Abstract
Through the lens of evolution, climate change is an agent of natural selection that forces populations to change and adapt, or face extinction. Current assessments of the risk of biodiversity associated with climate change1, however, do not typically take into account the genetic makeup of populations and how natural selection impacts it2. We made use of the extensive genome information in Arabidopsis thaliana and measured how rainfall-manipulation affected the fitness of 517 natural lines grown in Spain and Germany. This allowed us to directly infer selection along the genome3. Natural selection was particularly strong in the hot-dry Spanish location, killing 63% of lines and significantly changing the frequency of ~5% of all genome-wide variants. A significant portion of this climate-driven natural selection over variants was predictable from signatures of local adaptation (R2=29-52%), as genetic variants found in geographic areas with climates more similar to the experimental sites were positively selected. Field-validated predictions across the species range indicated that Mediterranean and Western Siberian populations — at the edges of the species’ environmental limits — currently experience the strongest climate-driven selection. With more frequent droughts and rising temperatures in Europe4, we forecast an increase in directional natural selection moving northwards from the southern end, and putting many native A. thaliana populations at evolutionary risk.
