A study on the scarlet monkeyflower (Mimulus cardinalis) shows it recovered from a severe drought in California via rapid evolution, marking the first observed case of evolutionary rescue in the wild. Researchers led by Daniel Anstett at Cornell University tracked the plant's response to the 2012-2015 megadrought. While this offers hope for species facing climate change, experts note limitations for long-term adaptation.
The scarlet monkeyflower, a water-dependent plant native to streams, faced severe challenges during California's megadrought from 2012 to 2015. Daniel Anstett and his team at Cornell University began monitoring populations across the plant's range in 2010, collecting annual data on performance and DNA samples.
Three local populations perished due to the drought, which Anstett described as lethal: “If you were to put one in a pot and not water it for a few days, it would just die.” Surviving groups, however, evolved drought tolerance within three years. Genetic analysis revealed mutations in genome regions associated with climate adaptations, enabling these populations to rebound quickest post-drought.
This phenomenon, termed evolutionary rescue, involves a species averting decline through swift genetic changes. Anstett's work, published in Science (DOI: 10.1126/science.adu0995), fulfills three criteria: documenting population decline from a threat, genetic adaptation, and recovery linked to those changes. Previous examples, such as Galapagos finches adapting to drought or Tasmanian devils responding to cancer, showed evolution but not full recovery ties.
Andrew Storfer at Washington State University, who researches Tasmanian devils, confirmed: “To be clear, we’ve demonstrated rapid evolution in Tasmanian devils. But with the evidence in hand, we cannot link it to demographic recovery.”
Historical climate shifts over 500 million years demonstrate species' past adaptations, including to hotter periods with crocodiles in the Arctic. Yet, current warming—potentially over 4°C by century's end—occurs far faster than events like the Paleocene-Eocene thermal maximum, which took 20,000 years for 5-8°C rise.
Anstett views this as encouraging, noting many decline predictions overlook evolution. However, a single drought represents weather, not sustained climate change. Future extremes could overwhelm adaptations, and repeated hits reduce genetic diversity, hindering further evolution—especially for long-lived species with extended generations.
