Molecular phylogeny and evolution of the pelagic copepod genus Neocalanus (Crustacea: Copepoda)
Molecular phylogeny and evolution of the pelagic copepod genus Neocalanus (Crustacea: Copepoda)
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DOI：
10.1007/s00227-005-0140-0
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发表时间：
2006-03-01
期刊：
影响因子：
2.4
通讯作者：
Nishida, S
中科院分区：
文献类型：
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作者：
Machida, RJ;Miya, MU;Nishida, S
研究人员对目前已知的6种远海鱿鱼类桡足动物Neocalanus的线粒体基因组部分（约4 kb）进行了测序，其中编码3个蛋白质编码基因（COI, ND4L, ND6）和2个核糖体RNA （srRNA, lrRNA）基因。在新马鞍子中，ND6基因未在线粒体基因组测序部分中发现。明确对齐的序列受到贝叶斯、最大似然、最大简约和邻居连接分析，使用本氏尤卡兰纳斯作为外群。这四种方法得到的树拓扑是一致的、鲁棒的，所有节点都有高自举值和92-100%的后验概率支持。两个热带和亚热带种（N. gracilis和N. routiti）占据了最基础的位置，一个亚南极种（N. tonsus）和三个亚北极太平洋种（N. cristatus， N. plumchrus和N. flemingeri）随后分化。这种物种形成模式表明，在冰川时期祖先种群的跨地区分散，其中姐妹枝表现出反热带分布。虽然亚南极的海洋面积比亚北极太平洋大得多，但亚北极太平洋的物种数量（3种）比亚南极（1种）要多。讨论了日本海、鄂霍次克海等边缘海作为物种分化出生区的可能性。
Portions of the mitochondrial genome (ca. 4 kb), encoding three protein-coding (COI, ND4L, ND6) and two ribosomal RNA (srRNA, lrRNA) genes, were sequenced for all six currently recognized species, plus one form, of the pelagic calanoid copepod genus Neocalanus. In Neocalanus gracilis, the ND6 gene was not found in the sequenced portion of the mitochondrial genome. Unambiguously aligned sequences were subjected to Bayesian, maximum-likelihood, maximum-parsimony, and neighbor-joining analyses using Eucalanus bungii as an outgroup. The resultant tree topologies from these four methods were congruent, robust, and all nodes were supported by high bootstrap values and posterior probabilities of 92-100%. Two tropical and subtropical species (N. gracilis and N. robustior) occupied the most basal position, and a subantarctic (N. tonsus) and three subarctic Pacific species (N. cristatus, N. plumchrus, and N. flemingeri) diverged subsequently. Transequatorial dispersal of the ancestral population during glaciations is suggested for this pattern of speciation, in which sister clades exhibited antitropical distributions. Although the area of ocean is much broader in the subantarctic than the subarctic Pacific, a higher number of species occur in the subarctic Pacific (three) than the subantarctic (one). The possibility that marginal seas, such as Japan Sea and Okhotsk Sea, function as natal areas for the divergence of species is discussed.