Cooperative Fish and Wildlife Research Units Program: Arizona
Education, Research and Technical Assistance for Managing Our Natural Resources

Goal: Historically, freshwater mussels of the genus Anodonta inhabited at least portions of many or most of the major drainage systems in Arizona. Today, the known distribution of native Anodonta in Arizona is restricted to a few miles of perennial flowing waters in the upper Black River of the Colorado River system. In fact, some information indicates this to be the only known extant population of Anodonta remaining in the entire Colorado River system, although it is likely that Anodonta exist elsewhere in the Rio Yaqui system in Mexico. Freshwater mussels from Arizona are considered to be Anodonta californiensis, however, the relatedness of these mussels to other con-generic species in western North America has not been determined. The relationship of Arizona’s Anodonta to populations in western Mexico is unknown. The objective of this study is to quantify the genetic relatedness between populations of freshwater mussels of the genus Anodonta in Arizona and western Mexico to enable a clarification of their taxonomic relationships.