The rise of heterobranchs (Gastropoda) – comparative microanatomy and early evolution

异分支（腹足纲）的兴起——比较显微解剖学和早期进化

• 批准号: 419974396
• 负责人: Dr. Bastian Brenzinger
• 金额: --
• 依托单位: Zoologisches Institut und Museum
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/419974396?language=en
• 关键词: rise; heterobranchs; Gastropoda; comparative; microanatomy

Combined strategies of genetics and morphology have the potential to subsequently reconstruct the evolution of life. Heterobranch gastropods (class Heterobranchia) are one of the two largest gastropod clades and by this also of Mollusca. However, the origin of derived and by far most diverse diverse, ubiquitous subclade Euthyneura is still obscure. Since the 1980's, about a dozen families of poorly known, mostly small-bodied and marine shelled snails have been identified as links between Euthyneura and the remaining Gastropoda including similarly diverse Caenogastropoda. However, due to a presently insufficient coverage by integrative studies, relationships of these phylogenetically so important so-called "lower" heterobranch families remain almost unsolved and little comparative anatomical or other biological data are available to substantiate any phylogenetic hypotheses on Euthyneura and Heterobranchia. In the present project, I aim to solve this problem by combining the expertise of highly experienced laboratories in Munich, Harvard, and Tokyo and to use detailed microanatomical studies based on high-resolution (histology and CT-based) 3D-reconstruction together with state-of-the-art phylogenomic and Sanger-sequencing-based phylogenetic reconstruction methods. Our present taxon sampling is derived from international collecting efforts spanning several years and already covers all of familial and over half the generic diversity of lower Heterobranchia. Preparative work was the often first-time sequencing of the barcoding gene COI for about 100 samples of all families, the sequencing of novel transcriptomes covering most families, and the compiling of taxonomic expertise, material for anatomical examination and partial 3D-reconstructions for 12 families identified as understudied and phylogenetically relevant for the scope of this project.By this we expect to fully solve early phylogeny of Heterobranchia within three years, and to support this new “heterobranch backbone tree” by comprehensive microanatomical data of all organ systems usable for large-scale comparative anatomy. We expect to shed light on how heterobranch organs so drastically changed morphology during the early 400 years of their evolution, thereby using lower Heterobranchia to link such shelled taxa and their fossil representatives to outgroup Caenogastropoda and derived Euthyneura, the latter including the majority of biologically much better-known and ecologically relevant seaslugs and stalk-eyed land snails. We believe our approach to have large explanatory potential for understanding biology and evolution in either of these species-rich groups, together forming almost 60% of mollusk diversity.

遗传学和形态学相结合的策略有可能随后重建生命的进化。异鳃腹足类（Heteroblanchia）是两个最大的腹足类分支之一，也是软体动物门的分支。然而，衍生的和迄今为止最多样化的多样性，无处不在的亚支Euthyneura的起源仍然是模糊的。自20世纪80年代以来，大约有十几个鲜为人知的家庭，大多数是小型和海洋贝类蜗牛已被确定为Euthyneura和其余的腹足类之间的联系，包括类似的不同Caenogastropoda。然而，由于目前的综合研究覆盖面不足，这些在遗传学上如此重要的所谓的“较低”的异鳃科的关系仍然几乎没有解决，很少有比较解剖学或其他生物学数据可用于证实任何系统发育假说真脊神经和异鳃类。在本项目中，我的目标是解决这个问题，结合经验丰富的实验室在慕尼黑，哈佛，东京的专业知识，并使用详细的显微解剖研究的基础上，高分辨率（组织学和CT为基础的）三维重建与国家的最先进的基因组和桑格测序为基础的系统发育重建方法。我们目前的分类群采样来自国际收集努力跨越几年，已经涵盖了所有的家庭和一半以上的属的多样性较低的异鳃类。成果性的工作通常是首次对所有科的约100个样本的条形码基因COI进行测序，对涵盖大多数科的新型转录组进行测序，以及汇编分类学专业知识，用于解剖检查和部分3D的材料-重建12个家庭确定为研究不足，并与本项目的范围遗传相关。通过这一点，我们希望完全解决早期的遗传问题，Heterobranchia在三年内，并支持这一新的“heterobranchia骨干树”的全面显微解剖数据的所有器官系统可用于大规模的比较解剖。我们希望阐明如何heterobranchia器官如此剧烈地改变形态，在其早期400年的进化，从而使用较低的Heterobranchia连接等带壳类群和他们的化石代表外组新腹足类和衍生Euthyneura，后者包括大多数生物学上更好地了解和生态相关的海蛞蝓和茎眼陆蜗牛。我们相信我们的方法对于理解这些物种丰富的群体中的生物学和进化具有巨大的解释潜力，这些群体共同构成了近60%的软体动物多样性。