Analysis of genetic variation in green chromide [Etroplus suratensis(Bloch)] (Pisces: Cichlidae) using microsatellites and mitochondrial DNA

The cichlid fish, Green Chromide [Etroplus suratensis(Bloch)] is an economically valuable food fish and a preferred candidate for brackishwater aquaculture in India. Genetic variation of E. suratensis collected from 11 different geographic locations of Kerala state, India was investigated using microsatellite and mitochondrial DNA markers [cytochrome c oxidase 1 (CO1) and 16S rDNA genes]. Seventeen primers published for two cichlid species were tested to amplify homologous microsatellite loci in E. suratensis. Six primers yielded successful amplification and only one was found to be polymorphic. Microsatellite analysis revealed a low genetic variation with alleles ranging from 1 to 4. The observed heterozygosity and expected heterozygosity ranged from 0.000 to 0.167 and 0.000 to 0.104. The results showed relatively lower variation in Kayamkulam and Vembanad lake populations. Mitochondrial DNA (CO1) analysis revealed 9 haplotypes with very low haplotype and nucleotide diversity. Genetic differentiation by pairwise F sub(ST) showed that samples from Chandragiripuzha estuary are significantly different from all other populations. AMOVA analysis of both markers indicates significant differentiation between populations. The results of the two markers suggest that the studied 11 populations of E. suratensis showed low genetic variation between populations and leads to the conclusion that they are drawn from the same randomly mating gene pool.