Rangewide responses to an extreme heat event in Mimulus cardinalis
Data files
Oct 29, 2025 version files 190.39 KB
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Albano_et_al_2025_AJB_Data.csv
145.52 KB
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Albano_et_al_2025_AJB_Script.R
41.10 KB
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README.md
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Jan 12, 2026 version files 191.28 KB
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Albano_et_al_2026_AJB_Data.csv
146.11 KB
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Albano_et_al_2026_AJB_Script.R
41.13 KB
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README.md
4.04 KB
Abstract
Premise: Extreme events are an understudied aspect of ongoing anthropogenic climate change that could play a disproportionate role in the threat that rapid environmental shifts pose to natural populations.
Methods: We exposed plants originating from seeds that were harvested before (ancestors) and after (descendants) multiple extreme heat events from six populations across the range of Mimulus cardinalis (Phyrmaceae) to a short‐term heat‐wave treatment in controlled growth chamber environments. We assessed physiological, performance, and functional responses (stomatal conductance, leaf temperature deficit, photosystem II efficiency, relative growth rate, specific leaf area, and leaf dry matter content) to the heat‐wave treatment, along with evolutionary responses (differences between ancestors and descendants) of M. cardinalis populations to the recent natural extreme heat event.
Results: Plants in the heat‐wave treatment increased their overall performance, and the magnitude of increase was generally greatest among trailing‐edge populations. Despite limited overall trait differences between ancestors and descendants, there was some evidence of divergent evolutionary responses among regions to the natural extreme heat event. However, we did not find evidence of adaptive evolution that affected how M. cardinalis populations responded to the heat‐wave treatment.
Conclusions: These results demonstrate that many M. cardinalis populations may reside in environments that are below their optimum average temperature, revealing potential resiliency to future warming. However, limited evolutionary responses in M. cardinalis to the recent extreme heat wave could still indicate potential for future vulnerability to extreme climate events of increased intensity, frequency, and duration.
Readme file associated with the paper Albano et al., American Journal of Botany (accepted October 20, 2025, to be published in February, 2026).
Title: Range-wide responses to an extreme heat event in Mimulus cardinalis
In this paper, we perform a resurrection experiment, exposing Mimulus cardinalis to a heat-wave treatment in growth chamber environments. M. cardinalis individuals were sourced from six populations across its range (two leading-edge, two range-center, two trailing-edge) and within each population, seeds were harvested in 2010 (ancestors) and 2017 (descendants) which were time periods selected before and after a natural multi-year heat-wave event in western North America. This design allows for investigation of physiological, performance, and functional trait responses to the heat-wave treatment for each population, along with investigation of evolutionary responses to the natural heat-wave event that could affect how plants respond to the heat-wave treatment. This experiment addressed two main objectives: (1) quantify responses in plant physiological, performance, and functional traits to a heat-wave treatment and determine if those responses varied among populations from across the range of M. cardinalis, and (2) characterize differences in response to a heat-wave treatment between 2010 ancestors and 2017 descendants, indicative of an evolutionary response to the recent heat and drought event experienced by natural M. cardinalis populations.
The script to analyze the data required to address these objectives can be found in Albano_et_al_2026_AJB_Script.R, while the data itself can be found in Albano_et_al_2026_AJB_Data.csv, which contains the following columns:
- Cohort: The category of year at which an individual was harvested. Ancestor (2010) or Descendant (2017)
- Region: The region from which an individual was harvested, essentially a combination of two populations from each region. N (leading-edge), C (range-center), or S (trailing-edge)
- Heat: The heat-wave treatment performed on each individual. Control or Heat wave
- Cross_ID: The cross identifier used to separate individuals based on their parentage through the creation of a refresher generation prior to the initiation of the experiment
- Time1: A unitless scaled measure of time of day, constructed by combining individual hour, minute, and second variables.
- Time2: The Time1 variable converted to a factor variable (necessary for autocorrelation models)
- Date: The date on which physiological traits (gsw, Tdiff, and PhiPS2) were measured for each individual. Format: MM/DD/YYYY
- Population: The population from which an individual was harvested. N1 (leading-edge population #1), N2 (leading-edge 2), C1 (range-center 1), C2 (range-center 2), S1 (trailing-edge 1), or S2 (trailing-edge 2)
- gsw: Stomatal conductance (of water vapor) measurement from one leaf of each individual plant. Units: mmol m-2 s-1
- gsw_Pred: Predicted stomatal conductance (of water vapor) measurement from each control individual if it was to be exposed to the heat-wave treatment, based solely on the physical effects of temperature increase. Units: mmol m-2 s-1
- Tdiff: Leaf temperature at the moment gsw was assessed minus air temperature in the growth chamber. Units: °C
- PhiPS2: Unitless photosystem II efficiency (ΦPSII) for each individual plant
- leaf_RGR: The relative growth rate of each individual plant, based on the number of leaves present prior to and after the experiment. Units: leaves leaves-1 day-1
- SLA: The specific leaf area of one leaf on each individual plant. Units: cm2 g-1
- LDMC: The leaf dry matter content of one leaf on each individual plant. Units: mg g^-1
*NA values in the leaf_RGR, SLA, and LDMC columns represent individuals that were too small and/or unhealthy for this data to be collected.
**All heat-wave plants ("Heat wave" in the "Heat" column) are recorded as NA in the gsw_Pred column because the predicted stomatal conductance increase measurement only applies to "Control" plants
Changes after Oct 29, 2025: Minor changes were made to figure formatting at the proofing stage, which are now reflected in the updated Script and Data files (the most prominent example being a change in wording from "heatwave" to "heat wave" to reflect this requested change throughout the manuscript by the journal). Both files were also updated to reflect the 2026 date of publication as opposed to the 2025 date of acceptance. The beginning of the script was also updated to remove some unnecessary variables and allow for a more seamless reading in of the data with minimal opportunity for confusion.