Collaborative Research: ORCC: Harnessing Adaptive Variation in Drought Resistance Strategies to Manage Populations Under Climate Change

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Preserving biological diversity in the face of climate change is a major societal challenge, and land managers face daily decisions about how to do so as they strive to sustain natural resources. Climate change is increasing average temperatures and also changing how often and how intensely extreme events like severe droughts occur. Extreme events are particularly challenging for organisms with limited movement like plants, potentially causing enduring losses of diversity or even local extinctions. Management and conservation actions that take predicted future environments into account are necessary, but there is little consensus on what these actions should be and what biological principles should guide them. This challenge exists in part because studying what traits allow plants to withstand these extreme climate events is difficult; extreme droughts occur unpredictably, yet data or experimental resources must be obtained beforehand to assess the event’s impact. The proposed research will take advantage of a decade of collections of the common monkeyflower, Mimulus guttatus, made before, during, and after a severe, multi-year drought experienced in the 2010s in the Western US. Through studying what genetic variants and characteristics have helped adapt different populations to long-term differences in moisture among sites and also to this severe contemporary event, the proposed research will reveal strategies that may allow populations to remain resilient in future climates. These predictions will be tested in field studies. Through workshops with land managers, the project design will be informed by relevant stakeholders, and the results will subsequently inform their decisions.The proposed research will address this overarching question: what genetic and organismal adjustments to drought resistance strategies will promote local population resilience to changing climates? Annual populations of M. guttatus, are widespread but patchily distributed across a landscape over which the seasonal timing and severity of drought stress is highly variable. Although M. guttatus populations show multiple genetic and organismal signatures of adaptation to spatial variation in aridity, recent work has found they are becoming locally maladapted as climate change causes increasingly drastic disruptions to historical drought regimes. The project will intensively characterize how genetic variation acts through regulatory networks to adaptively tune organismal strategies to local conditions and ask whether the varied eco-evolutionary processes that unfolded during the 2010s Western US drought are explained by local variation in historical drought intensity, local standing genetic variation, or seed bank dynamics. Specifically, population genomic analyses and in-depth resurrection experiments will assess how genes and morphological, transcriptomic, and ecophysiological traits evolved during this severe drought event. How drought-associated alleles adaptively adjust these traits will be tested functionally by gene editing, and manipulative field experiments will evaluate how these genetic and organismal factors enhance fitness under current and predicted future drought regimes. All experiments will be structured around a common set of genotypes, and the resulting synergy will enable construction and validation of predictive frameworks for inclusion of genetic and organismal data into assisted gene flow practices as a means to promote population resilience to climate change and inform critical conservation decisions.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.