Franks Lab
Research Projects
Rapid Experimental Evolution
Contemporary Evolution from Climate Change
Ecology and Evolution of Invasive Plants
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Our lab investigates plant evolutionary ecology. Major research areas include contemporary evolutionary responses to climate change and dynamics of invasive species. Here are examples of key projects, discoveries and resources:
A climatic change caused rapid evolution in an annual plant. We found that a multi-year drought in southern California caused evolution of earlier flowering, allowing drought escape in Brassica rapa (field mustard). An experimental evolution study showed that experimental drought also caused the evolution of earlier flowering time, and this evolution was largely parallel for phenotypic traits but
mainly non-parallel at the genetic level. These studies used the resurrection approach of comparing ancestors and descendants under common conditions.
We created a seedbank for the study of evolution. Project Baseline was formed to collect seeds of multiple species from many populations throughout the continental U.S. to allow the resurrection approach to be used to study evolution in natural populations in response to changing environmental conditions. This resource is now available for use.
We found unexpected genetic diversity in an invasive plant. Reynoutria japonica (Japanese knotweed) is one of the most problematic invasive plants in North America. Despite extensive clonal reproduction, we found that American populations had higher than anticipated genetic diversity. However, there was no evidence for genetic structure or local adaptation, also unexpected due to its high degree of success and likely reflecting colonization history. Current work on this species is examining plant-soil feedbacks and how these may influence population and community dynamics.
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1 Franks, S. J., Sim, S. & Weis, A. E. Rapid evolution of flowering time by an annual plant in
response to a climate fluctuation. Proceedings of the National Academy of Sciences of the United States of America 104, 1278-1282, doi:10.1073/pnas.0608379104 (2007).
2 Hamann, E., Weis, A. E. & Franks, S. J. Two decades of evolutionary changes in Brassica rapa in
response to fluctuations in precipitation and severe drought. Evolution 72, 2682-2696, doi:doi:10.1111/evo.13631 (2018).
3 Johnson, S. E., Hamann, E. & Franks, S. J. Rapid, parallel evolution of field mustard (Brassica rapa) under experimental drought. Evolution 76, 262-274, doi:https://doi.org/10.1111/evo.14413 (2022).
4 Franks, S. J., Hamann, E. & Weis, A. E. Using the resurrection approach to understand contemporary evolution in changing environments. Evolutionary Applications 11, 17-28, doi:10.1111/eva.12528 (2018).
5 Franks, S. J. et al. The resurrection initiative: storing ancestral genotypes to capture evolution in action. Bioscience 58, 870-873, doi:10.1641/B580913 (2008).
6 Etterson, J. R. et al. Project Baseline: An unprecedented resource to study plant evolution across space and time. American Journal of Botany 103, 164-173, doi:10.3732/ajb.1500313 (2016).
7 VanWallendael, A., Alvarez, M. & Franks, S. J. Patterns of population genomic diversity in the invasive Japanese knotweed species complex. American Journal of Botany 108, 857-868, doi:https://doi.org/10.1002/ajb2.1653 (2021).
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8 VanWallendael, A., Hamann, E. & Franks, S. J. Evidence for plasticity, but not local adaptation, in invasive Japanese knotweed (Reynoutria japonica) in North America. Evolutionary Ecology,
doi:10.1007/s10682-018-9942-7 (2018).