ASSESSING GENETIC DIVERSITY WITHIN AND AMONG POPULATIONS OF TWO MUSSELS OF THE GENUS QUADRULA.

Matthew J. Cox, Daniel J. Hornbach, Paul J. Overvoorde, Mark C. Hove, Macalester College, Department of Biology

With the rise of molecular techniques, we now have powerful new tools to inform conservation efforts. By examining the genetic diversity within and between populations, we can characterize the amount of genetic variability that exists between two or more populations. This in turn can influence the decision of biologists to treat groups of organisms as a single conservation unit or to treat them separately. We are currently working on a project to assess the genetic diversity within and among populations of two freshwater mussels: Quadrula quadrula (common mapleleaf) and Quadrula pustulosa (Pimpleback). We have collected tissue samples from populations on the St. Croix and Mississippi Rivers. Two molecular markers have been chosen for sequencing: the mitochondrial gene ND1 and the nuclear-encoded internal transcribed spacer region ITS-1. After sequencing we will assess the sequences to characterize the diversity present. These findings will put into context the genetic makeup of other mussel species in this genus, such as the endangered Quadrula fragosa and will build on earlier work we conducted using restriction fragment length polymorphisms of ITS-1 to differentiate among various Quadrula species.

Suggested reading

King, TL, Eackles, MS, Gjetvaj, B, Hoehw WR. 1999. Intraspecific phylogeography of Lasmigona subviridis (Bivalvia: Unionidae): conservation implications of range discontinuity. Molecular Ecology 8:S65-S78. Serb, JM, Buhay, HE, Lydeard, C. 2003. Molecular systematics of the North American freshwater bivalve genus Quadrula (Unionidae: Ambleminae) based on mitochondrial ND1 sequences. Molecular Phylogenetics and Evolution 28:1-11.