Location of the Blarina contact zone in southwestern Iowa and northwestern Missouri: Implications for genetic analysis. Cody W. Thompson1, 2, Elmer J. Finck1, Jerry R. Choate2, and Hugh H. Genoways3. 1Department of Biological Sciences, Fort Hays State University, Hays, KS; 2Sternberg Museum of Natural History, Fort Hays State University, Hays, KS; and 3University of Nebraska State Museum, University of Nebraska, Lincoln, NE.

Short-tailed shrew (Blarina) species are characterized by divergent karyotypes and can be distinguished by using DNA, but they remain essentially identical morphologically and highly similar morphometrically. Possibly as a result of this similarity, adjacent Blarina species tend not to occur sympatrically, but rather parapatrically. The best studied contact zone separates the Elliot’s short-tailed shrew (B. hylophaga) and the northern short-tailed shrew (B. brevicauda) in Nebraska, where the species exhibit a parapatric relationship. However, morphometric data suggest that the two species occur sympatrically in southern Iowa and northern Missouri. To ascertain the nature of the latter contact zone, we collected Blarina specimens in southwestern Iowa and northwestern Missouri from May 2005 to August 2006. External measurements (for tentative identification) and karyotypes have been used to identify specimens and ascertain the nature of the contact zone. We have collected a total of 179 Blarina specimens in the study area. One hundred and forty-three specimens have been identified tentatively by total length. In addition, 104 specimens have been karyotyped, 100 of which have been identified positively. Amplified fragment length polymorphism analyses will be used to investigate the extent of hybridization between the two species. The degree to which hybridization occurs between the two species will be necessary in determining the integrity of the gene pools of each species. Average width and range of the contact zone will be calculated to determine its size and extent, and this information will be used to characterize the geographic relationship between these species as parapatric or sympatric.