南麂列岛中华蛸(Octopus sinensis)形态与遗传多样性分析

MORPHOLOGICAL AND GENETIC DIVERSITY ANALYSIS OF OCTOPUS SINENSIS IN NANJI ISLANDS

2020年6~12月在南麂列岛采捕一种中大型章鱼44只,描述了形态特征,采用多元分析方法分析了形态多样性,并比较了与真蛸的差异,利用线粒体细胞色素氧化酶亚基I(COI)基因序列构建了系统发育树,并计算了Kimura-2-Parameter(K2P)遗传距离。结果表明,此种章鱼形态特征与中华蛸基本一致,而与真蛸存在显著的形态差异:其第二、三对腕的扩大吸盘位于第12~15个吸盘之间,而真蛸则位于第15~19个吸盘之间;茎化腕吸盘数少于真蛸;舌叶指数小于真蛸。主成分分析与判别分析能将真蛸群体显著区分开,判别准确率为100%,而其余四个群体(南麂列岛与三个中华蛸群体)间存在重叠;聚类分析表明南麂列岛群体与中华蛸更近,二者均与真蛸存在较大距离。在遗传多样性分析中,南麂列岛群体单倍型4个,单倍型多样性水平为0.320±0.121,多态位点6个,核苷酸多样性指数为0.00111;系统发育树表明,该群体与中华蛸亲缘关系最近,K2P遗传距离0.14%,而与真蛸复合体其他类型为2.96%~12.11%。因此,从形态和分子水平鉴定南麂列岛章鱼为中华蛸。

Forty-four medium-to large-sized octopuses were collected from Nanji Islands in Zhejiang Province from June to December 2020, and the main morphological characteristics were described. The morphological diversity of this octopus and its differences between O. vulgaris were investigated by multivariate analysis. The cytochrome c oxidase subunit I(COI) sequences were used to calculate the genetic diversity parameters and to construct the maximum likelihood phylogenetic tree. In addition, the Kimura-2-Parameter(K2P) genetic distance was also calculated. Results showed that this octopus was in line with the redescribed O. sinensis in morphological features, while they had some significant differences with O. vulgaris. First, the enlarged suckers on arms 2 and 3 of males were between the 12;and the 15;in population from Nanji Islands, and O. vulgaris were between the 15;and the 19;instead. Secondly, the number of suckers on the hectocotylus of the Nanji Islands group was less than that in O. vulgaris. Thirdly, the male samples from Nanji Islands had a shorter ligula than O. vulgaris. In the principal component and discriminant analysis, O. vulgaris can be clearly distinguished from the other 4 populations with the discrimination ratio of O. vulgaris reaching 100%, while there was overlap among the other 4 groups. And the cluster analysis showed that the population of Nanji Islands was closely related to O. sinensis, both of which had a large distance from O. vulgaris. In genetic diversity analysis, there were four haplotypes in Nanji Islands population, and the diversity of haplotypes(Hd) is 0.320±0.121. Besides, six polymorphic sites were examined, and the nucleotide diversity was 0.001 11. The phylogenetic tree showed that the octopus of Nanji Islands had the closest relationship with O. sinensis. Moreover, the K2P genetic distance between Nanji Islands population and O. sinensis was 0.14%, while among Nanji Islands population and O. vulgaris species complex ranged from 2.96%~12.11%. Therefore, samples from Nanji Islands can be determined as O. sinensis by the morphological and molecular analysis.