Living Fossils: Integrating Phylogenomics and Comparative Morphology to Assemble the Scorpion Tree of Life

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Scorpions are dominant arthropod predators in most terrestrial habitats on all major landmasses except Antarctica, and their anatomy has changed very little in the past 435 million years. Every year, 1.2 million scorpion stings cause 3,250 human fatalities worldwide. Scorpion venoms, cocktails of neurotoxins that block nerve impulses, offer great potential for medicine, including treatment of brain cancer and autoimmune diseases, non-addictive painkillers, and ecofriendly insecticides. Despite the antiquity, notoriety, global distribution, ecological, and medical importance of these "living fossils", scorpion classification is contentious and the scorpion tree of life ambiguously resolved, hindering the testing of important hypotheses concerning scorpion evolution, and exploration of the pharmacological potential of scorpion venom. By integrating genomic and morphological data from living and fossil scorpions, this project will provide the most comprehensive analysis of the scorpion tree of life and the evolutionary position of scorpions, to date. The project will support a Ph.D. student and three postdoctoral associates, all from underrepresented groups. Each year, an undergraduate, two high school students, and two citizen scientists will be involved in research. Courses on scorpion biology, classification, and medical importance, with an introduction to the local fauna, will be presented on four continents. New material, data, and images will enhance scientific infrastructure. Results, data, and educational outreach materials will be disseminated online and via nationally distributed classroom magazines.The project has several primary aims. First, using a high-throughput, targeted enrichment approach, approximately 300,000 bases of DNA sequence, per specimen, will be generated for representatives of all major lineages, at least 80% of the genera of living scorpions, and all living orders of Chelicerata. A matrix of morphological observations will be completed for all species in the genomic dataset and representatives of extinct lineages of scorpions and their chelicerate relatives. Additionally, the phylogeny and morphology will be used to present a predictive classification of scorpions above the level of genus and investigate questions concerning the evolution and diversification of scorpions and their venoms. The project will include extensive fieldwork and collaboration with international colleagues and will represent the most comprehensive evolutionary study of any chelicerate group. A greater understanding of how venom has evolved across the scorpion tree of life will provide the necessary data to fine-tune the use of venom in medicine.