Background. The paddlefish, Polyodon spathula (Walbaum, 1792), is an important species for commercial and recreational fisheries throughout the central United States. Populations have declined in many areas due to river modification, loss of spawning habitat, pollution, and over-exploitation. Assessing genetic diversity of a species is an important consideration for developing conservation plans. The goal of this research was to perform a broad range survey of paddlefish diversity by evaluating populations from geographically distant major rivers of the United States of America. Materials and methods. Paddlefish samples were collected from four sites including the Alabama River, Red River, Yellowstone/Missouri River, and Ohio River. Eight microsatellite loci (PspD102, PspD111, PspB105, PspD9, PspD8, PspC6, PspH26, and PspC10) that displayed disomic inheritance patterns were used for the amplification of alleles. Results. Average allelic richness of four sites ranged from 7.50 ± 1.36 to 5.46 ± 0.91. Average expected heterozygosity ranged from 0.717 ± 0.085 to 0.591 ± 0.093, the average observed heterozygosity assumed the values from 0.711 ± 0.115 to 0.585 ± 0.087. A moderate level of between population diversity was observed with an overall Fst value of 0.0702. Hardy–Weinberg equilibrium revealed that seven loci in the four populations were in equilibrium. The four populations were clustered to two categories by cluster analysis (UPGMA) based on Fst and δμ2 distance. Conclusion. Four studied paddlefish populations exhibited relatively low levels of genetic diversity and close relative relations, but still had some differentiation among the populations. The genetic distance and Fst revealed that the Ohio River, Red River and Yellowstone/Missouri River populations belong to the same branch, while the Alabama River population from another branch.

Polyodon, molecular marker, geographic structure, genetic variety