Molecular phylogenetic study on few morphotypes of a patellogastropod Cellana karachiensis from northern Arabian Sea reveals unexpected genetic diversity.

A group of limpets, Cellana karachiensis, exhibiting phenotypic plasticity were examined from Gujarat coastline India, using molecular phylogeny. Previous examination of the COI genes established the presence of three different haplotypes X, Y and Z, while present study showed three more haplotypes X, X and Z. Thus, a total of six COI gene haplotypes, having 99.23% to 99.85% sequence similarity, were observed with variations at six sites. Bayesian phylogenetic analysis shows divergence of lineages X-Y, X-X and Z-Z. Careful observation of nucleotide alterations showed a nonrandom mutation with more A↔G and C↔T transitions between closely related species of the genus Cellana. A stretch of 17 base pair, within COI region, was marked as region with high degree of variability between species of Cellana. Results suggest that this could be the beginning of speciation, with partial or complete reproductive barrier or these are already distinct species in different stages of evolution.