Rapid phenotypic evolution in natural populations has been documented in many species and can occur on a timescale of decades or even years. In few studies, genotype-by-environment interactions for fitness have even been demonstrated to occur at a very small spatial scale within a plant population. However, to our knowledge, no study specifically tested whether the microevolution rate of a plant population was dependent on a small spatial scale of ecological variation. The identity of the natural genetic variants underlying GxE interactions at a very small spatial scale is also on open question.

Based on 195 seed families collected over eight generations in a highly polymorphic local French population of the annual selfing species Arabidopsis thaliana, we combined a resurrection study with an in situ reciprocal transplant study. Because soil variation and variation in plant – plant interactions occurs at a small scale in this population, the 195 local families have been phenotyped in six environments corresponding to a combination of three soil types and two competition treatments with the annual bluegrass Poa annua. In addition, the whole genome of these 195 families has been sequenced using the NGS Illumina technology.

Rapid phenotypic evolution was observed for 29 traits related to survival, phenology, resource acquisition, architecture and seed dispersal. The rates of evolutionary change were however highly dependent on the phenotyping environment. Based on a Genome-Wide Association mapping approach, I will also present some results on the identification of genetic variants associated with natural variation of fitness related traits.