Interactions between maternal provisioning and natural selection on seed mass fluctuate across heat waves

This repository contains two datasets from Gaspard et al. 2026. 
FileA corresponds to seed and germination properties collected from
crosses in a resurrection experiment, while FileB corresponds to seed and
germination properties from a growth chamber experiment manipulating
drought stress to simulate natural heat waves. Below is the abstract from
the corresponding manuscript. Premise of study: Changing climates are
leading to more frequent and severe heatwaves, potentially threatening
plant populations. Both acclimation to stress and selection for
heat-resistant phenotypes occur during heatwaves. However, plastic
responses and selection do not necessarily interact cohesively – even
producing responses in opposite directions, a phenomenon termed counter
gradient variation – that could cause maladaptation in future generations.
  Methods: Here we examine patterns of maternal provisioning and
natural selection on seed mass and germination characteristics following
two natural heatwaves across twelve annual Mimulus guttatus populations.
We then recreate heatwave events occurring early and late within a growing
season using a manipulative experiment to determine the reproducibility of
our results.   Key Results: There was selection for greater seed
mass during the year of the early season heat wave and seed mass remained
high through the late-season heatwave. However, field observations of seed
mass only reflect this pattern during the early season heatwave, and
plants that experienced a late season heatwave had small seeds that
germinated later. This incongruency is indicative of counter gradient
variation with decreased maternal provisioning coinciding with selection
for larger seeds.   Conclusions: Our results demonstrate that the
relationship between selection and maternal provisioning fluctuates
between years. Such counter gradient variation may be adaptive if smaller
seeds are more likely to persist in the seed bank or if climatic
conditions exhibit negative temporal autocorrelation. However, counter
gradient variation could also constrain the potential of natural selection
and lead to high mortality in heatwaves during successive years.​