Shrew Evolutionary BiologyI have recently begun to work again on shrews, small mammals that formed the basis of my PhD dissertation in the 1990s. In particular, I examined two species groups of red-toothed shrews (Sorex) that occur in western North America, including some species spilling over into Far East Asia. The cinereus and vagrans groups consist of multiple species of shrews with extensive cryptic genetic diversity, which in some instances might represent new species and possess some very interesting phylogeographic patterns. More recently, in collaboration with Andrew Hope (Kansas State University), we examined North America’s smallest mammal, the pygmy shrew (Sorex hoyi), which weighs in at 2 to 4 grams and is widely distributed across the North American boreal forest biome. An isolated population, S. h. montanus, also occurs in Colorado and Wyoming above 2,800 meters.
Shrews can be very difficult to identify; commonly, characteristics of the teeth, particularly the size and number of unicuspids (one-cusp teeth), are diagnostic. However, this approach can be ambiguous and doesn’t account for underlying cryptic diversity. To this end, we’ve begun to “DNA Barcode” shrews in the Denver Museum of Nature & Science mammal collection. This work is being conducted in the Genetics Lab and will involve our community scientists. This will allow us to definitively identify the specimens in our collection and generate preliminary genetic data.