Patterns of Body Shape Variation in Capoeta gracilis (Pisces: Cyprinidae) in Relation to Environmental Variables in Sefidrud River Basin, Iran

Abstract

This study investigates the morphological variation of Capoeta gracilis (Cyprinidae) in relation to the environmental conditions across its distribution range in the Sefidrud River basin. The correlations between environmental variables and body shape of 487 specimens of C. gracilis was studied using a combination of geometric morphometric technique and multivariate statistical analysis i.e. Two-Block Partial Least-Squares (2B-PLS). The studied environmental variables were including depth (cm), width (m), slope (m/km), current velocity (cm/s), number of large stone (>25 cm), average stone diameter (cm), substrate index (%), Potamal Cover Index, Periphyton Cover Index. The body shape of fishes living in habitats with fast flow water and lower depth, substrate index, PeCI and PoCI as seen in specimens of downstream of Taleghan and Totkabon Rivers, are fusiform including smaller head, longer caudal peduncle and relatively deeper body. The results also showed that increasing depth and width of river along with increasing PeCI, PoCI and larger bed stones induce larger head and shorter and deeper caudal peduncle forming relatively deeper body shape. The most of observed differences were in head and tail regions, but in lower degree suggesting C. gracilis as a generalist species. Based on the results, ecomorphological analyses is a valid tool to predict habitat preferences in the genus Capoeta in riverine ecosystems

Keywords

• Ecomorphology, Geometric morphometric, 2B-PLS, Phenotypes, Environmental variation