Leptodea

Abstract: The larvae of freshwater mussels in the order Unionoida are obligate parasites on fishes Because adult mussels are infaunal and largely sessile, it is generally assumed that the majority of gene flow among mussel populations relies on the dispersal of larvae by their hosts The objective of this study was to compare the genetic diversity and the degree of congruence between the population structures of two related freshwater mussels Leptodea leptodon and Leptodea fragilis and their fish host, Aplodinotus grunniens Host specificity in parasites has been shown to result in greater congruence between the population structures of the two interacting species, and assessing the congruence of genetic structure of the endangered L leptodon with its sister species L fragilis and their sole host is an important step in understanding the impact of host dispersal on population structure Analysis of microsatellite data indicated that despite its imperiled status, L leptodon displayed greater genetic diversity than the more common L fragilis However, the population structures of all three species were incongruent even in the presence of substantial gene flow Other factors such as habitat specificity may play a role in generating the differences in population structure observed This study indicates that barriers to gene flow or lack of available host fish are not the cause of decline of the federally endangered L leptodon, and suggests that alternative explanations should be considered

Abstract: Both overall abundance and species richness of freshwater mussels have declined over the past century. Mussels are natural ‘biofilters’ that provide important ecosystem services in the rivers. Thus, the decline of this fauna may have long-term, negative consequences for the functioning of river ecosystems. The major cause of mussel decline is from the alteration of the natural flow regime of rivers, primarily by impoundments and channelization. Hydrologic alterations impact mussels both directly through physical stress, such as temperature changes, siltation and scour, and indirectly through changes in habitat, food and fish-host availability. There are approximately 52 mussel species that presently occur in Oklahoma waters, with the highest biodiversity and healthiest populations in the southeast. For example, 41/55 species (80%) occur in the Kiamichi and Little River watersheds. Within these watersheds, the number of sites at which species occur and species abundances are declining, and the biological integrity of numerous subpopulations have been greatly decreased by the loss of individuals. Three federally endangered mussel species occur in these rivers, the Ouachita rock pocketbook (Arkansia wheeleri), the winged mapleleaf (Quadrula fragosa), and the scaleshell (Leptodea leptodon), while a fourth species, Quadrula cylindrica, the rabbitsfoot mussel, is being considered for listing.

Abstract: The Leptodea leptodon (Bivalvia: Unionidae) is native to the United States, it is threatened by human activities and habitat destruction. In the present study, it’s complete mitochondrial genome was reconstructed from whole-genome Illumina sequencing data with an average coverage of 1213X. The total length of mitogenome is 16,133 bp, which consists of 37 typical animal mitochondrial genes, including 22 transfer RNAs (tRNAs), 13 protein-coding genes (PCGs) and two ribosomal RNAs. The putative control region (329 bp) is located between ND5 and tRNA-Gln, with an A + T content of 67.4 %. The base composition of the genome is A (38.7 %), C (26.7 %), G (10.8 %) and C (26.7 %) with an overall GC content of 37.5 %. Phylogenetic analysis suggests that L. leptodon is closely related to its confamilial counterparts than to the other taxa.