The Malabar mahseer, Tor malabaricus, is a large-bodied freshwater fish native to the monsoonal rivers of Kerala. It is widely used as food and young ones serve as ornamental fish. However, the fish is endangered as per the International Union for Conservation of Nature. Found mainly in the fast flowing streams of the southern Western Ghats, the species’ habitats need to be identified and conserved.
Recently, scientists from the Kerala University of Fisheries and Ocean Studies, at Panangad, Kochi sequenced the complete mitochondrial genome of T. malabaricus to remove the taxonomic ambiguity of its classification within the mahseer group.
The team collected specimens from the Periyar River in Idukki, Kerala. They isolated and amplified DNA from the mitochondria to sequence it. The team reports that the circular mitochondrial genome of T. malabaricus had 16,580 base pairs that contained thirteen protein coding genes, twenty-two tRNA genes, two rRNA genes and one region to control the genes.
The scientists compared the mitochondrial genome sequences of nine mahseer species available in GenBank, an open-access genetic sequence database. With the help of thirteen protein-coding genes, they computed nucleotide base compositions and molecular evolution to construct phylogenetic trees – diagrams representing evolutionary relationships. The team thus confirm that T. malabaricus is a distinct species, closely related to the black mahseer, T. khudree. This eliminates a confusion derived from the last century, when T. malabaricus and T. khudree were seen as different names for the same species.
The scientists say that the complete mitochondrial genome sequence of the Malabar Mahseer would help better understand its molecular systematics and evolution. Such information could also help conservation efforts.
Conservation Genetics Resources, 11 (2): 185-189 (2019)
Freelance writer, Cuttack
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