Borchiellini C, Manuel M, Alivon E, Boury-Esnault N, Vacelet J, Le Parco Y
Centre d'Océanologie de Marseille, Station Marine d'Endoume, Université de la Méditerranée, UMR-CNRS 6540, Marseille, France.
J Evol Biol. 2001 Jan 8;14(1):171-179. doi: 10.1046/j.1420-9101.2001.00244.x.
In order to allow critical evaluation of the interrelationships between the three sponge classes, and to resolve the question of mono- or paraphyly of sponges (Porifera), we used the polymerase chain reaction (PCR) to amplify almost the entire nucleic acid sequence of the 18S rDNA from several hexactinellid, demosponge and calcareous sponge species. The amplification products were cloned, sequenced and then aligned with previously reported sequences from other sponges and nonsponge metazoans and variously distant outgroups, and trees were constructed using both neighbour-joining and maximum parsimony methods. Our results suggest that sponges are paraphyletic, the Calcarea being more related to monophyletic Eumetazoa than to the siliceous sponges (Demospongiae, Hexactinellida). These results have important implications for our understanding of metazoan origins, because they suggest that the common ancestor of Metazoa was a sponge. They also have consequences for basal metazoan classification, implying that the phylum Porifera should be abandoned. Our results support the upgrading of the calcareous sponge class to the phylum level.
为了能够对三个海绵纲之间的相互关系进行批判性评估，并解决海绵动物（多孔动物门）是单系类群还是并系类群的问题，我们使用聚合酶链反应（PCR）扩增了几种六放海绵纲、寻常海绵纲和钙质海绵纲物种的18S核糖体DNA（rDNA）几乎完整的核酸序列。扩增产物被克隆、测序，然后与先前报道的其他海绵动物、非海绵后生动物以及不同远缘外类群的序列进行比对，并使用邻接法和最大简约法构建系统树。我们的结果表明，海绵动物是并系类群，钙质海绵纲与单系的真后生动物的关系比与硅质海绵（寻常海绵纲、六放海绵纲）的关系更为密切。这些结果对于我们理解后生动物的起源具有重要意义，因为它们表明后生动物的共同祖先是一种海绵。它们对基础后生动物分类也有影响，意味着多孔动物门应该被摒弃。我们的结果支持将钙质海绵纲提升到门的分类水平。
