DNA Barcoding of Freshwater Prawn Species of Two Genera Macrobrachium and Caridina Using mt-COI Gene

Objective: The aim was to barcoding of Macrobrachium and Caridina species through mt-COI gene, and phylogenetic reconstruction based on the degree of genetic variability between species of these two genera.

Methods: Freshwater prawns were collected from few locations in the Cauvery River, Tamil Nadu, India. They were morphologically identified as Macrobrachium lamarrei, Macrobrachium lamarrei lamarroids, Macrobrachium malcolmsonii and Caridina gracilipes. Genomic DNA was isolated and amplification of mt-COI gene was done. The nucleotide divergence and some phylogenetic information were calculated by using MEGA v.6.01 and DAMBE. The phylognetic tree topology were reconstructed by Maximum likelihood model.

Results: The mt-COI gene sequences of these species showed 99-100% similarity. When Macrobrachium species were compared within themselves, they showed higher number of variable amino acid sites (539), which revealed some distance. When Macrobrachium species were compared with Caridina, they showed still higher number of variable amino acid sites (584), which revealed clear discrimination. In the subjected category, the mean value of inter-general divergence was more (6.934%) than that of the intra-general divergence (within Macrobrachium species, 3.628%; within M. lamarrei, 3.132%; within Caridina, 2.697%). When both subjected and retrieved species of these two genera were pooled together, the mean inter-general divergence value was also more (3.260%) than that of the intra-general divergence (Macrobrachium, 2.080%; within M. lamarrei, 1.222%; within Caridina, 2.200%). Therefore, the sequences of these two genera are more conserved as they showed 3.260-6.934% mean divergence or less subjected to evolutionary forces.

Conclusion: The species of Macrobrachium, and Caridina are clearly delineated from each other as the phylogenetic information obtained through mt-COI partial gene sequences are more conserved and less subjected to evolutionary forces, and thus, their species are genetically distinct.