Absence of genetic structure reflects post-glacial history and present-day host use in Mapleleaf (Quadrula quadrula) mussel from Manitoba, Canada

Abstract

Our study documents and analyzes the absence of genetic diversity and structure of the Mapleleaf (Quadrula quadrula (Rafinesque, 1820)) (Bivalvia: Unionidae) mussel in the Lake Winnipeg, Assiniboine River, and Red River drainages (Manitoba, Canada). Previous studies have revealed patterns of genetic diversity and structure in the Mississippi and Ohio river drainages, as well as in the Laurentian Great Lakes drainage. Genotypes from six variable microsatellite loci showed that the Q. quadrula population in Manitoba was significantly differentiated from the population in the Great Lakes drainage (Ontario, Canada), supporting the existence of two Designatable Units in Canada. Conversely, there was no evidence of genetic structure within the sampled range of Q. quadrula in Manitoba. The lack of genetic structure in Q. quadrula across its distribution in Manitoba reflected its post-glacial history and use of a vagile host and necessitates that efforts should be made to ensure connectivity and maintain gene flow across the region. Given that the evidence suggests that Manitoba Q. quadrula belong to a single genetic population, movement of hatchery-propagated juvenile Q. quadrula, adult Q. quadrula, or glochidia-carrying host catfish sourced from any location in Manitoba could be used to augment declining populations or at-risk locations in Manitoba.