DISSERTATION RESEARCH: Phylogenomic insights into the origins and evolution of anticoagulants and bloodfeeding in leeches

抗凝剂是一类有助于防止血液凝固的蛋白质。抗凝剂被广泛报道从吸血水蛭和广泛用于医药和害虫防治。本研究将记录抗凝血剂在水蛭近亲中的存在和进化。在水蛭的直系亲属中发现抗凝血剂将揭示蛋白质的起源，并可能导致发现新的抗凝血化合物。两名代表性不足的市中心高中学生将接受实验室方法的指导和培训。此外，研究人员将根据抗凝血剂的进化，为市中心的高中生制作一个课外教学模块，重点关注自然选择。本研究将重建棘足纲、鳃足纲和水蛭之间的系统发育关系，这将有助于解决关于分段蠕虫进化的长期问题。由此产生的进化框架将用于研究：1)抗凝血剂在棘足纲、支足纲、腰足纲和水蛭中的分布；2)是否有证据表明，水蛭的近亲与水蛭在分支上存在正向选择，这与它们的专一性吸血进化是一致的；3)棘足纲是否是水蛭的姐妹类群；4)舌足纲（喙足纲水蛭）是否具有单系性，与捕食器形态一致。以及群体内部的家庭关系模式。原始材料将在美国和瑞典的实地考察中收集。每个样本的唾液腺将被无菌解剖，然后提取RNA，检查质量，并测序。然后，系统发育学和比较系统发育分析将用于重建关系并测试同源基因之间的正选择证据。

Anticoagulants are a class of proteins that help prevent the coagulation of blood. Anticoagulants are widely reported from blood-feeding leeches and are used extensively in medicine and for pest control. This research will document the presence and evolution of anticoagulants in the closest relatives of leeches. Finding anticoagulants in immediate leech relatives will shed light on the origin of the proteins and may lead to the discovery of novel anticoagulant compounds. Two underrepresented inner-city high school students will be mentored and trained in laboratory methods. Additionally, the researchers will produce an extracurricular teaching module for inner-city high school students focused on natural selection, based on the evolution of anticoagulants. This research will reconstruct phylogenetic relationships among Acanthobdellida, Branchiobdellida, and leeches that will help resolve long-standing questions about the evolution of segmented worms. The resulting evolutionary framework will then be used to investigate: 1) the distribution of anticoagulants within Acanthobdellida, Branchiobdellida, Lumbriculida, and leeches, 2) whether there is evidence of positive selection along the branches from leech relatives to leeches, coincident with the evolution of obligate blood-feeding, 3) whether Acanthobdellida are the sister group to leeches, and 4) whether the Rhynchobdellida (proboscis leeches) are monophyletic in line with feeding apparatus morphologies, and the pattern of family relationships within the group. Source material will be collected on field expeditions within the U.S.A. and Sweden. Salivary glands will be aseptically dissected for each sampled species and then RNA will be extracted, checked for quality, and sequenced. Phylogenomic and comparative phylogenetic analyses will then be used to reconstruct relationships and test for evidence of positive selection among orthologous genes.