Systematics and Evolution of Pedipalpi (Whip Spiders and Whip Scorpions): Phylogenomics and Morphology of Understudied Arachnids

American Museum Natural History, New York NY

Investigators

Abstract

Pedipalpi is a lineage comprising three little known groups of arachnids: Amblypygi (whip spiders), Schizomida (short-tailed whip scorpions or micro-whip scorpions), and Thelyphonida (vinegaroons or whip scorpions). These nocturnal predators, which inhabit tropical and subtropical habitats on all major landmasses except Antarctica, are important for controlling insect populations and have hardly changed anatomically in 300 million years. What little is known about their life history and behavior reveals complex courtship rituals, male combat, territoriality, sociality, parental care, and chemical defense with an arsenal of noxious defense secretions. Despite the deep evolutionary timescale, global distribution, ecological importance, and fascinating life history and behavior of Pedipalpi, little progress on their classification has been made in a century, and their branch of the Tree of Life is barely assembled, hindering the testing of hypotheses concerning their evolution. By leveraging technological advances in genomics, microscopy, imaging, and informatics, and integrating anatomical and genomic data, this project will build the first comprehensive tree of life for living and fossil Pedipalpi, train a new generation of experts on these poorly studied arachnids, and disseminate results to the public. Two Ph.D. students and two postdoctoral associates, from groups under-represented in science, will be supported. Each year, an undergraduate, two high school students, and two citizen scientists will be involved in research. Courses on the biology and classification of Pedipalpi, 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 at meetings, online, and via nationally distributed classroom magazines. The project has four primary aims. (1) Using a high-throughput, targeted enrichment approach, ca. 100,000 base-pairs of DNA sequence, per specimen, will be generated for representatives of all major lineages, 70% of the genera, and 30% of the species of living Pedipalpi. (2) A matrix of morphological observations will be compiled for all species in the genomic dataset and representatives of extinct lineages of Pedipalpi and their chelicerate relatives. The phylogeny and morphology will be used to (3) present a predictive classification of Pedipalpi above the level of genus and conduct monographic taxonomic revisions of four lineages, and (4) investigate questions concerning the evolution and diversification of Pedipalpi. How, when, and where did the major lineages of Pedipalpi diversify, and which key innovations enabled them to do so? Is morphological specialization to life in caves, commonly inhabited by Pedipalpi, an irreversible, evolutionary dead-end? Is sexual dimorphism in the spinose pedipalps (claws) of Amblypygi ancestral or derived, and did it evolve to reduce injury in ritualized male combat, or was it sexually selected? 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.