In their fight against climate change, west coast wildflower species like the scarlet monkeyflower have found ways to endure increasing dry spells.
By Lily Roby, Courthouse News Service
Since the turn of the century, California has been experiencing its worst drought in more than 1,000 years.
And in the face of climate change that can drive species to extinction, some wildflower populations are now learning how to endure the crisis through evolution.
In a new study published Thursday in the journal Science, researchers detail their discovery that plant populations can undergo evolutionary rescue, a process in which rapid genetic adaptation allows a declining population to rebound rather than die out. The process, although likely rare, illuminates how species are coping in a warming world with severe climate extremes.
A colorful perennial with red or orange petals and vibrantly green foliage, the scarlet monkeyflower is a native plant found across western North America. The study’s researchers focused on the wildflower for over eight years, monitoring 55 different populations up and down the west coast and even managing to capture the plant’s reactions to California’s most extreme four-year drought period that began in 2012.
Daniel N. Anstett, an evolutionary ecologist who works with various universities including Cornell University, led the research team in conducting whole-genome sequencing in addition to long-term tracking of plant populations. The methodical approach allowed the researchers to track demographic changes, such as population declines and recoveries, and shifts in genetic variants linked to climate tolerance.
While some populations of the plant declined sharply and even died off during the four-year drought, others recovered and came back with force after the drought ended. Yet genome sequencing offered a new, shocking perspective into the success of the monkeyflower — the populations that survived did so thanks to rapid genetic changes.
Some populations of the plant had developed genetic variants over only a few generations that made dry environments easier for them to handle. When extreme drought conditions struck, natural selection favored the variants that helped plants survive with less water, allowing those genetic versions to spread quickly through the population.
Populations that evolved greater drought tolerance during the dry period were more likely to rebound in size once conditions improved. In other words, the same genetic changes that helped plants survive the drought also helped predict which populations would recover most successfully afterward.
Such findings are important for understanding how species may respond to climate change. Extreme environmental events such as prolonged droughts, heat waves or floods are becoming more frequent and severe in many regions. These conditions can push populations toward collapse, but evolutionary rescue offers a potential pathway to recovery.
However, evolutionary rescue can’t be relied on universally as not all wildflower populations survived the megadrought. Some monkeyflowers still became locally extinct in certain areas of California in response to the harsh conditions.
But just understanding evolutionary rescue and when or where it occurs could be a game changer for conservation planning. As the climate grows more intense, scientists will likely need to identify which species have the capacity to adapt and which are unable to recover without intervention.
“The challenge going forward is to identify when evolutionary rescue is possible (and) when it is not,” wrote researchers Mark Urban and Laurinne Balstad in a related perspective paper. Those that can’t rescue themselves will likely need intervention to survive our warming world.
