Freshwater crayfish are poor dispersers – predominately moving by crawling across the bottom of rivers and creeks – so it is hard to imagine that individuals, separated by over 2000kms of waterways, can be genetically similar and form part of a single interbreeding grouping. These findings were revealed in our Murray crayfish population genetics study, based on 20 locations across the present range of species, recently published in Marine and Freshwater Research (here).