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Research Article

Contrasting environmental factors drive local adaptation at opposite ends of an environmental gradient in the yellow monkeyflower (Mimulus guttatus)

Damian Popovic

Department of Plant Biology, Michigan State University, East Lansing, MI, 48824 USA

Program in Ecology, Evolutionary Biology, and Behavior, Michigan State University, East Lansing, MI, 48824 USA

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David B. Lowry

Corresponding Author

E-mail address: dlowry@msu.edu

Department of Plant Biology, Michigan State University, East Lansing, MI, 48824 USA

Program in Ecology, Evolutionary Biology, and Behavior, Michigan State University, East Lansing, MI, 48824 USA

Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824 USA

Author for correspondence (e‐mail:

dlowry@msu.edu

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First published: 27 January 2020

Abstract

Premise

Identifying the environmental factors responsible for natural selection across different habitats is crucial for understanding the process of local adaptation in plants. Despite its importance, few studies have successfully isolated the environmental factors driving local adaptation in nature. In this study, we evaluated the agents of selection responsible for local adaptation of the monkeyflower Mimulus guttatus to California's coastal and inland habitats.

Methods

We implemented a manipulative reciprocal transplant experiment at coastal and inland sites, where we excluded aboveground stressors in an effort to elucidate their role in the evolution of local adaptation.

Results

Excluding aboveground stressors, most likely a combination of salt spray and herbivory, completely rescued inland annual plant fitness when transplanted to coastal habitat. The exclosures in inland habitat provided a benefit to the performance of coastal perennial plants. However, the exclosures are unlikely to provide much fitness benefit to the coastal plants at the inland site because of their general inability to flower in time to escape from the summer drought.

Conclusions

Our study demonstrates that a distinct set of selective agents (aboveground vs. belowground) are responsible for local adaptation at opposite ends of an environmental gradient.