Evaluation of genetic relationship among six Labeo species using randomly amplified polymorphic DNA (RAPD)

Labeo species constitute an important group of fish with intense diversity and potential for commercial aquaculture in many Southeast Asian nations including the Indian subcontinent. The present investigation involves the comparative analysis of randomly amplified polymorphic DNA (RAPD) profiles of six Labeo species viz., L. bata (bata), L. calbasu (calbasu), L. dyocheilus (dyocheilus), L. fimbriatus (fimbriatus), L. gonius (gonius) and L. rohita (rohu) at the nuclear DNA variation level. Fifteen decamer random primers were chosen from 40, which amplified a total of 449 DNA fragments ranging in size from 400 to 3000 bp. Both monomorphic and polymorphic DNA bands were identified based on their presence or absence that could be used for specieswise differentiation. Similarity coefficients were calculated to quantify the genetic variation within and between species. On an average, the highest intra-species genetic similarity value was found in calbasu (0.93) followed by rohu and fimbriatus (0.91), bata (0.87), gonius (0.86) and dyocheilus (0.77). The interspecies genetic similarity estimates among the species of Labeo were used to deduce their phylogenetic relationships. The cluster analysis showed two main clusters, one with calbasu, rohu, fimbriatus and gonius and another with bata and dyocheilus. The study provides evidence that RAPD could be used for genetic differentiation of closely related species.