Long-term studies since 1929 have revealed important information about the evolution of barley, showing its adaptation to different environments and the significant influence of natural selection. This work highlights the limitations of evolutionary selection and highlights the need for further research to increase yields.

Using one of the world’s oldest biological experiments, which began in 1929, researchers have discovered how barley, a staple crop, is affected by agricultural pressures and changing natural environments. These results highlight the importance of long-term studies to understand the dynamics of adaptive evolution.

The survival of cultivated plants after settling in different environments is a classic example of rapid adaptive evolution. For example, barley, a major Neolithic crop, spread widely after its domestication 10,000 years ago and became an important food source for humans and animals in Europe, Asia, and North Africa within just a few thousand generations. This rapid expansion and cultivation subjected plants to strong selective pressures, including artificial selection for desirable traits and natural selection, that forced them to adapt to a variety of new environments.

Genetic results of the Composite Barley Cross II experiment

Although previous studies of early barley cultivars have revealed some elements of the plant’s population genetic history and mapped genetic loci that contributed to its spread, the speed and overall dynamics of these processes are difficult to determine without direct observation. Jacob Landis and colleagues have observed the process of local adaptation in barley over the course of nearly a century using one of the world’s oldest and longest-running evolutionary experiments, the Barley Compound Cross II (CCII). The CCII is a multigenerational common garden experiment that began in 1929 to adapt a population of 28 genetically diverse barley cultivars to the environmental conditions of Davis, California.

Although the experiment began decades ago with thousands of genotypes, Landis et al. They show that natural selection has significantly reduced this diversity, eliminating almost all of the founding genotypes and leading to the dominance of a single clonal lineage that accounts for most of the population. This change occurred rapidly, and by generation 50, a clonal lineage was established. The results suggest that this successful lineage consists mainly of alleles originating in Mediterranean environments, such as Davis’s. In addition, the authors show that genes targeted by selection point to an important role for climate during adaptation, including strong selection on reproductive timing.

“In this experiment, we found strong evidence that local adaptation dominated evolution. However, despite rapid early yield increases in CCII, the evolutionary approach to breeding has not kept pace with the gains seen with pedigree-based breeding methods,” Landis wrote. etc. “Understanding why the most competitive genotypes produced during local adaptation do not necessarily have the highest yields will be of great interest in the future.”