网角海绵目(Dictyoceratida)谱系发育与形态发生分析  

PHYLOGENY AND MORPHOGENESIS OF DICTYOCERATIDA (PORIFERA: DEMOSPONGIAE)

作　　者：马俊业[1] 杨群[1] 

机构地区：[1]现代古生物学与地层学国家重点实验室,中国科学院南京地质古生物研究所,南京210008

出　　处：《古生物学报》2007年第4期473-480,共8页Acta Palaeontologica Sinica

基　　金：国家自然科学基金(No40572070);中国科学院南京地质古生物研究所课题(06ZZ011103)联合资助

摘　　要：采用形态和分子数据相结合的方法探讨网角海绵目谱系发育和骨骼形态发生问题。根据11个普通海绵种的18S rRNA序列,结合11个形态与结构特征以及生化和细胞学性状,对网角海绵目的系统发育关系进行综合分析。分子系统学分析表明,网角海绵目及角骨海绵科为单系类群,具有宽口型领细胞室的掘海绵科属于网角海绵目。表型数据显示,网角海绵目内的4个科(Dysideidae,Thorectidae,Irciniidae,Spongiidae)为单系类群。网角海绵目的单系性表明具有等级分化特征的海绵质骨架纤维为同源特征,而领细胞室类型的分化,即宽口型和二咽型领细胞室的分化,是在网角海绵内部类群分化的同时发生的。结合角海绵类及相关类群的化石记录和文中关于网角海绵谱系发育分析推测,早期网角海绵可能主要通过胶原纤维粘附外源碎屑颗粒来支撑内部骨架系统;网角海绵的演化向两个方向发展:①合成多种海绵质纤维取代外源物形成骨架系统(网角海绵和指角海绵);②合成硅质骨针取代外源颗粒构成海绵骨架(现代所有具有骨针的普通海绵)。This study deals with the phylogeny and skeletal morphogenesis of the demosponge Dictyoceratida based on molecular and morphological analyses, the latter including skeletal, biochemical and cytological data. We chose 18S rDNA sequences （two new） from 11 demosponge species and conducted phylogenetic analyses in combination with 11 phenetic characters from the dictyoceratids. The 18S rDNA results suggest that both the Order Dictyoceratida and Family Spongiidae are monoplyletic; Family Dysideidae with eurypylous choanocyte chambers belongs to the Order Dictyoceratida. Phylogeny based on the phenetic data suggests that each of the 4 dictyoceratid families （Dysideidae, Thorectidae, Irciniidae, Spongiidae） is monophyletic. It is suggested that the monophyly of Dictyoceratida indicate that the differentiated spongin fibres, a defining character for the order with increasing complexity, are homologous （Text-figure 5）; furthermore, the differentiation of the choanocyte chambers into two types （eurypylous and diplodal） occurred along with the internal branching event within the Dictyoceratida. Our synthesis of the fossil record and the phylogenetic results of the Dictyoceratida and related groups of Keratosa indicate that the primitive dictyoceratid skeletons might be composed of foreign clastic material embedded by collagenous filaments of the sponges, probably similar to the Neoproterozoic sand-sponges. It is likely that the primitive dictyoceratid skeletons evolved in two directions： ① Some dictyoceratid sponges started to synthesize diverse spongin fibres within the skeleton to replace the external elastic material （Dictyoceratida and Dendroceratida）; ②Other dictyoceratid were able to produce siliceous spicules for constructing their skeletons （all extant demosponges with siliceous spicules）. This hypothesis may be further tested in future investigations.

关 键 词：普通海绵纲 网角海绵目 谱系发育 形态发生 分子古生物学 

分 类 号：Q951[生物学—动物学] Q954