Regional differences in rapid evolution during severe drought

Abstract

Climate change is increasing drought intensity, threatening biodiversity. Rapid evolution of drought adaptations might be required for population persistence, particularly in rear‐edge populations that may already be closer to physiological limits. Resurrection studies are a useful tool to assess adaptation to climate change, yet these studies rarely encompass the geographic range of a species. Here, we sampled 11 populations of scarlet monkeyflower (Mimulus cardinalis), collecting seeds across the plants’ northern, central, and southern range to track trait evolution from the lowest to the greatest moisture anomaly over a 7‐year period. We grew families generated from these populations across well‐watered and terminal drought treatments in a greenhouse and quantified five traits associated with dehydration escape and avoidance. When considering pre‐drought to peak‐drought phenotypes, we find that later date of flowering evolved across the range of M. cardinalis, suggesting a shift away from dehydration escape. Instead, traits consistent with dehydration avoidance evolved, with smaller and/or thicker leaves evolving in central and southern regions. The southern region also saw a loss of plasticity in these leaf traits by the peak of the drought, whereas flowering time remained plastic across all regions. This observed shift in traits from escape to avoidance occurred only in certain regions, revealing the importance of geographic context when examining adaptations to climate change.

Spatial variation in high temperature‐regulated gene expression predicts evolution of plasticity with climate change in the scarlet monkeyflower

“…Our findings are consistent with work showing rapid evolution of phenotypic plasticity in M . cardinalis following the period of recent drought and warming (Anstett et al, 2021), but contrast with other work in this system documenting limited evolutionary responses in thermal performance traits (Wooliver et al, 2020) and flowering time (Vtipil & Sheth, 2020). Together, these resurrection studies indicate that evolutionary responses in plasticity, rather than in mean trait values, may be more rapid in the context of recent climate change.…”

“…showing rapid evolution of phenotypic plasticity in M. cardinalis following the period of recent drought and warming (Anstett et al, 2021), but contrast with other work in this system documenting limited evolutionary responses in thermal performance traits and flowering time (Vtipil & Sheth, 2020). Together, Our results also validate the use of spatial data for predicting plant responses to global warming when chronological observations are lacking (Blois et al, 2013).…”

“…The scarlet monkeyflower ( Mimulus cardinalis ; Phrymaceae) (Fraga, 2018; Lowry et al, 2019) is a great model to study the role of plasticity in climate adaptation across both space and time, and as such can be used to assess whether evolutionary changes in response to spatial heterogeneity can predict changes that occur with climate change over time. This species has a fully sequenced genome (http://www.mimubase.org) and spans a wide latitudinal and temperature range across western North America, with populations experiencing recent temporal changes in both the yearly mean and variance of temperature and water availability (Anstett et al, 2021; Sheth & Angert, 2016; Vtipil & Sheth, 2020; Wooliver et al, 2020). A comparison of 12 contemporaneous M .…”

“…A study examining the evolution of plasticity in phenological and leaf traits in response to drought showed that populations across the range of M . cardinalis maintained phenological plasticity, and southern‐edge populations evolved decreased plasticity in leaf traits over a 7‐year period (Anstett et al, 2021). This finding highlights the potential for rapid evolutionary shifts in plasticity in response to environmental change.…”

Rules of Plant Species Ranges: Applications for Conservation Strategies

“…Besides directly measuring QGV across species ranges, other methods to quantify differences in adaptive potential such as artificial selection and resurrection studies-in which prior generations are compared to contemporary populations for their trait values-are useful for contrasting historical patterns with contemporary patterns to understand how populations are responding to climate change. Recent plant resurrection studies have captured varying phenological change in response to climate change and illustrate that some degree of rapid adaptation is possible for many plant species (Franks et al, 2018;Dickman et al, 2019;Vtipil and Sheth, 2020;Wooliver et al, 2020;Anstett et al, 2021;Kooyers et al, 2021).…”