Investigation of Misgurnus anguillicaudatus and Paramisgurnus dabryanus in the Yangtze River basin

The distribution patterns of Misgurnus anguillicaudatus and Paramisgurnus dabryanus were investigated in the Yangtze River basin.Specimens of four different ploidy levels were found as diploid (2n=50),triploid (3n=75),tetraploid (4n=100) and pentaploid (5n=125).Diploids were dominant,exhibiting broadly ecological amplitude.Polypoid M.anguillicaudatus populations were concentrated in the middle reaches of the Yangtze River and its subsidiary lakes.The weight of females in both M.anguillicaudatus and P.dabryanus was significantly greater than that in males (P <0.005).However,there was no statistically significant difference between the growth traits of two species.The body length and weight of diploid M.anguillicaudatus were lower than that of triploid (P <0.005) and tetraploid (P <0.001).There was no significant difference in growth traits between triploid and tetraploid M.anguillicaudatus.Female proportion in M.anguillicaudatus populations gradually decreased from upstream to downstream,whereas in P.Dabryanus it fluctuated and no obvious trend was observed.The GLM linear regression analysis found that the body weight of M.anguillicaudatus was negatively correlated with longitude (r=-0.510),while no significant correlation was observed for P.Dabryanus (r=-0.177).This study proves the presence of P.Dabryanus and M.anguillicaudatus specimens of four different ploidy levels in natural populations in the Yangtze River basin,suggesting the need for further scientific attention and consideration of possible conservation measures.