Low genetic and phenotypic divergence in a contact zone between freshwater and marine sticklebacks: gene flow constrains adaptation
Abstract Background Distinct hybrid zones and phenotypic and genomic divergence is often observed between marine and freshwater threespine sticklebacks (Gasterosteus aculeatus).Nevertheless, cases also exist where marine-freshwater divergence is diffuse despite seemingly similar environmental settings.In order to assess what characterizes these hig