All species must adapt to their environments, and even distantly related species may experience similar ecological pressures. Plants are strongly impacted by their abiotic environment, with the ranges of many species spanning both hot and cold or wet and dry regions. By sequencing the genomes of many individuals sampled across a range of environmental conditions, it is possible to search for signatures of natural selection, however it can be notoriously difficult to parse this from the noise of genetic drift. One promising approach is to make comparisons across multiple lineages that are independently evolving in response to the same stress, as genetic drift would be unlikely to drive a strong pattern repeatedly in the same gene. Here, I explore how studies of repeated adaptation can provide insights into how evolution works and identify interesting candidate genes for future study. I begin by reviewing a study across very broad evolutionary timescales, comparing signatures of adaptation to climate across 25 distantly related plant species. We find many genes driving adaptation that are well-known for their role in abiotic stress responses, but also a large number with little known function. I then focus in on patterns of repeated adaptation in a pair of conifer tree species that have been hybridizing throughout Western Canada, and explore how adaptation to varying environmental conditions found in their mountainous habitat is shaping patterns in the genome. In all cases, the genome provides intriguing clues about how adaptation works, but ultimately, we will need to also connect these patterns with the phenotype to have a more complete picture of evolution.

Yeaman, S. Evolution of polygenic traits under global vs local adaptation. Genetics 220, iyab134 (2022)

Yeaman, S. et al. Convergent local adaptation to climate in distantly related conifers. Science 353, 1431–1433 (2016)

Nocchi, G., Whiting, J. R. & Yeaman, S. Repeated global adaptation across plant species. Proc. Natl. Acad. Sci. U.S.A. 121, e2406832121(2024)

Whiting, J. R. et al. The genetic architecture of repeated local adaptation to climate in distantly related plants. Nat Ecol Evol 8, 1933–1947 (2024)

Bohutínská, M. & Peichel, C. L. Divergence time shapes gene reuse during repeated adaptation. Trends in Ecology & Evolution 39, 396–407 (2024)

東京大学大学院理学系研究科・生物科学専攻・植物進化生態学研究室