Phenotypic Plasticity and Genetic Variation of Two Wild Populations of Green tiger Shrimp (<i>Penaeus semisulcatus</i> - De Haan, 1844)

Abstract

Utility of wild-caught brood stocks in shrimp farming industry is still practiced in many countries. Therefore, identification of genetic variability of geographically distributed commercially important species provide useful information that could be utilized in aquaculture programs. This study investigated the morphological and genetic variation between two wild populations of P. semisulcatus from Northern and Southern parts in Sri Lanka. Each population was consisted with 70 individuals and forty two measurements were taken according to the truss network system for morphometric study. Discriminant function analysis identified four parameters as significant contributors to discriminate two populations and they were associated with the abdominal region of P. semisulcatus . Altogether 3280 nucleotides were analyzed representing four mitochondrial and two nuclear gene regions (both coding and non-coding). Results indicated low genetic variation between two populations. Mitochondrial control gene region produced seven haplotypes which were common between two populations (nucleotide divergence ranged from 0.8% to 5.2%). Among three haplotypes resulted from Cytochrome Oxidase I gene region (COI), one haplotype was common between two populations (nucleotide divergence ranged from 0.1% to 0.3%). Other two mitochondrial gene regions (16S rRNA & 12S rRNA) and two Nuclear (18S RNA & H3) gene regions produced single shared haplotype for each region. In conclusion, results suggest the phenotypic fixation to environmental conditions indicating phenotypic plasticity in P. semisulcatus populations in northern and southern parts of the island.