Predicting rapid adaptation in time from adaptation in space: a 30-year field experiment in marine snails

Predicting the outcomes of adaptation is a major goal of evolutionary biology. When temporal changes in the environment mirror spatial gradients, it opens up the potential for predicting the course of adaptive evolution over time based on patterns of spatial genetic and phenotypic variation. We assessed this approach in a 30-year transplant experiment in the marine snail Littorina saxatilis . In 1992, snails were transplanted from a predation-dominated environment to one dominated by wave action. Based on spatial patterns, we predicted transitions in shell size and morphology, allele frequencies at positions throughout the genome, and chromosomal rearrangement frequencies. Observed changes closely agreed with predictions. Hence, transformation can be both dramatic and rapid, and predicted from knowledge of the phenotypic and genetic variation among populations. ### Competing Interest Statement The authors have declared no competing interest.