Rapid parallel adaptation to anthropogenic heavy metal pollution

The impact of human mediated environmental change on the evolutionary trajectories of wild organisms is poorly understood. In particular, species’ capacity to adapt rapidly (in hundreds of generations or less), reproducibly and predictably to extreme environmental change is unclear. Silene uniflora is predominantly a coastal species, but it has also colonised isolated, disused mines with phytotoxic, zinc-contaminated soils.

Here, we found that rapid parallel adaptation to anthropogenic pollution has taken place without geneflow spreading adaptive alleles between populations of the mine ecotype. Across replicate ecotype pairs, we identified shared targets of selection with functions linked to physiological differences between the ecotypes, although the genetic response is only partially shared between mine populations.

Our results are consistent with a complex, polygenic genetic architecture underpinning rapid adaptation. This shows that even under a scenario of strong selection and rapid adaptation, evolutionary responses to human activities may be idiosyncratic at the genetic level and, therefore, difficult to predict from genomic data.