The present study deals with the assessment of genetic diversity using microsatellite marker in the fish Labeo gonius from Nanak Sagar and Dhaura reservoirs of Uttarakhand having different morpho-edhaphic features and self- recruiting populations of this fish. These reservoirs are distantly located and distinctly separated without any connection having negligible possibility of gene exchange with each other. Total 12 cross amplified microsatellite primers after using software Primer-BLAST and Primer-3 were screened in all 100 DNA samples of fish collected from both the reservoirs. 12 cross amplified microsatellite primers were screened and successfully amplified. After PCR amplification of microsatellite loci and performing native PAGE using amplified DNA samples as above, POP GENE Version 1.32 was used to calculate Nei’s observed heterozygosity, expected heterozygosity, Nei’s genetic diversity, Fixation index (Fis) and Shannon’s information index (SI) and genetic variability indices viz. Gene flow(Nm), the coefficients of genetic differentiation (Fst & Gst) and Nei’s genetic distance. Overall Gst value (0.1601) recorded for L. gonius suggested the possibility of less gene exchange among the two stocks and indicated that 16.01% variation was attributable to interstock divergence, while 83.99% to individual differences within the stocks. Nei’s genetic diversity, calculated from the banding pattern of every primer, ranged from 0.4368 to 0.6922 with mean value of 0.5732 for specimens from Dhaura reservoir whereas it ranged from 0.5136 to 0.8243 with mean value of 0.6770 in specimens from Nanak Sagar reservoir. The observed and expected heterozygosities ranged from 0.4769 to 0.4981(mean value- 0.4901) and 0.5014 to 0.5267(mean value- 0.5169) respectively in L. gonius from Dhaura reservoir. The observed and expected heterozygosities ranged from 0.4641 to 0.5314 (mean value- 0.5046) and 0.4768 to 0.5682 (mean value- 0.5225) respectively in Nanak Sagar reservoir stock. Slightly better level of observed heterozygosity observed in fish from Nanak Sagar reservoir than Dhaura reservoir might be due to more differentiated stock of Nanak Sagar. Lesser value of observed heterozygosity compared to expected heterozygosity in fish from Dhaura reservoir might be possibly due to increased inbreeding in successive generations owing to small population size restricting desired germplasm exchange of appropriate genetic diversity. These observations indicated that the L. gonius stock of Nanak Sagar reservoir is genetically more diverse and differentiated as compared to its stock from Dhaura reservoir.

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