ARTS: Taxonomy and Molecular Systematics of Mesh Web Spiders (Araneae: Dictynidae)

蜘蛛是一类极其多样化的生物，在世界各地的生态系统中发挥着至关重要的作用。尽管它们臭名昭著，也经常引发人们的恐惧，但对于某些蜘蛛群体来说，我们的知识仍然存在巨大的差距。蜘蛛通常被概括为棕色或灰色的小蜘蛛，Dictynidae中的许多蜘蛛都非常五颜六色，最引人注目的可能是它们有趣的分布模式和迷人的生态特征。事实上，蜘蛛生命树的这个“黑暗角落”组成了一个群体，几乎占据了地球上所有的陆地生态系统，并包含了唯一完全水生的蜘蛛物种。虽然一些物种是非常小的地区特有的，但另一些物种是所有蜘蛛物种中分布最广的一些。单一蜘蛛家族内的这种水平的变异显示出作为一个系统来回答广泛的进化和生态问题的相当大的潜力，特别是当它们与特定特征或行为的进化有关时。这个项目旨在解决这群蜘蛛之间的进化关系以及它们在蜘蛛生命树中的相对位置，揭示蜘蛛生命树中最鲜为人知的部分之一。此外，该项目的一个主要目标是培训美国下一代分类专家、生物生物学家和系统学家。网甲科是一个非常多样化的科，嵌套在“马龙状支系”中。由于蜘蛛生命树中的属、属中种和科之间的关系在很大程度上是未知的，在进化的背景下提出有趣的问题的努力受到阻碍。我们的目标是通过创建一个分类学和系统发育的支架，为未来几年的进一步研究打开该群体进化和生态学研究的大门。我们将通过以下方式完成这项工作：1)使用形态数据和下一代测序(NGS)收集的数据修订中等多样性的不寻常属Lathys；2)使用NGS数据确定所有独脚类属的系统发育关系；3)使用NGS数据确定Dictynidae在蜘蛛生命树中的位置。我们将与我们的多国合作者团队一起收集Lathys的标本和全世界所有Dicynidus属的代表。所有标本的标准化图像，包括类型，将使用高分辨率堆叠图像、扫描电子显微镜显微图像和近50个琥珀化石的显微CT扫描来生成，以便进行一致的形态分析。低覆盖率的基因组测序将用于产生分子数据，这些数据将与形态矩阵结合在一起，随后使用贝叶斯推理进行分析。这种方法允许分析组合的形态和分子数据集，这对包含化石分类群至关重要，这随后允许我们使用TIP测年来产生时间校准的系统发育图。我们将在三个分类尺度上分别进行这些分析：Lathys，所有Dicynidae属，和“Marronid支系”。我们将对Lathys的系统发育进行概率推断，以检验Laurasian生物地理假设。最后，将进行祖先状态重建，以检查形态特征以及生态和行为特征的演变，包括水生栖息地协会和狩猎策略。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Spiders are an incredibly diverse group of organisms that play an essential role in ecosystems all over the world. In spite of their notoriety and the fear that they often inspire, huge gaps in our knowledge remain for some groups of spiders. Often generalized as small and brown or grey, many spiders in the family Dictynidae are quite colorful, and are perhaps most notable for their intriguing distributional patterns and fascinating ecological characteristics. In fact, this “dark corner” of the spider tree of life comprises a group that occupies virtually every terrestrial ecosystem on earth and contains the only fully aquatic spider species. While some species are endemic to very small areas, others are some of the most widespread of all spider species. This level of variation within a single family of spiders shows considerable potential as a system for answering a broad range of evolutionary and ecological questions, especially as they relate to the evolution of specific characteristics or behaviors. This project aims to resolve the evolutionary relationships among this group of spiders and their relative position within the spider tree of life, shining a light on one of the most poorly known parts of the spider tree of life. Additionally, a main goal of this project is to train the next generation of taxonomic experts, organismal biologists and systematists in Dictynid spiders in the US. Dictynidae are a hugely diverse family nested within the “marronoid clade”. Because the relationships of the genera, of species in the genera, and the relationship of the family within the spider tree of life, are largely unknown, efforts to ask interesting questions in an evolutionary context are stymied. We aim to open the door to evolutionary and ecological studies of the group by creating a taxonomic and phylogenetic scaffold in support of further research for years to come. We will accomplish this by: 1) Revising the moderately diverse, unusual genus Lathys using morphological data and data gathered from Next Generation Sequencing (NGS); 2) Determining the phylogenetic relationships of all dictynid genera using NGS data; 3) Using NGS data to determine the placement of Dictynidae within the spider tree of life. We will collect both specimens of Lathys and representatives of all dictynid genera worldwide with our multinational team of collaborators. Standardized images from all specimens, including types, will be produced using high-resolution stacked images, SEM micrographs, and microCT scanning of nearly 50 amber fossils to allow for consistent morphological analysis. Low coverage genome sequencing will be used to produce molecular data that will be incorporated with the morphological matrix to subsequently be analyzed using Bayesian Inference. This method allows the analysis of a combined morphological and molecular dataset, paramount for the inclusion of fossil taxa, which subsequently allows us to use tip dating to produce a time-calibrated phylogeny. We will conduct these analyses separately at three taxonomic scales: Lathys, all dictynid genera, and the “marronoid clade”. We will use probabilistic inference on the resulting Lathys phylogeny to test Laurasian biogeographic hypotheses. Finally, ancestral state reconstruction will be conducted to examine the evolution of morphological characters as well as ecological and behavioral characters, including aquatic habitat association and hunting strategy.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.