Table 3. Analysis of molecular variation (AMOVA) calculated from COI mtDNA sequences for N. douglasiae from seven collection locations in the middle and lower reaches of Yangtze River.

Source of variation	df	Sum of squares	Variance components	Percentage of variation
Among populations	6	158.375	1.979	11.99
Within populations	57	489.250	8.583	88.01
Total	63	647.625	10.562

All F-statistics were statistically significant (p<0.001).