Complex sentence: Initial single gene genetic analysis of the genus using mitochondrial DNA showed the three raven species to belong to one lineage and the two crows to another however, the crow lineage and raven lineage may not be closely related as the only close similarity is the eye colour.
Split into simpler sentences: Initial single gene genetic analysis of the genus using mitochondrial DNA showed the three raven species to belong to one lineage and the two crows to another. The crow lineage and raven lineage may not be closely related as the only close similarity is the eye colour.