We introduce a minimal model of population range expansion in which the phenotypes of individ- uals present no selective advantage and differ only in their diffusion rate. We show that such neutral phenotypic variability can yield alone phenotype segregation at the front edge even in absence of genetic noise, and significantly impact the dynamical properties of the expansion wave. We present an exact asymptotic traveling wave solution and show analytically that phenotype segregation ac- celerates the front propagation. The results are compatible with field observations such as invasions of cane toads in Australia or bush crickets in Britain
