Evaluation of sexual dimorphism in Ponticola cyrius in Tajan River using geometric-morphometric and traditional morphometric methods

The sexual dimorphism is one of the most subjects for biologists that create using natural selection on individual based on mating system, the ecological differences between individual and the pressure of natural selection on reproductive associated traits. The aim of this study is evaluate of sexual dimorphism in Ponticola cyrius in Tajan River using geometric-morphometric and traditional morphometric methods. So, 40 ponticola cyrius (male= 20 and female=20) were caught from Tajan River. Then, 31 absolute morphometric characterizes measured and also 27 relative morphometric characterizes calculated. For comparison of geometric-morphometric was provided the images from left side- view, dorsal and abdominal views. In order to extract data from the body shape the 20, 19 and 12 landmarks determined in the side, abdominal and dorsal view, respectively, and then digitalized by tpsDig2 software on 2D pictures. Then, the obtained data was analyzed by procrustes methods. The obtained results from using geometric-morphometric and traditional morphometric analysis were evaluated using Principal component analysis, Discriminant function analysis and T tests. The results indicated a significant difference between female and male in all of the mentioned views. According to our results, the male of ponticola cyius has more length, body width, head height, length of dorsal fin base and anus than female ones. In addition, the color of male fish was darker than female and sexual papilla in male is more keen and length than female. The results of traditional and geometric morphometric studies largely confirmed each other.