Date of this Version
Systematic Zoology (1972) 21: 106-116.
The genus Blarina (Mammalia: Soricidae) is represented in Nebraska by two well-differentiated, geographically exclusive phena that generally have been regarded as subspecies. Field studies conducted along their zone of contact resulted in the collection of representatives of both phena at each of five localities. Cluster analysis of distance matrix readily separated reference samples of the phena as well as test samples from near the zone of contact. A three-dimensional projection of the specimens onto their first three principal components, together with a discriminant function analysis, served further to elucidate the degree of differentiation among the phena and to confirm that their characteristic differences are maintained even where they occur sympatrically. The latter technique also indicated that one specimen not singled out by other analyses might be a natural hybrid, but none of the analyses provided even the slightest evidence for panmictic intergradation, The possibility that the phena represent the ends of a circularly intergrading species is considered, as is the possibility that the phena are distinct, biological species. Two means of speciation, one "classical" and the other involving formation of "stasipatric species," are discussed.