UC Berkeley-Led Global Experiment Identifies 'Evolutionary Breaking Point' for Plants Facing Extreme Climate Stress

UC Berkeley researchers tracked Arabidopsis evolution at 30 global sites, finding that while plants can adapt quickly, extreme heat can trigger an evolutionary breaking point.

By: AXL Media

Published: Mar 27, 2026, 7:55 AM EDT

Source: Information for this report was sourced from University of California - Berkeley

A Global Network for Real-Time Evolutionary Tracking

Biologists have long debated whether plant species can evolve fast enough to survive a rapidly warming planet. To answer this, Moisés Expósito-Alonso, an assistant professor of integrative biology at UC Berkeley, coordinated the Genomics of rapid Evolution to Novel Environment (GrENE) network. This consortium established 360 experimental plots of Arabidopsis thaliana across diverse climates—from the snowy Kitzbühel Alps to the arid Negev Desert. Unlike traditional, isolated studies, this massive, synchronized effort allowed researchers to observe evolutionary selection pressures acting simultaneously across three continents, providing a quantitative baseline for how quickly flora can adapt to shifting environmental boundaries.

Pinpointing Adaptive Gene Variants

By sequencing the whole genomes of over 70,000 surviving plants, the research team identified millions of genetic alterations that signify active adaptation. The study, published in Science, found that in 24 of the 30 locations, evolution was highly repeatable and predictable. Similar climates triggered similar genetic shifts, particularly in genes responsible for heat stress sensing and the timing of spring flowering. These findings suggest that when a population possesses high internal genetic diversity, natural selection can drive significant genomic changes in as little as three to five years, effectively "re-using" pre-existing genetic variations to meet new environmental challenges.

The Tipping Point: Evolution vs. Genetic Drift

The most critical finding of the experiment concerns the limits of this rapid adaptation. In the warmest environments—those most representative of future global warming scenarios—many populations failed to evolve successfully. Instead of the organized genetic shifts seen in surviving groups, these failing populations exhibited "chaotic" or random genetic changes, a phenomenon known as genetic drift. Expósito-Alonso explained that extreme heat often limits populations to such small sizes that they lose the ability to undergo effective natural selection. Once a population passes this "evolutionary breaking point," extinction becomes inevitable regardless of its initial genetic diversity.