Abstract
Background: Body morphology supposed to underpin wide differences in animal performance that can be used to understand the diversification of characters. Further, identifying the fish population with unique shape due to variations in their morphometric characters enable better management of these subunits. Advanced statistical toolkits of morphometry called truss network system and geometric morphometrics have been increasingly used for detecting variations in morphological traits between subunits of fish populations. The present study was therefore carried out with the objective of determining phenotypically distinct units of freshwater fish Systomus sarana collected from geographically isolated locations.Methods: In the present study, 154 specimens of olive barb, S. sarana were collected from four distantly located rivers covering the northern (Ganga), southern (Godavari), central (Narmada), and eastern (Mahanadi) regions of India. Truss-network system and geometric morphometrics have been utilized. Fourteen landmarks were digitized uniformly on each specimen. In the present study, the truss network system yielded size-corrected morphometric characters that were subjected to univariate and multivariate statistical assessment. Results: Analysis of variance (ANOVA) presented significant differences among 63 out of 90 variables (p<0.05). Truss approach includes principal component analysis (PCA) and discriminant function analysis (DFA) while the geometric approach includes PCA, DFA, canonical variate analysis (CVA), partial least square (PLS), the relative warp (RW), and wireframes. CVA extracted Mahalanobis and Procrustes distances among groups found to be highly significant (p<0.0001). In linear DFA, the overall assignment of correctly classified individuals into their original groups was 86.2% for Ganga, 86.1% for the Godavari, 93.9% for the Narmada, and 92.9% for the Mahanadi population. Conclusions: The results revealed significant variations in the morphometric characters which were reflected in the shape of different body features of the studied populations. Both methods revealed analogous results and significant differences among groups in examined features. Our results suggest that S. sarana shows morphological plasticity across different rivers in India. This study supports the concept that geographical isolation among fish populations can lead to morphological variations.
Morphological plasticity in a wild freshwater fish, Systomus sarana (Cyprinidae) from India: a glimpse through advanced morphometric toolkits
