Analysis of genetic diversity in wild populations of Trachidermus fasciatus   by RAPD and the transformation of two SCAR markers

Firstly, RAPD was conducted to analyze genetic diversity of Trachidermus fasciatus

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in the Fuchun River population (FR), Yellow River population (YR), Luan River population (LR), and Yalu River population (YL), with 32 polymorphic 10-bp random primers selected from 294 ones. Thirty wild individuals were detected in each population. The results indicated that the genetic diversity of T . fasciatus was relatively rich. The major results were as the following: 1) Altogether, 591 bands were detected and 515 of them were polymorphic, accounted for 87.14%. The range of proportion of polymorphic loci (P) was: FR(89.17%)>YR(87.99%)>YL(86.63%)>LR(83.25%). 2) The Shannon’s information index(I_T) and Nei’s genetic diversity(H_T) among populations were 0.3393−0.3566 and 0.2157−0.2279, respectively. Compare to other three populations, LR population had relative lower values. If took the populations as a whole, the total Nei’s genetic diversity(H_T) and Shannon’s information index(I_T) was 0.2336±0.1643 and 0.3710±0.2153, respectively. 3) The value of gene flow (N_m) (5.76103−19.84497) were high, indicating certain gene exchange existed among the four populations. But the AMOVA results exhibited significantly differentiation (P<0.05 or P<0.01) among the populations. 4) In the UPGMA tree constructed according to genetic distance, YL and YR populations clustered firstly, then with FR population, and finally they joined to LR population. Obviously, the YL, YR and FR populations had relatively close relationship according to their geographic distance, whereas LR population showed clear divergence to the other three populations. Secondly, out of the five special RAPD bands (S₁₂₂₅ ^{525 bp}, S₁₂₂₅ ^{605 bp}, S₁₂₂₅ ^{841 bp}, S₁₃₄₅ ^{695 bp} and S₁₃₄₅ ^{825 bp}), SCAR maker SCAR01^{560 bp} and SCAR02^{443 bp} were successfully transformed from S₁₂₅₅ ^{605 bp} and S₁₂₅₅ ^{841 bp}, respectively. After large samples examination of the two markers, we found the highest frequency (96.67% and 93.33%) in the YL population, higher frequency (83.33% and 90%) in the FR population, high frequency (56.67% and 66.67%) in the YR population, and the lowest frequency (13.33% and 20 %) in the LR population. Therefore, SCAR01^{560 bp} and SCAR02^{443 bp} can be used as special molecular markers for the population identification between LR and other three populations.