Morphological and molecular analyses of Anodontinae species (Bivalvia, Unionidae) of Lake Baikal and Transbaikalia.

The diversity and taxonomy of anodontine species in Lake Baikal and Transbaikalia region has been contentious since it is based on a typological species concept, the so called "Comparatory Method". Using this method, six Comparatory anodontine species have been described for the study area as belonging to the genus Colletopterum. This genus was separated from Anodonta based on shell characteristics and further split into two subgenera, i.e. Colletopterum sensu stricto and Colletopterum (Piscinaliana). However, many authors do not recognize this separation maintaining all Colletopterum forms within Anodonta. The current study clarifies the taxonomy and systematics of Anodontinae in this region, using a combination of molecular, morphological and anatomical data. All previously recognized Comparatory forms are here recognized as a single species, i.e. Anodonta anatina.

The complete F-type mitochondrial genome of Chinese freshwater mussel Anodonta euscaphys.

Anodonta euscaphys is the endemic species of freshwater mussel in China. The complete F-type mitochondrial genome of the A. euscaphys is amplified and analyzed in this study. It is 15,741 bp in length. The base composition of the genome with A + T bias is 64.78%. There are 24 noncoding regions found throughout the mitogenome of A. euscaphys, ranging in size from 3 to 302 bp, the largest of which was between ND2 and tRNA(Glu). The phylogenetic tree based on 22 mitogenome, including 16 F-type freshwater mussels, 2 M-type freshwater mussels and 4 marine mussels were analyzed in our study, the results showed that the F-type and the M-type of the freshwater mussels were clustered respectively, the A. euscaphys was clustered with Anodonta family species firstly, and it was the closest to the Anodonta arcaeformis in our analysis.

Comparison of population genetic patterns in two widespread freshwater mussels with contrasting life histories in western North America.

We investigate population genetic structuring in Margaritifera falcata, a freshwater mussel native to western North America, across the majority of its geographical range. We find shallow rangewide genetic structure, strong population-level structuring and very low population diversity in this species, using both mitochondrial sequence and nuclear microsatellite data. We contrast these patterns with previous findings in another freshwater mussel species group (Anodonta californiensis/A. nuttalliana) occupying the same continental region and many of the same watersheds. We conclude that differences are likely caused by contrasting life history attributes between genera, particularly host fish requirements and hermaphroditism. Further, we demonstrate the occurrence of a 'hotspot' for genetic diversity in both groups of mussels, occurring in the vicinity of the lower Columbia River drainage. We suggest that stream hierarchy may be responsible for this pattern and may produce similar patterns in other widespread freshwater species.