Local adaptation of life-history traits within urban populations of Arabidopsis thaliana

Abstract

AbstractThe challenges to which plants are exposed in urban environments represent, in miniature, the challenges plants face as a result of global environmental change. Hence, urban habitats provide a unique opportunity to assess whether processes of local adaptation are taking place despite the short temporal and geographical scales that characterize the anthropoceneWe quantified the ecological diversity of spontaneously occurring urban habitat patches of A. thaliana. Using plant community indicators, we show that these patches differ in their levels of soil nutrient content and disturbance. Accordingly, plants in each patch displayed significantly different flowering time, size, and fitness.Using a deep sampling approach coupled with reduced genome-sequencing, we demonstrate that most individuals can be assigned to a limited set of clonal lineages; the genetic diversity of these lineages represents the diversity observed in western European populations of the species, indicating that established urban populations originate from a broad regional pool of lineages.We assessed the genetic and phenotypic diversity of these lineages in a set of common garden experiments. We report marked genetic differences in life-history traits, including time of primary and secondary dormancy as well as of flowering. These genetic differences in life-history traits are not randomly distributed but sorted out by ecological differences among sites of origin.Synthesis: Our study shows that the genetically diverse phenology of a regional A. thaliana gene pool is not randomly distributed but filtered by urban environmental heterogeneity. This report is the first to show a pattern of local genetic adaptation within urban environments. We conclude that environmental filtering helps maintain functional diversity within species.