Evolutionary and taxonomic relationships in loach (Genus: Botia) through molecular characterization in a river of Terai region of West Bengal, India

Abstract

Loaches which are quite near to extinction are high demanding fish species having both ornamental and edible food value. Their identification is difficult due to morphological variation especially amongst Botia lohachata and Botia almorhae. Genetic diversity and molecular phylogeny among six loaches belonging to genus Botia were studied. Cytochrome Oxidase I (COI) gene (655 bp) was amplified using PCR and sequenced. The pairwise genetic distances among Botia species ranged from 0.004 to 0.200. The interspecies Kimura’s 2- parameter pair-wise distance was highest (0.200) between B. modesta and B. lohachata and lowest (0.004) for B. almorhae and B. lohachata. The overall transition/transversion bias is R = 3.084. The phylogenetic tree showed that B. almorhae and B. lohachata formed a monophyletic group (supported by 100% bootstrap value) and then constituted one clade with B. kubotai. Other Asian species B. rostrata, B. striata, B. dario B. modesta and B. macracanthus also contributed to this clade but were distant to native Botia species. It was deduced that loaches need attention towards conservation due to its endangerment and vulnerability status.