In this contribution we present our reasearch of vernal pools along large river coridors in the Czech Republic in 2005-2009. Using model organism fairyshrimp Eubranchipus grubii we show that after the retreat of last land glacier, landscape in the watershed of Oder underwent different development than watersheds of Elbe and Morava, and the populations inhabiting Odra watershed have different origin (probably from the steppes in the east).