The mountain jewelflower inhabits a wide swath of California and Oregon, from summer-scorched foothills to high mountains where snow falls during winter. But it is already suffering from climate change, with plants in the mountains struggling to survive both summers and winters, according to a study from the University of California, Davis.
“Evolutionarily, it isn’t keeping up with changes in the environment,” said lead author Brandie Quarles-Chidyagwai, a UC Davis postdoctoral scholar in the Department of Plant Biology.
Different populations of this species evolved over millennia to fit California’s diverse environments. With climate change, those adaptations may no longer match local conditions, potentially threatening the mountain jewelflower (Streptanthus tortuosus) — especially in the high mountains.
However, the study, published in the Journal of Ecology, also provides hope. It found that plants from lower elevations may have traits that match new mountain conditions.
“It suggests potential conservation strategies that might help these plants,” Quarles-Chidyagwai said.
A strategy called assisted gene flow could reshuffle the plant’s gene variants into new combinations that better match the new climates. The same strategy could also help many other plant species.
Changing climates in the western U.S.
As temperatures warm, California has seen frequent droughts, with reduced snowpack and earlier snowmelt in the Sierra Nevada. Conditions at high elevations have become more like what low elevations experienced in the past. This has shifted the timing of growing seasons and altered the conditions that plants experience during them.
The mountain jewelflower is already falling behind these changes, according to results previously published research by UC Davis Professors Jenny Gremer and Julin Maloof. Their experiments on low-elevation plants suggested that if the growing seasons shift, the plants’ seeds are less likely to sprout — and the plants that do emerge produce fewer seeds.
“We know that shifting seasons are already having negative effects on low-elevation populations,” Gremer said. “We also wanted to find out how other populations are doing.”
Quarles-Chidyagwai worked with Gremer and Maloof to examine how climate change is affecting one especially vulnerable part of the species: mountain jeweflowers adapted to cold, high-elevation landscapes.
At a site high in the Sierra, they planted seedlings from various regions of California — including both high-elevation areas and lower, warmer, drier areas. If the high-elevation plants fared better than the others, it would suggest that even after a century of climate change, they were still well-adapted to their home range.
But the results showed something very different.
During the first summer, the high-elevation plants survived and produced seeds at lower rates than the lowland plants did. Surprisingly, when Quarles-Chidyagwai returned the following June, she found that the high-elevation plants had once again fared worse, surviving the winter at lower rates than the plants from lower, warmer areas.
This suggested that these high-elevation plants were no longer well-adapted to their environment, suffering not only through a hot, dry summer, but also through a winter when the snow was unusually thin, providing the plants with less protection.
That bodes poorly for the future, said Quarles-Chidyagwai: “We’re going to see more winters with less consistent snowpack.”
Mixing genes to meet the moment
The experiment also yielded a hopeful result.
Despite suffering through the first summer and winter, high-elevation plants survived their second growing season at higher rates than the other plants, allowing them to produce more seeds across their lifetimes.
This suggested that despite climate warming, the high-elevation plants are still well-adapted to at least some aspects of their mountain environment. More importantly, it indicated that the species possesses a set of gene variants that may help it survive newly emerging climates. Those useful gene variants just happen to be scattered across different populations of the plant inhabiting different parts of California.
Quarles-Chidyagwai, Maloof and Gremer are now doing assisted gene flow experiments to combine those gene variants into a single population of plants.
By interbreeding mountain jewelflowers from high and low elevations, “we can hopefully get the ideal combination of genes and create an ideal plant” for these new climates, Quarles-Chidyagwai said.
Insights gleaned from the mountain jewelflower suggest that assisted gene flow might also help other plant species adapt to changing climates.
“When you have these broadly distributed species, that can be useful for conservation,” Quarles-Chidyagwai said.
This research is funded by the National Science Foundation and the National Institute of Food and Agriculture. It used advanced scientific facilities at UC Davis, including the Controlled Environment Facility and research greenhouses.
Additional co-authors include Sarah Ashlock and Johanna Schmitt from UC Davis.