Moisés Expósito-Alonso started studying genetics because he was interested in “how a plant decides what to do without a brain.” Then, as an intern at Doñana National Park in Spain during his undergraduate, he learned that plant decisions are genetically controlled. “You can tell a lot about an organism based on its genome. That was the idea that fascinated me and it’s how I got into genetics,” says Expósito-Alonso, who is currently an Assistant Professor of Integrative Biology at University of California, Berkeley, a Freeman Hrabowski Scholar at Howard Hughes Medical Institute, and the recipient of the 2026 GSA Early Career Medal. 

Before he started his PhD research at the Max Planck Institute for Biology Tübingen, Expósito-Alonso already knew what he wanted to work on. He brought his ideas to Detlef Weigel, Director at the institute. Weigel, who became his PhD advisor, described the project as “much more ambitious than I could have imagined,” adding that Expósito-Alonso had “big ideas [and] big plans.”

This ambitious project led Expósito-Alonso to orchestrate a multi-site, years-long experiment, planting thousands of crops and using experimental evolution approaches, to observe how plant genomes evolve when faced with rapid environmental changes like climate change.

At first Expósito-Alonso simulated drought conditions in a greenhouse full of Arabidopsis thaliana plants. Through genome-wide association studies, he found that drought resistance genes came from two geographies: North Africa or near the Arctic. He expanded this study to real-world conditions in Spain’s dry, hot climate and Germany’s more moderate climate. Weigel, who saw Expósito-Alonso easily persuade the entire lab to participate in this experiment, describes him as a “natural role model who leads by example.” The team soon planted 25,000 plants from over 500 A. thaliana genotypes spanning both locations and found that traits like drought resistance come at a cost to other aspects of growth and fitness. This study also revealed that many genotypes have lower fitness as temperatures rise, suggesting that some A. thaliana populations are at evolutionary risk.

However, Expósito-Alonso had a bigger vision. He thought, “If we are ever going to more comprehensively understand evolution to climates, we need dozens of locations and we need to do this for many years.” “The difficulty was the implementation,” he says. Towards the end of his PhD program, he teamed up with Niek Scheepens and François Vasseur who were at the University of Tübingen and at Max Planck Institute, respectively, at the time to form the Genomics of Rapid Evolution in Novel Environments Project (GrENE-net). They recruited scientists from universities across Europe, the Levant, and North America so they could test genetic evolution in multiple climate regions. Each scientist started with planting the same set of seeds from over 200 A. thaliana strains. Each year during the flowering season, the researchers harvested one flower from each plant and sent it back to the team for sequencing. The project continued for five years allowing them to see what genetic variants became enriched or extinguished over time in each location. 

In the first three years of the project, some sites lost entire populations because the plants couldn’t tolerate the conditions, and other locations saw population rebounds after initial decline. The work both highlights the capacity for species to adapt to future climate change and shows the risk of species extinction with population bottlenecks and genetic diversity loss brought on by rapid environmental changes. 

To better understand how human activity is driving genetic diversity loss, which could spiral in further extinction risk of species, Expósito-Alonso published the first global estimates of genetic diversity loss in 2022. He found that anthropogenic changes have already reduced global genetic diversity by 10%, with some species already losing 90% of genetic diversity. These findings suggest that the United Nations’ target for protecting 90% of global genetic diversity by 2030 may already be out of reach. This work on genetic diversity loss led Expósito-Alonso to serve as a delegate in 2022 at the United Nations Convention on Biological Diversity.

Beyond research and global policy, Expósito-Alonso has built a reputation leading a diverse, interdisciplinary team. Lauren Gillespie, incoming assistant professor at University of Michigan, was his first graduate student. She started in the lab right at the beginning of the COVID-19 pandemic. “Moi did a really good job of trying to build community despite the challenges of the pandemic,” she reflects, thinking back on the weekly happy hours, science talks, and a virtual Halloween event that Expósito-Alonso organized for the lab. 

Expósito-Alonso is a mentor at the crossroads of computer science, evolutionary genetics, ecology, and plant biology and has built his lab, gathering experts from multiple disciplines. For Gillespie, who came from a computer science background, the move to an eco-evo lab was not “an easy transition” but she credited Expósito-Alonso’s guidance for quickly getting her up to speed. “There were postdocs with computer science backgrounds, there were postdocs with plant microbiology background, and folks coming from botany and bioinformatics,” she says. “It was really cool that he was able to steer all of those different backgrounds.” In addition to mentoring, Expósito-Alonso has led efforts in supporting minority students in the University of California and has expanded experiential course work to learn about plant genetics in the wild.

“He’s a very authentic individual,” says Weigel. “He is motivated by the desire to help a world that is rapidly changing.”

Please join us in congratulating Moisés Expósito-Alonso on receiving the 2026 GSA Early Career Medal for his contributions to modern genetics.

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