PHYLOGENETIC RELATIONSHIP OF Amblypharyngodon mola (DANIONINAE) AND Labeo bata (CYPRININAE) BY CYTOCRHOME b GENE SEQUENCE ANALYSIS

Abstract

Amblypharyngodon mola, locally known as “Mola” and Labeo bata, as “Bata” are fish of small indigenous species (SIS), belonging to subfamily Danioninae and Cyprininae, family Cyprinidae. Now a days both fishes are being considered as high aquaculture potential in Bangladesh. Hence, attempt was taken to reveal the evolutionary relationship of both species by using partial sequences of mitochondrial gene Cytochrome b (Cyt b). Sequences were amplified through PCR and submitted to the NCBI Genbank database after determined the final consensus size through multiple sequence alignment. The nucleotide sequences of related fishes were also retrieved from the NCBI genebank databases. The analyses were performed using computer software packages MEGA (Version 6.01). The length of consensus Cyt b were 357, 364 and 356 bp in A. mola, L. bata and A. testudineus respectively. The Transition/Transversion bias (R) was 0.91, where the rate of transitional substitution from A to G, T to C, C to T, G to A were 5.49, 24.93, 29.19 and 7.82 respectively. The rate of transversional substitution from A to T, A to C, T to A, T to G, C to A, C to G, G to T, G to C were 4.37, 4.37, 4.77,4.77, 3.07 and 3.07 respectively. The highest sequence divergence was found in between A. mola and a marine species Opsarius keta (10.003), and the lowest in between L. bata and a freshwater fishes of Australia Melanotaenia duboulayi (3.516). In Maximum likelihood method, studied taxa were grouped into three clades; clade 1consisted of Danio rerio, M. splendida, O. keta, Barilius bendelisis and L. carbasu; clade 2 formed by including O. bakeri, C. mrigala and L. gonius; clade 3 with M.dubolulayi, where A. mola did not form sister with any taxa. In Neighbour joining tree, three clades were also formed with similar cluster formation. Three clades were also observed in Maximum parsimony (MP) method. Interestingly in MP method A. mola formed clade 1 with B. bendelisis and L. bata. Same as previous two method D. rerio and O. keta formed sister group here. The time tree based on maximum likelihood method showed that there were the least times of divergence in between C. mrigala and L. gonius. There was the highest times of divergence (4.89 MYA) in between D. rerio and outgroup taxa A. testiduneus. The study concluded that A. mola and L. bata showed considerable variation in Cyt b gene sequences. A detailed phylogenetic and evolutionary analyses of entire fishes of the famiy Cyprinidae including more genes such as Cytochrome C Oxidase subunit-I, and nuclear genes are highly required to conserve the gene pools of these fishes