Parallel shape divergence between ecotypes of the limpet Nacella concinna along the Antarctic Peninsula: a new model species for parallel evolution?

•The extent of parallel divergence in ecotypes of Nacella concinna was analysed.•Littoral and sublittoral ecotypes belong to one single evolutionary lineage.•There is a remarkable parallel morphological divergence pattern in their shells.•This species is a suitable model for studying the role of parallel evolution.