苔藓动物的起源与系统发生研究进展—形态学和分子生物学的证据

苔藓动物是后生动物中的一个重要类群。然而，和其它主要后生动物类群相比，长期以来对它的系统学研究却相对滞后。其起源，系统发生地位以及与其它后生物门类之间、其内部各高级分类群间的谱系发生关系一直存在争议。一般认为它是介于原口动物和后口动物之间的过渡类群。但是，近年来的分子系统学研究已经证实了它的原口归属。古生物学资料表明，虽然苔藓动物的大多数类群在奥陶纪已经分化出来，但它在寒武纪却缺乏任何化石记录。另外，苔藓动物起源的时间和方式、其内部各类群间的系统发生关系特别是现生类群和化石类群之间的关系等诸多问题的解决，还有待于大量的形态学和不同的分子数据的进一步积累，并结合其地层分布等各种相关资料进行综合研究。

The origin and systematics of Bryozoa

Bryozoa is an important group of metazoan animals which has received relatively little attention regarding their origin, phylogenetic relationship with other metazoan phyla and its internal phylogeny. Traditionally, the systematic position of the Bryozoa phylum is regarded as transitional between the protostomes and the deuterostomes. Recent combined molecular and morphological studies confirm that the Bryozoa belongs to the lophotrochozoan supergroup of the protostomes. Bryozoa was quite diversified in the Ordovician, but lacked fossil records in the Cambrian. Nevertheless, questions remain open regarding the time and pattern of bryozoan origin, the origin of extant bryozoan groups or their probable relationship with other fossil groups, and the internal phylogeny of the phylum. It is suggested that future studies must place emphasis on synthetic analysis of bryozoan morphology, stratigraphic ranges, and multi-gene systematics.