Phylogenetic placement and population genetic analysis of the endangered winged mapleleaf, Quadrula fragosa

The endangered winged mapleleaf, Quadrula fragosa once occurred in the Mississippi, Tennessee, Ohio, and Cumberland River basins in the United States. While the range of this species was thought to have been reduced to a single population in the St. Croix River (Minnesota/Wisconsin), individuals morphologically similar to Q. fragosa recently have been recorded in three southern states: Missouri, Arkansas, and Oklahoma. The aim of this study was two-fold. First to determine if Q. fragosa is a distinct species from Q. quadrula. Second, to determine whether these new records represent from the southern states represent true Q. fragosa. To address these aims, we employed a phylogenetic analysis of DNA sequences from the mitochondrial ND1 genes. Sequences for the nuclear Histone3 gene region were explored, but due to the high degree of conservation, phylogenetic analysis was not pursued further. Our results indicate that Q. fragosa is a separate species from Q. quadrula and that the southern populations are genetically Q. fragosa. The results of this study have identified a number of new disjunct populations of Q. fragosa. Considering the endangered status of this species, future conservation work should address genetic variation within and among the populations as well as the amount of gene flow between populations. Only then will the populations be rehabilitated, expanded, and removed from the endangered species list.