Identification and characterization of the contact zone between two species of short-tailed shrews (Blarina) in southern Iowa and northern Missouri. Cody W. Thompson1, Elmer J. Finck1, Jerry R. Choate1, and Hugh H. Genoways2. 1Fort Hays State University, Hays, KS and 2University of Nebraska-Lincoln, Lincoln, NE.

Species of the mammalian genus Blarina are characterized by divergent karyotypes and can be distinguished using DNA, but they remain essentially identical morphologically and highly similar morphometrically. Wherever the ranges of two of the species approach each other, one species is larger than the other although the ranges of measurements overlap. Possibly as a result of this close similarity, adjacent species of Blarina tend not to occur sympatrically, but rather exhibit a parapatric distribution. The best studied contact zones separates B. hylophaga and B. brevicauda in Nebraska. At that location, the species exhibit a parapatric relationship. However, morphometric data suggest that the same two species occur sympatrically in a large area of southern Iowa and northern Missouri. To ascertain the true nature of the latter contact zone, we began collecting Blarina specimens in southern Iowa and northern Missouri in May of 2005. Karyotypes of trapped specimens are being used to identify the specimens and ascertain the nature of the contact zone. So far, 74 specimens have been collected and 42 specimens have been positively karyotyped. Additionally, genetic analyses will be used to investigate the extent of hybridization between the species in the contact zone. Average width and range of the contact zone will be calculated to determine its size and extent, and this information will be used to help characterize the geographic relationship between these species as parapatric or sympatric.