Trends in morphological relationships among Gangetic Cyprinids

Abstract

Cyprinidae is the predominant and most diverse taxonomic group of freshwater fishes, exhibiting enormous diversity in shape, size and biology. The morphological diversity of Indian Cyprinids especially the Gangetic Cyprinids is largely unquantified. Geometric morphometrics (GM) approach is an efficient tool to quantify overall body shape variations and has wide application in taxonomic, evolutionary and ecological studies. In this study, digital photographs of 47 Cyprinid fish species from Ganga River were used to measure geometric body shape so as to evaluate interspecific morphometric relationships. Combined results of principal component analysis (PCA), canonical variate analysis (CVA) and Cluster analysis (CA) revealed interspecific differences in Cyprinid fishes. Phenogram showed that all the species of different genus like Barilius, Garra, Labeo, Pethia, Schizothorax and Tor are clustered together in their respective group. This indicates that species of respective genus share common phenotypic traits and there is evolutionary relatedness among them. The present study showcases the efficient use of digital images and strongly supports the application of cost–effective GM method in discriminating distinct groups and representing the morphological relationships between species of Cyprinid fishes. Overall, we suggest that the body shape disparity and proximity among groups can therefore be used as an effective approach in rapid diagnosis of a species and understanding evolutionary relationships between species.