Range expansions and biological invasions are prime examples of transient processes that are likely impacted by rapid evolutionary changes. As a spa- tial process, range expansions are driven by dispersal and movement beha- viour. Although it is widely accepted that dispersal and movement may be context-dependent, for instance density-dependent, and best represented by reaction norms, the evolution of density-dependent movement during range expansions has received little experimental attention. We therefore tested current theory predicting the evolution of increased movement at low den- sities at range margins using highly replicated and controlled range expan- sion experiments across multiple genotypes of the protist model system Tetrahymena thermophila. Although rare, we found evolutionary changes dur- ing range expansions even in the absence of initial standing genetic varia- tion. Range expansions led to the evolution of negatively density-dependent movement at range margins. In addition, we report the evolution of increased intrastrain competitive ability and concurrently decreased popula- tion growth rates in range cores. Our findings highlight the importance of understanding movement and dispersal as evolving reaction norms and plas- tic life-history traits of central relevance for range expansions, biological invasions and the dynamics of spatially structured systems in general.