Phenotypic variation across chromosomal hybrid zones of the common shrew (Sorex araneus) indicates reduced gene flow. oleh P David Polly, Andrei V Polyakov, Vadim B Ilyashenko, Sergei S Onischenko, Thomas A White, Nikolay A Shchipanov, Nina S Bulatova, Svetlana V Pavlova, Pavel M Borodin, Jeremy B Searle