This session will focus on climate change adaptation and assisted gene flow in natural plant populations. Let's exchange experiences, best practices, and policies to guide ecologically informed applications of assisted gene flow.
SESSION CHAIRS Professor Jason Sexton1, Professor Elsa Cleland2, Dr. Benjamin Blackman3
1University of California, Merced, Merced, CA, United States. 2University of California, San Diego, La Jolla, CA, United States. 3University of California, Berkeley, Berkeley, CA, United States
Professor Jason Sexton
University of California, Merced
Jason (Jay) Sexton is an Associate Professor in the Life and Environmental Sciences Department, University of California, Merced. He studies plant climate adaptation and the determinants of plant distribution limits. His lab group mainly studies the ecology, evolution, and conservation biology of forest and meadow plant ecosystems of the Sierra Nevada and vernal pool systems of the Great Central Valley. Jay also serves as the Faculty Director of the UC Merced Natural Reserve System.
Professor Elsa Cleland
University of California, San Diego
Prof. Cleland has been researching plants in California for over 20 years. Her focus is in understanding the ecological and evolutionary potential for native species to respond to global changes such as invasion and climate change. The ultimate goal is to contribute to sound strategies for plant conservation and restoration.
Dr. Benjamin Blackman
University of California, Berkeley
Dr. Blackman’s work addresses fundamental questions about genetics of adaptation, the evolution and ecology of development, and mechanisms of gene-environment interaction. Ben graduated with a BS in Biological Sciences from Stanford, and he completed his PhD at Indiana University, Bloomington with Drs. Loren Rieseberg and Scott Michaels, studying the evolution of developmental timing during sunflower domestication and adaptation. As a postdoc at Duke, Ben began studying the genetics of adaptation in monkeyflowers with Dr. John Willis. In 2012, Ben became a faculty member in the Department of Biology at University of Virginia and moved to the University of California at Berkeley in 2016. There, he continues to examine the genetics and ecology of adaptation in both plant species, including projects on solar tracking and ancient DNA genomics in sunflower, and on floral pigmentation patterning and adaptation to drought and challenging soils in monkeyflower.
10.1 Consequences of Assisted Gene Flow on Threatened Annual Monkeyflower Populations
Dr. Nicholas J. Kooyers1, Ms. Donna M. Hinrich1, Ms. Courtney M. Patterson2, Ms. Andrea K. Turcu1, Mr. Simon G. Innes1, Mr. Stacy D. Holt1
1University of Louisiana, Lafayette, LA, United States. 2Hernández Bioinformatics, Saskatoon, SK, Canada
Description Assisted gene flow (AGF), the human-aided movement of individuals between populations, is a controversial management practice intended to provide an influx of adaptive genetic diversity into threatened populations to mediate evolutionary rescue. While AGF is already being used for the conservation of threatened species, the practice has largely been assessed only through simulation and laboratory experiments. Questions remain regarding which germplasm should be introduced, the consistency and timeframe of evolutionary rescue, and the degree of introgression into native populations. We assess these questions by conducting a landscape-level AGF experiment in threatened populations of the yellow common monkeyflower (Mimulus guttatus) and evaluated genomic, phenotypic and fitness variation in the three years before and after AGF. Our results indicate that AGF has strong effects in some experimental populations, particularly when seeds rather than seedlings were introduced. AGF led to an experiment-wide increase of 19.4% and 18.8% in the number of flowers and number of seeds produced, respectively, in populations where source seeds were introduced. Fitness increases were associated with flowering earlier and producing fewer trichomes. Introgression from source populations occurred into half of the target populations. Introgression was relatively uniform across the genome, but introgressed alleles almost universally remained at low frequency (< 10%) and populations retained native genetic diversity. Both the amount of introgression and fitness changes were heterogenous between years, with larger impacts in more historically-normal years. While our results are generally consistent with theoretical models, rapid adaptation within subsets of populations provides cautious optimism for an often-maligned conservation strategy.
Presenter Bios
Dr. Nicholas J. Kooyers
University of Louisiana, Lafayette
Dr. Nicholas Kooyers is the Harold & Adele Comeaux/BORSF Endowed Professor of Biology at University of Louisiana, Lafayette and has spent the last 15 years conducting plant evolutionary ecology and genetic studies in Sierra and Oregon Cascades. His research broadly focuses on the impact that rapid selection and adaptation can have in plant populations. Specifically, he is most interested in whether adaptation to changing climates can mitigate population declines and whether adaptation can cause introduced species to become more invasive. He lives in Lafayette, Louisiana with his wife, Loren and their two children, Blake and Cassin, and is constantly expanding his garden to match the vision of his toddler managers and the Acadiana Native Plant Project.
10.2 Assisted Gene Flow, Not Assisted Migration, May Facilitate High Elevation Population Persistence for Mountain Jewelflowers
Dr. Brandie Quarles-Chidyagwai, Sarah Ashlock, Dr. Jennifer R Gremer, Dr. Julin N Maloof
University of California, Davis, Davis, CA, United States
Description With ongoing climate change, plant species will have to track changes in the environment through adaptation or dispersal. High elevation populations are at risk due to warming temperatures, reduced snowpack, and shifting growing seasons. Upslope dispersal from low elevation populations pre-adapted to warm temperatures may facilitate population persistence at high elevations. However, with large seasonal differences across elevations, it is unclear if low elevation populations will be able to shift their life cycles to avoid winter snowpack and be successful.
