Effect of dam on genetic structure of Capoeta capoeta gracilis in the Tajan River

Dams can potentially affect the size of populations and their connectivity, reduce genetic variation and increase genetic differences among isolated riverine fish populations. Therefore, in this research, the effect of Shahid Rajaee dam on the genetic variation of Capoeta capoeta gracilis in the Tajan River was investigated using sequences of cytochrome b gene. The Capoeta capoeta gracilis samples were collected from upstream and downstream of the dam. Sequence and analysis of this gene showed 11 haplotypes in the samples. Nucleotide diversity and haplotype diversity were 0.00062, 0.00939, 0.37778 and 0.70526 for upstream and downstream populations, respectively. Analysis of molecular variance (AMOVA) showed that 88.45% of genetic variation contained within population and 6.21% of genetic variation among groups. The analysis of the FST showed that there is a significant genetic difference between the studied populations. In total, it can be concluded that there was a significant genetic differentiation between the upstream and downstream populations of the Capoeta capoeta gracilis in the Tajan River (P = 0.05). However, this conclusion should be cautious, because only one gene was used in this research. For better results, it is recommended to use other genes as well as other genetic indexes such as microsatellite and in addition, similar studies need to be performed in other rivers.