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Dryad

Diversification of body shape in catfishes of the Ganga River

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May 04, 2022 version files 56.07 KB

Abstract

Catfishes of the order Siluriformes are an exceptionally diverse group occupying significant fraction of the world's freshwater ichthyofauna. Catfish species renders a model system for phylogenetic and evolutionary studies. However, there is dearth of knowledge on the phylogenetic history with reference to morphological diversity of catfishes in the Ganga River. Geometric morphometrics is an efficient approach to quantify shape variations and has lately found application in range of taxonomic, phylogenetic and evolutionary studies. This study utilizes photographs of 39 Gangetic catfishes to evaluate inter-specific phenotypic relationship through geometric morphometrics. PERMANOVA revealed significant relationship (F = 4.50, p < 0.0001) between shape of all the species. Procrustes ANOVA revealed significant relationship between shape and size (F = 17.67, p < 0.0001) and between shape (F = 34.95, p < 0.0001) of all species. The first two principal components of PCA accounted for 69.41% (PC1 44.41% and PC2 25.00%) of the total variance while the first two canonical variates of CVA accounted for 55.89% (CV1 34.06% and CV2 21.83%) of the total variance. The CVA-extracted Mahalanobis and Procrustes distances were found to be highly significant (p < 0.0001) between distinct groups and non-significant (p > 0.0001) between closely related groups. Morphospace phenogram depicted that the species under Mystus, Sperata, Glyptothorax, Ompok, Eutropiichthys, Bagarius and Gagata clustered together in their respective genus, indicating that species of respective genus share common phenotypic traits and have evolutionary relatedness. Species like Chaca chaca, Clarias magur, Sisor rabdophorus, Heteropneustes fossilis, Silonia silondia and Clupisoma garua showed clear distinctness, which may be attributed to different set of morphological traits. The study affirms the implication of geometric morphometrics in discriminating Gangetic catfishes and showcasing phenotypic relatedness between respective groups. This study has high implications in understanding the ecological and evolutionary problems in relation to morphological diversity in catfishes.