Complex sentence: It is considered a superspecies with the russet sparrow ("Passer rutilans") and sometimes is even treated as the same species; similarities in plumage and morphology between the two seem to suggest convergent evolution rather than a single lineage.
Split into simpler sentences: It is considered a superspecies with the russet sparrow ("Passer rutilans") and sometimes is even treated as the same species. However, the similarities in plumage and morphology between the two seem to represent convergent evolution rather than a single lineage.