Genetic Diversity and Nutritional Quality Comparison in Schizothorax waltoni, Schizothorax o’connori, and Their Different Maternal Natural Hybrids

Natural hybridization plays an important role in species evolution, and its heterosis also provides inspiration for breeding. The present study is to compare the genetic diversity and muscle nutritional quality of Schizothorax waltoni, Schizothorax o’connori, and their natural hybrids that are naturally distributed in the Yarlung Zangbo River. Based on the cluster analysis, the genetic relationship between 13 hybrids (namely S. w. ♀ hybrid) and S. waltoni was found to be closely related, whereas 24 hybrids (namely S. o. ♀ hybrid) were closely related to S. o’connori. The haplotype polymorphisms across the four populations varied between 0.847 and 0.936, while the nucleotide polymorphisms were 0.00305–0.00418. The genetic diversity of the two hybrids was higher than that of S. waltoni and S. o’connori. The crude fat content of the two natural hybrids is significantly higher than that of S. waltoni and S. o’connori. The total amino acid (TAA), essential amino acid (EAA), and delicious amino acid (DAA) contents and the EAA index (EAAI) in the two hybrids were greater than those in S. waltoni and S. o’connori. Compare to S. waltoni (22) and S. o’connori (18), the two natural hybrids (both 24) showed the richer types of fatty acids. The highest contents of polyunsaturated fatty acids (PUFAs), ω-3 PUFAs, and ω-6 PUFAs were observed in S. waltoni, and ω-6 PUFA within the two hybrids possessed intermediate characteristics. In conclusion, the hybrids of S. waltoni and S. o’connori showed advantages of growth rate, genetic diversity, and nutrition quality, therefore appearing to have a potential of breeding for further development and utilization.