Phylogenomics, Classification, and Revisionary Studies of Meniscus Midges (Diptera: Dixidae)

水生昆虫是营养加工和水质净化的贡献者，是生态研究和环境监测与评估的模式生物，也是脊椎动物捕食者的猎物。作为后者的结果，许多被视为休闲捕鱼中人工诱饵(即“苍蝇”)的诱饵或模型。双翅目，或“真蝇”，构成了水生昆虫多样性的很大一部分。Dixidae，俗称“半月板吸虫”，是本研究的重点。这些类似蚊子的苍蝇最为人所知的是它们独特的幼虫，它们适应于生活在浮生岩石或植被周围的空气-水界面(因此而得名)。人们经常看到它们在水面上横向游泳，或者以特有的U型姿势休息。与相关类群相比，Dixidae受到的科学家关注要少得多。这在一定程度上是因为缺乏医学上的重要性，以及缺乏研究该家族的分类学专家。此外，历史上对Dixidae的研究一直集中在地区性动物群上，而不是全球更全面的治疗方法，导致我们的知识存在很大差距。因此，Dixidae的分类令人困惑和难以分辨，对大多数物种的自然历史知之甚少。如果不加以纠正，这一泥潭将严重阻碍未来对该家族的研究。这个解决方案是基于综合的形态和分子系统发育研究结果，对目前的世界Dixidae分类进行彻底的修改。更深入地了解二氧嘧啶的进化不仅本身很重要，而且很有价值，因为它有助于洞察它们的食血进化，以及它们的瘟疫亲戚：蚊子、黑蝇和叮咬的蚊子。在与普通和分子生物学、生物信息学和系统发育学相关的当前和新兴技术方面，对学生和早期职业科学家的广泛培训将被纳入本研究，以便他们能够应对21世纪生物学家面临的快速发展的挑战。一个可靠的系统发育假说将大大有助于稳定Dixidae的分类和公布未来的研究。这项研究所需的标本将通过博物馆出借和必要的田野调查获得。目前的分类困境和公众对该科极其有限的认识将通过完成以下研究和推广目标来解决：(1)利用形态和系统学相结合的方法，对整个科(Tier 1：超种群)和目标亚支(Tier 2：新北界属Dixa和Amp；Dixella，冈德瓦南属Nothodixa)进行彻底的系统修订，前者收集自卵后的所有生活期，后者的DNA序列代表核基因组中的数百个基因；这些研究将产生基于形态(二分和多通道检索表、高分辨率摄影图像、详细插图、交互式三维模型)和基于分子(原始数据、序列比对、系统发育推论)的结果；(2)开发DNA指纹资源，包括线粒体和核，以便能够快速、可靠地识别世界物种；(3)改进和完成一种新的方法，利用参考作图方法以及伴随的绘制前后生物信息学管道，从短读基因组库中挖掘系统发育信息标记，所有这些都打算在用户友好的图形用户界面(图形用户界面)环境中进行；以及(4)通过面对面和基于互联网的外展计划，培养对科学方法、批判性思维和自然科学的欣赏，使用水生昆虫作为模式生物，吸引主要缺乏服务的年轻人，否则他们可能很少接触科学。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Aquatic insects are contributors to nutrient processing and water purification, serve as model organisms in ecological research and environmental monitoring and assessment, and are prey items for vertebrate predators. As a consequence of the latter, many are valued as bait or models for artificial lures (i.e., “flies”) in recreational fishing. Order Diptera, or “true flies”, comprises a substantial portion of aquatic insect diversity. Dixidae, one such family commonly known as “meniscus midges”, are the focus of this study. These mosquito-like flies are best known for their unique larvae, which are adapted to live at the air-water interface (hence the common name) surrounding emergent rocks or vegetation. They are often seen swimming laterally on the water’s surface or resting in a characteristic U-shaped posture. Dixidae, when compared to related groups, have received far less attention from scientists. This is due in part to the lack of medical importance and a paucity of taxonomic experts for the family. Furthermore, studies of Dixidae have historically focused on regional faunas, rather than global, more comprehensive treatments, leading to large gaps in our knowledge. As a result, the taxonomy of Dixidae is confusing and poorly resolved, and relatively little is known about the natural history of most species. If left uncorrected, this quagmire represents a serious impediment to future research on the family. The solution is a complete overhaul of the current classification of world Dixidae based upon results of an integrative morphological and molecular phylogenetic study. A greater understanding of dixid evolution is not only important in its own right, but also valuable because it lends insight into the evolution of their blood feeding, pestiferous relatives: mosquitoes, black flies, and biting midges. Extensive training of students and early career scientists in current and emerging technologies with relevance to general and molecular biology, bioinformatics, and phylogenetics will be incorporated throughout this study so they will be poised to meet rapidly developing challenges facing 21st century biologists. A robust phylogenetic hypothesis will significantly aid in stabilizing the classification of Dixidae and promulgating future research. Specimens needed for this study will be acquired through museum loans and necessary fieldwork. The current taxonomic quandary and the extremely limited public awareness of this family will be remedied by completing the following research and outreach objectives: (1) complete thorough systematic revisions of the entire family (Tier 1: supraspecific groups) and targeted subclades (Tier 2: Nearctic genera Dixa & Dixella, Gondwanan genus Nothodixa) using a combined morphological and phylogenomic approach, the former gleaned from all life stages after the egg and the latter DNA sequences representing hundreds of genes from the nuclear genome; these studies will yield morphology-based (dichotomous and multi-access keys, high-resolution photographic images, detailed illustrations, interactive 3-D models) and molecular-based (raw data, sequence alignments, phylogenetic inferences) outputs; (2) develop DNA-fingerprinting resources, both mitochondrial and nuclear, to allow for rapid, reliable identification of world species; (3) refinement and completion of a novel approach to mine phylogenetically informative markers from short-read genomic libraries using a reference mapping approach as well as accompanying pre- and post-mapping bioinformatics pipelines, all of which are intended to be carried out within a user-friendly graphical user interface (GUI) setting; and (4) through in-person and internet-based outreach programs, foster an appreciation for the scientific method, critical thinking, and natural sciences using aquatic insects as model organisms, engaging predominantly underserved youths who may otherwise receive little exposure to science.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.