 In this way, when previously genetically or phenotypically uniform populations spread into novel environments, they will evolve to be uniquely adapted to the local environment, in the process potentially creating a gradient in a genotypic or phenotypic trait.Such clines in characters can not be maintained through selection alone if lots of gene flow occurred between populations, as this would tend to swamp out the effects of local adaptation.However, because species usually tend to have a limited dispersal range (e.g.