Phylogeny and evolution of Monoplacophora and basal Mollusca reconstructed by morphological and molecular data sets

来自化石的新证据，以及显微解剖学和分子遗传学结果，挑战了教科书上关于主要软体动物类群的起源和关系的知识。素有“活化石”之称的单胎纲可能是了解早期软体动物进化的关键。然而，它们代表了动物领域中最后一个拥有最小序列数据的类别，因此是系统学家最想要的研究对象之一。申请人可以获得提取的优质DNA和三个物种(微毛藻科、新毛藻科、南极洲新毛藻科)的第一个序列，并将搜索更多的物种。该项目将使用1)保守的标准序列标记(完整的18S和28S rDNA和组蛋白3基因)，2)线粒体基因组学(特别是基因排列)，3)HOX基因的调查，以及4)有助于贝壳形成的基因，作为新的标记来分析单平台动物和其他选定的基本软体动物群体成员。相比之下，鲜为人知的基础软体动物的结构将被检查，并将建立一组非常大的形态数据并进行系统发育分析。探索备受争议的底层软体动物的系统发育，将有助于更好地了解软体动物、软体动物外壳和其他器官的起源和进化，如序列重复结构。

New evidences from fossils, as well as microanatomical and molecular genetic results, have challenged textbook knowledge regarding the origin and relationships of major molluscan groups. The Monoplacophora (Tryblidia), which are famous as “living fossils”, could be the key to understanding the early molluscan evolution. However, they represent one of the last classes in the animal realm with minimum sequence data available, and thus are amongst the most wanted study objects by systematists. Extracted quality DNA and first sequences of three species (Micropilina sp., Neopilinidae sp., Laevipilina antarctica) are available to the applicant, and further species will be searched for. The here proposed project shall analyse monoplacophorans and other selected members of basal molluscan groups using 1) conservative standard sequence markers (complete 18S and 28S rDNA and Histone 3 gene), 2) mitochondrial genomics (especially gene arrangements), 3) a survey of hox genes, and 4) genes contributing to shell formation that will be explored as novel markers. Comparatively, structures of poorly known basal molluscs will be examined, and a very large set of morphological data will be established and analyzed phylogenetically. Exploring the hotly debated basal molluscan phylogeny will contribute to a better understanding of the origin and evolution of Mollusca, the molluscan shell, and other organs such as serially repeated structures.