Are meiofaunal species cosmopolitan? Morphological and molecular analysis of Xenotrichula intermedia (Gastrotricha: Chaetonotida)
Are meiofaunal species cosmopolitan? Morphological and molecular analysis of Xenotrichula intermedia (Gastrotricha: Chaetonotida)
复制标题
小型动物物种是世界性的吗？
DOI：
10.1007/bf00349256
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发表时间：
1996
期刊：
影响因子：
2.4
通讯作者：
D. Foltz
中科院分区：
文献类型：
--
作者：
M. Todaro;J. Fleeger;Y. P. Hu;A. Hrincevich;D. Foltz
许多小型底栖动物物种被报道是世界性的，但由于鉴定的不确定性，来自地理上遥远地区的标本与同一物种分类单元的联系是有问题的。在这项研究中，我们研究了从地中海，西北大西洋和墨西哥湾北方的中间异毛藻Remane（Gastrotricha：Chaetonotida）样品的形态和分子变异。单变量分析的16个形态特征是无法检测到人群之间的差异，除了咽的长度，这是显着较短的墨西哥湾标本。典型判别分析分离的墨西哥湾标本从其他两个种群，咽长度贡献了约一半的总歧视。基于限制性片段长度多态性（RFLP）的分子分析，在一个710碱基对的聚合酶链反应（PCR）produet代表大约一半的线粒体细胞色素氧化酶I（COI）基因检测到四个单倍型：一个来自地中海和墨西哥湾的人口和两个共存的大西洋人口。每对单倍型组合计算的核苷酸序列差异估计值（基于共享片段的比例）范围为5.3%至11.5%。高遗传分化和无法明确分离的基础上的形态种群表明，不同的单倍型的个体特征是遗传隔离的同胞物种。
Many meiofaunal species are reported to be cosmopolitan, but due to uncertainties of identification, the affiliation of specimens from geographically distant areas to the same species-taxon is problematic. In this study, we examined morphological and molecular variation in samples of Xenotrichula intermedia Remane (Gastrotricha: Chaetonotida) from the Mediterranean Sea, the northwestern Atlantic and the northern Gulf of Mexico. Univariate analysis of 16 morphological traits was unable to detect differences among populations, except for the length of the pharynx, which was significantly shorter in the Gulf of Mexico specimens. Canonical discriminant analysis separated the Gulf of Mexico specimens from the other two populations, with pharynx length contributing about half of the total discrimination. Molecular analysis based on restriction-fragment length polymorphisms (RFLPs) in a 710-base pair polymerase chain-reaction (PCR) produet representing roughly half of the mitochondrial cytochrome oxidase I (COI) gene detected four haplotypes: one each from the Mediterranean and the Gulf of Mexico populations and two coexisting within the Atlantic population. The estimated nucleotide-sequence divergence calculated for each pairwise combination of haplotypes (based on the proportion of shared fragments) ranged from 5.3 to 11.5%. The high genetic divergence and the inability to clearly separate populations based on morphology suggest that individuals characterized by different haplotypes are genetically isolated sibling species.