Re-evaluating taxonomy and distribution patterns of the Xanthophyceae (Stramenopiles)

黄藻是陆地和淡水生态系统中重要的初级生产者，具有生物技术开发的前景。然而，由于缺乏明确的物种界限，存在神秘的物种复合体和广泛的形态可塑性，进一步探索其生态意义和开发的努力受到阻碍。我们假设黄藻比迄今为止认识到的更加多样和丰富。因此，该项目分为两个相互密切联系的任务，（1）澄清新定义的属和种的分类学，（2）进一步调查生境偏好，物种形成过程以及恢复和命名新的物种和谱系的黄色植物。使用高分辨率的分子标记单系实体（种和属）将恢复从以前的神秘种复合体。将对来自培养物保藏中心、个别合作研究人员和在项目期间建立的自己的新分离株的各种培养菌株进行检查，以建立参考序列数据库。利用单系种的概念，当ITS 2，incl.二级结构比较，psbA/rbcL-间隔区，和完整的rbcL序列一致地恢复一个明确的和强大的系统发育结构。黄藻种的名称将被锚定到表位型，由冷冻保存状态的合适参考培养物建立，以满足ICN要求。对于黄藻的物种形成和生态偏好，将测试重新定义的黄藻物种是否适应于相当狭窄的生态位，以及哪些非生物参数塑造了黄藻群落的多样性和分类组成。通过高通量元条形码方法，将在更广泛的范围内研究黄藻科在不同生境和地理区域的多样性和分布模式。大量的环境样品，即来自淡水，土壤和其他陆地栖息地将被检查其分类组成的黄藻群落，采用组靶向扩增子测序产生的配对末端读取在Illumina MiSeq平台。由于黄藻代表了丰富的和重要的一组微生物在土壤中，我们的目标是相关的黄藻种在土壤中的分布模式与土壤基质的理化性质，以测试非生物因素的测试，可能会决定黄藻群落结构在土壤中。通过使用来自相当遥远的地理区域的样本，可以独立于地理分布来测试对某些栖息地的偏好。

Xanthophyceae is a group of algae, important primary producers in terrestrial as well as freshwater ecosystems and promising for biotechnological exploitation. Attempts to further explore their ecological significance and exploitation are, however, hampered by the absence of clear species delimitations, the presence of cryptic species complexes and extensive morphological plasticity. We assume xanthophytes are more diverse and abundant than recognized until now. Therefore, project is divided into two tasks closely interlinked with each other, (1) a clarification of the taxonomy of the group with newly defined genera and species and (2) further investigation of habitat preferences, speciation processes as well as recovering and naming of new species and lineages of xanthophytes. Using high-resolution molecular markers monophyletic entities (species and genera) will be recovered from previous cryptic species complexes. A broad range of culture strains available from culture collections, individual collaborating researchers and own new isolates established also during the project will be examined to build up a database of reference sequences. Using the monophyletic species concept species of Xanthophyceae will be delimitated when the three markers, ITS2 incl. secondary structure comparisons, psbA/rbcL-spacer region, and full rbcL sequences congruently recover a clear and robust phylogenetic structure. Names of the xanthophyte species will be anchored to epitypes, established from suitable reference cultures in cryopreserved state to fulfil ICN requirements. For speciation and ecological preferences of the Xanthophyceae it will be tested whether the re-defined xanthophyte species are adapted to rather narrow ecological niches and which abiotic parameters shape the diversity and taxonomic composition of Xanthophyceae communities. With a high-throughput meta-barcoding approach the diversity and distribution patterns across various habitats and geographical regions of Xanthophyceae will be studied on a broader scale. A large number of environmental samples, i.e. from freshwater, soil and other terrestrial habitats will be examined for their taxonomic composition of xanthophyte communities, employing group-targeted amplicon sequencing generated as paired-ends reads on Illumina MiSeq platforms. Because xanthophytes represent an abundant and important group of microorganisms in soil, we aim to correlate distribution patterns of Xanthophyceae species in soils with the physicochemical properties of their soil substrate in order to test for abiotic factors test that may determine xanthophyte community structures in soil. By using samples from rather distant geographical regions, preferences towards certain habitats can be tested independent of geographical distribution.