Tracing the effects of Sefidrud dams on Capoeta gracilis (Cyprinidae) populations using Truss distances in southern Caspian Sea basin

It is postulated that building of Manjil and Tarik dams on Sefidrud River has led to morphological divergence of Siah Mahi, Capoeta gracilis of up-and downstream populations due to isolation. To test this, a total of 97 individuals of C. gracilis were collected from three sampling sites, including upstream of Manjil dam, upstream of Tarik dam and downstream of Tarik dam, in November 2013. A 13-landmark morphometric truss network system was used to investigate the hypothesis. Principal component analysis (PCA), canonical variates analysis (CVA), linear discriminant function analysis (DFA) and clustering analysis (CA) were used to examine morphological differences among the populations. Univariate analysis of variance showed significant differences among the means of the three groups for 48 standardized morphometric measurements out of 78 characters studied. In, DFA the overall assignment of individuals into their original groups was 77.8%. The PCA scatter plot of individual component scores between the first and second factors showed 97 fish specimens grouped into three areas but with a relativity low degree of overlap among the three populations. Cluster analysis indicating different populations of C. gracilis in up- and downstream Manjil and Tarik dams in Sefidrud River. The present study indicated the presence of morphologically different populations of C. gracilis in up and downstream of Manjil and Tarik dams in Sefidrud River, probably, is due to their limited downstream dispersal and elimination of upstream migration altogether, due to the construction of the dams.