Study highlights the importance of biodiversity for the survival of rare plants and their ability to adapt to climate change
- Adaptation to climatic conditions: Plant populations adapt to local conditions in most climate zones. These adaptations involve genes that influence drought tolerance and flowering time. With sufficient genetic diversity, evolution can occur within three to five years.
- Challenges at extreme locations: Populations in extremely hot and dry locations often died out within three years. Significant genetic variation meant that not all populations evolved in the same direction.
- Call for biodiversity: The study emphasizes the importance of genetic diversity for the survival of rare plants and for coping with climate change. Preserving biodiversity is crucial for the adaptability of species.
Evolution in Real Time: An international research team has studied the evolution of the thale cress Arabidopsis thaliana over a ten-year period at 30 locations worldwide. Their findings show that genetic diversity is crucial for the survival of plant populations.
In autumn 2017, the three researchers assembled hundreds of plastic tubes with seed mixtures produced at the Max Planck Institute. The seeds came from over two hundred Arabidopsis thaliana lines collected from around the world, whose genetic variation had been characterized at the Max Planck Institute. The tubes were shipped to 30 sites across Western and Northern Europe, the Mediterranean region, and the United States.
At each location, biologists from the global network sowed the seeds in twelve plots of roughly a quarter of a square meter each, establishing twelve distinct populations. These populations self-perpetuated through seed production, and for up to five years researchers monitored plant growth and performance while collecting tissue samples annually for genetic analysis - all with the shared aim of tracing how plants evolve to meet the demands of highly diverse environments.
Adaptation to local conditions
Genetic analysis of plant samples from the first three years, carried out by the Expósito-Alonso team, showed that populations in most climate zones survived and adapted to local conditions. This was evident in millions of changes spread across the genome. Crucially, many of these genomic shifts were statistically consistent across all twelve populations at a given site, and sites with similar climates displayed similar genetic changes - particularly in genes associated with traits such as drought tolerance and flowering time.
"Our big questions were, 'At what speed does evolution go?' and 'When will it not go?'" says Moisés Expósito-Alonso. "What we could show is that this tempo, if given enough genetic diversity, can be three, four, or five years. For the first time, we can directly observe how certain DNA variants - adaptive variants - take over in populations as evolution unfolds." Detlef Weigel, Director of the Department of Molecular Biology at the Max Planck Institute for Biology Tübingen, adds: "In our previous work, we studied how quickly new genetic variation arises through mutation. Now we have a first sense of how quickly those mutations can take over a population."
Extinction at extreme sites
Not all populations fared well, however. Those at particularly hot and dry sites largely went extinct within three years, leaving their plots barren. Genome analyses revealed that chaotic genetic fluctuations had preceded these extinctions, with the twelve populations failing to evolve in a consistent direction. Evolutionary ecologist Niek Scheepens from Goethe University Frankfurt draws a broader lesson from these findings: "With this experiment, we can watch evolution unfold almost in real time. It demonstrates that rapid evolutionary adaptation is possible - but only when sufficient genetic diversity is present. Rare plant species with small populations and low genetic diversity are therefore poorly equipped to cope with environmental change, including climate change. Ultimately, our experiment is a compelling argument for preserving biodiversity : diversity ensures survival."
For Weigel, the study marks a deeply satisfying milestone: "I could not have been happier to see an experiment that lab members conceived of ten years ago come to such a spectacular conclusion - and it is above all’a testament to the scientific vision and scientific leadership of Moisés Expósito-Alonso, whose enormous talent was already apparent when he was a graduate student."
Genomics of Rapid Evolution in Novel Environments
The network "Genomics of Rapid Evolution in Novel Environments" (GrENE-net) was founded in 2016 by two scientists working in the laboratory of Detlef Weigel, Director of the Department of Molecular Biology at the Max Planck Institute for Biology Tübingen. The researchers were Moisés Expósito-Alonso, then a graduate student at the Institute and now a Professor at the University of California, Berkeley, and François Vasseur, then a postdoctoral researcher and now a scientist at the Centre d'Écologie Fonctionnelle et Évolutive in Montpellier. They collaborated with Niek Scheepens, then a professor at the University of Tübingen and now Professor of Plant Evolutionary Ecology at Goethe University Frankfurt.
