Phenotypic disparity in the Schizothorax richardsonii of different geographic regions of the Lesser Himalayas

Abstract

The intraspecific variation of Schizothorax richardsonii was estimated by analysing the morphometric characters. Schizothorax richardsonii is an indigenous Himalayan fish species, generally dwelling in fast flowing snow-fed rivers (8-22°C), streams and lakes and contributes significantly to the cold water fishery in the Himalayan region. Specimens were collected from five sampling sites including four natural lotic water bodies of the state Uttarakhand and one farmed stock of the target fish that is Kosi River, Alaknanda River, Chirapani stream, Gaula River and captive stock of DCFR Farm, Bhimtal. Phenotypic study was performed using Truss Network of 14 landmarks making 31 characters which reported high degree of significant morphometric heterogeneity among the populations with size within landmarks and shape as major factors of divergence in the selected ecosystems. Between-groups Principal Component Analysis revealed that the first and second principal components accounted for 91.2% and 5.4% of variance respectively. 94.5% of original grouped cases were correctly classified each original group for morphometric measurements of S. richardsonii and formed separate clusters. The results revealed that the candidate species has significant phenotypic heterogeneity between the stocks. We hypothesize that the marked variation in the stock is supporting the fact that environment plays a vital role in shaping the phenotypic characters.