Seeds collected during a historic western U.S. drought produced plants with higher fitness and faster timing at a high-elevation garden.
Researchers grew seeds of the annual plant Erythranthe laciniata collected before the drought and at its height. They tested nine populations in three gardens at low, central and high elevations, recording flowering timing and flower production as measures of lifetime fitness.
Plants from the drought generation had higher fitness and developed faster timing at the high-elevation garden. The researchers also found climate adaptation at the low and high gardens. At the central garden, low-elevation populations outperformed central populations, a pattern the researchers say may indicate an adaptive lag as the climate changes.
Where adaptation helped
The drought generation of Erythranthe laciniata had higher fitness at the high-elevation garden and evolved faster phenology—the timing of key life stages, such as flowering. The study also detected climate adaptation at the low- and high-elevation gardens.
At the central garden, low-elevation populations outperformed central populations. The researchers interpret this as evidence that some populations may not yet match contemporary climate conditions. Overall, the results indicate rapid adaptation that was beneficial mainly at the leading edge of the species’ range. The experiment included nine populations, more than 2,100 plants, and three common gardens.
Why range position matters
The findings suggest that rapid evolution can help a plant population cope with an extreme climate event, particularly where the species’ range is advancing into new conditions. They also show that adaptation may not benefit all parts of a species’ range equally.
The low fitness observed at lower elevations may foreshadow range contraction if climate change continues to produce conditions that those populations cannot match. The results therefore point to both the potential and the limits of rapid adaptation.
Evidence and caveats
The evidence comes from a common-garden experiment using seeds collected before and during the 2012–2016 drought. Growing populations under shared conditions allowed the researchers to compare inherited differences in flowering timing and flower production across nine populations and three elevations. The experiment was conducted in 2021, a year with relatively low precipitation and high temperatures.
The study examined one endemic annual plant and one field experiment, so the findings do not establish how other species or populations will respond to future droughts. The measured outcomes were phenology and flower production as indicators of lifetime fitness; longer-term changes in population size and range were not directly measured.
// Source
Journal of Evolutionary Biology · 2026 · DOI: 10.1093/jeb/voag088
Authors: Lillie K. Pennington, Jason P. Sexton
Institutions: University of Georgia, University of California, Merced
