Co-varying patterns of genetic diversity and structure with life-history traits of freshwater mussel species (Bivalvia:Unionidae) in the Poyang Lake Drainage, China

Freshwater mussels are one of the most diverse groups of freshwater organisms as well as one of the most endangered groups of organisms on Earth. Freshwater mussels have a life history that greatly influences their geographical distribution, genetic structure, and demographic characteristics. Here, we describe and compare the spatial genetic structure and diversity of 5 freshwater mussel species with different brooding periods and uses of larval parasitism. These 5 species co-occur in tributaries in Poyang Lake in south central China, and we studied their populations in the Gan and Fuhe Rivers, which are both large tributaries of Poyang Lake. Cytochrome c oxidase subunit-I (COI) haplotype richness and diversity of species with a spring or summer glochidia brooding period (Lamprotula caveata, Nodularia douglasiae, and Solenaia oleivora) were greater than richness and diversity in species with a winter brooding period (Anemina arcaeformis, S. carinata). In addition, the COI haplotype richness and diversity of A. arcaeformis, which does not have a parasitic portion of its life cycle, was lower than 3 species that require a host fish to complete their life cycles (L. caveata, N. douglasiae, and S. oleivora) and was higher than S. carinata. We also used the COI sequences and microsatellite datasets to determine whether the populations of each of the 5 species in the Gan and Fuhe Rivers are admixed or genetically distinct. Genetic differentiation was evident among collection populations of L. caveata, N. douglasiae, and S. carinata and largely absent in A. arcaeformis and S. oleivora. We conclude that differences in genetic diversity and patterns of genetic structure in these sympatric species could result from the different life-history attributes of these species, particularly timing and length of the brooding period, non-parasitic vs parasitic life cycles, and different host fish requirements. Therefore, we suggest increased emphasis on life history and reproductive biology research and urge managers to consider that these traits differ among freshwater mussels when making management decisions for the conservation of genetic and species diversity.