Scientists have shown that the Italian sparrow is a newly evolved species of the sparrow family. DNA analysis shows that it originated as a hybrid of the house sparrow and the Spanish sparrow. However, it is now breeding true and is not interbreeding with the Spanish sparrow in areas where they occupy the same range. That is one of the more practical definitions of species.
…this study, led by evolutionary biologist Glenn-Peter Saetre from the University of Oslo, is a genetic snapshot that appears to settle the debate.
Reference: Hybrid speciation in sparrows I: phenotypic intermediacy, genetic admixture and barriers to gene flow. Jo S. Hermansen, Stein A. Sæther, Tore O. Elgvin, Thomas Borge, Elin Hjelle, Glenn-Peter Sætre. Article first published online: 19 JUL 2011. DOI: 10.1111/j.1365-294X.2011.05183.x