Body shape variation in riffle minnows (Alburnoides eichwaldii De Filippii, 1863) populations of Caspian Sea basin Print

The objective of this study was to determine the body shape variation among riffle minnows (A. eichwaldii) populations in the Caspian Sea basin using landmark-based geometric morphometrics. A total of 260 specimens were sampled from four streams of Gorganroud River, Valamroud River and two streams of Sefidroud River. The left side of each specimen was photographed using digital camera and eighteen landmark points were digitized on two-dimensional images using TpsDig2. Landmark data after generalised procrustes analysis were analyzed using PCA, CVA and cluster analysis and the patterns of body shape differences among the studied populations were illustrated in deformation grids in relation to consensus configuration of all specimens. CVA analysis displayed significant differences among all populations except two populations sampled in Sefidroud River (P<0.05). Results also showed habitat-associated morphological divergence, phenotypic plasticity and evolutionary process of body shape change among various populations and also, a relationship between the geographical distance and the degree of morphological divergence among populations in response to environmental factors in their habitat. The results also could be taken as evidence to consider the populations as separate stocks.