that this could be an important mechanism enabling population persistence. Diverse responses to environmental variation can also act to stabilize ecological systems. Although diversity-stability relationships have been most intensively studied at the community level, with an emphasis on diversity of species or functional groups, individuals within populations can also differ in traits that govern responses to environmental variation. We use a combination of individual-based simulation models and long-term census data to test these mechanisms in a variety of systems. |
The extremely rare plant Saussurea weberi is endemic to limestone soils in the Rocky Mountains (left). Population stability over the last 20 years has been driven by diverse local responses to July temperature variability, but this stability has eroded as plants have been responding more synchronously during the warmest years (right).
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Related papers:
- Louthan et al. 2021. Climate sensitivity across latitude: scaling physiology to communities. TREE 36: 931-942.
- Dibner et al. 2019. Multiple mechanisms confer stability to isolated populations of a rare endemic plant. Ecological Monographs 89:e01360.
- Abbott et al. 2017. Portfolio effects, climate change, and the persistence of small populations: analyses on the rare plant Saussurea weberi. Ecology 98:1071-1081.
- Peterson and Kay. 2015. Mating system plasticity promotes persistence and adaptation of colonizing populations of hermaphroditic angiosperms. American Naturalist 85:28-43.