We conducted a common garden study with Streptanthus tortuosus (mountain jewelflower) at high elevation. 23 populations from across the species range were measured for mortality, phenology, and reproductive output.
Results show that low elevation populations from warmer sites than the high elevation garden had the highest survival through the first year. Surprisingly, low elevation populations were also able to survive through the winter better than high elevation populations. However, survival to reproduction in year two was higher for high elevation populations from sites with similar temperatures as the garden. Thus, assisted migration alone may not be a successful conservation strategy as low elevation populations' fitness is lower in their second year of life. Instead, strategic assisted gene flow that combines low elevation alleles that allow for high first year survival with high elevation alleles that facilitate reproductive success in the second year may be more appropriate. We are currently analyzing crosses between low and high elevation populations to begin to assess which population combinations show the most promise.
Presenter Bios
Dr. Brandie Quarles-Chidyagwai
University of California, Davis
Dr. QC is an evolutionary ecologist working as a postdoctoral scholar at UC Davis in the Gremer and Maloof labs. She received her PhD in Biology from the Donohue Lab at Duke University. At UC Davis, Brandie is studying climate adaptation, population demography, and the potential for assisted gene flow in the mountain jewelflower.
10.3 Establishing Climate-Wise Seed Lot Selection for Sierra Nevada Reforestation
Dr. Sarah M. Bisbing
University of Nevada, Reno, Reno, NV, United States
Description Use of locally adapted seed has long been the foundation of reforestation, but the “local is best” seed source policy is likely to drive regeneration failures in long-lived tree species if local populations are maladapted to novel climate change conditions. This is particularly concerning for reforestation in California, where, from 2012 to 2021, elevated tree mortality from wildfire, drought, beetles, and pathogens occurred on ~10 million ha (>75% of forest land base). Seed availability is limited under such conditions, and business-as-usual reforestation efforts are likely to lead to short-term (i.e., low initial survival) or long-term (i.e., maladaptation over time) regeneration failures. Foresters can instead improve adaptive capacity through a portfolio strategy that includes locally adapted lots while simultaneously “assisting” migration of climate-wise seed lots. Here, we tested the degree of local adaptation and adaptive capacity in 60 seed lots of five of the Sierra Nevada’s most ecologically and economically important conifers to inform climate-wise reforestation. Across 27 common gardens over nine sites and four degrees of latitude, we learned that Pinus jeffreyi is overwhelmingly the most resistant to local conditions and has the potential for a high degree of adaptive capacity. We also learned that, despite high initial mortality, Calocedrus decurrens persisted once established. Overall, assisted seed lots had higher survival in cooler, wetter sites, though each species had a few strongly locally adapted populations as well as populations that thrived under more stressful conditions. Tolerance curves will inform climate-wise seed selection for reforestation across the Sierra Nevada mixed-conifer forest.
Presenter Bios
Dr. Sarah M. Bisbing
University of Nevada, Reno
Dr. Bisbing is an Associate Professor of Silviculture at the University or Nevada, Reno and Director of UNR's School Forest. Her research tests theoretical concepts to inform climate change mitigation in forests of western North America.
10.4 Native Seed Producers Can Play a Proactive Role in Conservation Genetics
Dr. Julia S. Michaels
Hedgerow Farms, Winters, CA, United States
Description Whether intentionally or unintentionally, seed producers play a role in influencing the flow of genes within and between native plant populations. Every aspect of our work, including wildland seed collection, field grow-outs, and seed mix design, has the potential to influence the genetics of the species being sown into restoration projects.
While some practitioners go to great lengths to avoid any direct influence of seed choice on genetic structure, others are exploring assisted gene flow as a conservation tool. Seed producers must therefore closely align with the shifting and variable needs of the botanists that use our seed. In this presentation, we draw on lessons learned from 40 years of native seed production to show how growers can take a proactive approach, (1) identifying geographic gaps in ecotype availability within our inventory (2) closely tracking research and funding to anticipate future demand for specific ecotypes and (3) working with scientists to develop a list of ‘priority’ species that have been shown to have especially high genetic variability across ecotypes.
Presenter Bios
Dr. Julia S. Michaels
Hedgerow Farms
Julia Michaels completed her PhD in Ecology at UC Davis where she focused her research on strategies for restoring native California vernal pool wetlands. She is currently the Restoration Ecologist at Hedgerow Farms, and President of the California Native Grasslands Association.
10.5 Panel of Speakers
Dr. Nicholas J Kooyers1, Dr. Brandie Quarles-Chidyagwai2, Dr. Sarah M Bisbing3, Dr. Julia S Michaels4
1University of Louisiana, Lafayette, LA, United States. 2University of California, Davis, Davis, CA, United States. 3University of Nevada, Reno, Reno, NV, United States. 4Hedgerow Farms, Winters, CA, United States.
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The mission of the California Native Plant Society is to protect California’s native plants and their natural habitats, today and into the future, through science, education, stewardship, gardening, and advocacy.
DateThursday, February 5
