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

点击翻译按钮获取中文摘要

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.