Joseph Sneha, Vakani Bhavik, Kundu Rahul
a Department of Bioscience , Saurashtra University , Rajkot , Gujarat , India.
Mitochondrial DNA A DNA Mapp Seq Anal. 2018 Mar;29(2):181-191. doi: 10.1080/24701394.2016.1261854. Epub 2016 Dec 26.
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.
利用分子系统发育学，对一组表现出表型可塑性的卡拉奇笠贝（Cellana karachiensis）进行了研究，这些笠贝采自印度古吉拉特邦海岸线。先前对细胞色素氧化酶亚基I（COI）基因的检测确定存在三种不同的单倍型X、Y和Z，而本研究显示又出现了三种单倍型X、X和Z。因此，共观察到六种COI基因单倍型，序列相似性为99.23%至99.85%，在六个位点存在变异。贝叶斯系统发育分析显示谱系X - Y、X - X和Z - Z存在分歧。对核苷酸变化的仔细观察表明，在卡拉奇笠贝属的近缘物种之间存在非随机突变，A↔G和C↔T转换更为常见。在COI区域内，一段17个碱基对的片段被标记为卡拉奇笠贝属物种间高度可变的区域。结果表明，这可能是物种形成的开端，伴有部分或完全的生殖隔离，或者这些已经是处于不同进化阶段的不同物种。
