Collaborative Research: Cestode phylogeny and genomics

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Tapeworms are parasites that include numerous species of medial and veterinary importance in mammals as well as thousands of species that parasitize essentially all other groups of vertebrate animals. Yet, we know little about the evolution of the major groups of tapeworms. Not only does this hamper our ability to treat tapeworm infections of medical and veterinary importance, but it also limits the use of tapeworms as model parasite systems to help expand our understanding of food web connections and ecosystem health, and to help inform fisheries management practices. This project aims to generate the molecular and morphological data required to substantially expand our understanding of the evolution of tapeworms. In doing so, it will transform tapeworms and their vertebrate hosts into one of the best known host/parasite systems globally, allowing this system to reach its full potential. The training provided to undergraduate, graduate and postdoctoral researchers will equip them with transferable STEM skills. Furthermore, information about tapeworms will be made publicly available on-line to diverse audiences of all ages by creating a key to the major tapeworm groups, developing an e-book version of a children's book on tapeworms, and building upon an existing global cestode database. A recent global survey has identified tapeworm lineages hosted by sharks and rays as central to the diversification of the Cestoda. This class currently comprises 19 orders. Preliminary phylogenetic work suggests that the current ordinal classification of the class substantially underestimates lineage diversity, especially within the groups of elasmobranch-hosted cestodes. The proposed work aims to provide a robust phylogeny of the class based on targeted gene capture of 738 loci for 960 species of tapeworms. Cestode higher-level classification will be revised to reflect monophyletic groups, informed by new morphological and molecular data. The generation of complete genomes for 20 species spanning the approximately 200-million year gap between the cestodes of medical and veterinary importance for which such data are currently available will provide insight into patterns of taxon-specific gene family evolution across cestodes. Genomic analyses have been designed to take advantage of the multiple independent transitions between marine and non-marine habitats, elasmobranch and non-elasmobranch definitive hosts, and invertebrate and vertebrate final intermediate hosts that have occurred over evolutionary time to identify signatures of parallel evolution. Such signatures are anticipated to provide valuable insight into environmental factors that may have played a role in the evolution of parasite systems with complex life cycles.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.