Department of Biology, University of Bergen, Bergen, Norway.
PLoS One. 2011 Apr 8;6(4):e18318. doi: 10.1371/journal.pone.0018318.
The Astrophorida (Porifera, Demospongiae(p)) is geographically and bathymetrically widely distributed. Systema Porifera currently includes five families in this order: Ancorinidae, Calthropellidae, Geodiidae, Pachastrellidae and Thrombidae. To date, molecular phylogenetic studies including Astrophorida species are scarce and offer limited sampling. Phylogenetic relationships within this order are therefore for the most part unknown and hypotheses based on morphology largely untested. Astrophorida taxa have very diverse spicule sets that make them a model of choice to investigate spicule evolution.
METHODOLOGY/PRINCIPAL FINDINGS: With a sampling of 153 specimens (9 families, 29 genera, 89 species) covering the deep- and shallow-waters worldwide, this work presents the first comprehensive molecular phylogeny of the Astrophorida, using a cytochrome c oxidase subunit I (COI) gene partial sequence and the 5' end terminal part of the 28S rDNA gene (C1-D2 domains). The resulting tree suggested that i) the Astrophorida included some lithistid families and some Alectonidae species, ii) the sub-orders Euastrophorida and Streptosclerophorida were both polyphyletic, iii) the Geodiidae, the Ancorinidae and the Pachastrellidae were not monophyletic, iv) the Calthropellidae was part of the Geodiidae clade (Calthropella at least), and finally that v) many genera were polyphyletic (Ecionemia, Erylus, Poecillastra, Penares, Rhabdastrella, Stelletta and Vulcanella).
The Astrophorida is a larger order than previously considered, comprising ca. 820 species. Based on these results, we propose new classifications for the Astrophorida using both the classical rank-based nomenclature (i.e., Linnaean classification) and the phylogenetic nomenclature following the PhyloCode, independent of taxonomic rank. A key to the Astrophorida families, sub-families and genera incertae sedis is also included. Incongruences between our molecular tree and the current classification can be explained by the banality of convergent evolution and secondary loss in spicule evolution. These processes have taken place many times, in all the major clades, for megascleres and microscleres.
Astrophorida（多孔动物门，海绵动物门（Demospongiae(p)））在地理和水深上分布广泛。目前，系统多孔动物门在这个目中包括五个科：Ancorinidae、Calthropellidae、Geodiidae、Pachastrellidae 和 Thrombidae。迄今为止，包括 Astrophorida 物种在内的分子系统发育研究很少，采样有限。因此，该目中的系统发育关系在很大程度上是未知的，基于形态的假说也未经充分检验。Astrophorida 类群具有非常多样化的骨针集，使它们成为研究骨针进化的首选模型。
方法/主要发现：本研究使用细胞色素 c 氧化酶亚基 I（COI）基因部分序列和 28S rDNA 基因的 5'末端末端部分（C1-D2 结构域）对来自全球深水区和浅水区的 153 个标本（9 科、29 属、89 种）进行了抽样，这是首次对 Astrophorida 的全面分子系统发育研究。结果表明：i）Astrophorida 包括一些 Lithistid 科和一些 Alectonidae 物种，ii）亚目 Euastrophorida 和 Streptosclerophorida 均为多系群，iii）Geodiidae、Ancorinidae 和 Pachastrellidae 不是单系群，iv）Calthropellidae 是 Geodiidae 科群的一部分（至少包括 Calthropella），最后，v）许多属是多系群（Ecionemia、Erylus、Poecillastra、Penares、Rhabdastrella、Stelletta 和 Vulcanella）。
Astrophorida 是一个比以前认为的更大的目，包括约 820 种。基于这些结果，我们使用基于经典等级的命名法（即林奈分类法）和遵循 PhyloCode 的基于系统发育的命名法，对 Astrophorida 提出了新的分类，与分类等级无关。还包括 Astrophorida 科、亚科和未确定属的分类法。我们的分子树与当前分类之间的不一致可以用趋同进化和骨针进化中的次生损失的平凡性来解释。这些过程在所有主要分支中都发生了很多次，涉及大骨针和微骨针。
