Despite being mostly microscopic or hidden, nematodes significantly impact human lives in is diverse and significant. Just four species of animal parasitic nematodes infect over two billion people worldwide, wile many other species cause severe damage to every kind of crop and livestock we rely upon in our existence. Development of successful measures to control parasites is impossible without good knowledge of their biology and evolution. Within nematodes, parasitism originated many times and under different circumstances. And the questions "how did parasitic nematodes evolve" remains unanswered. The goal of this project is to generate genomic data for understudied lineages of nematodes parasitically and mutualistically associated with various groups of invertebrates, and use these newly generated genomes, in combination with already published transcriptomic and genomic datasets to resolve the multiple points of origin of animal parasitism among terrestrial nematodes. New genomes will be generated using ONT protocols and approaches, assembled using Flye and CANU, and improved using minmap2+Pilon. Additional software will be used for quality control, assembly improvement and annotation, but these can be done on a local machine. Phylogenetic analyses will be done using BUSCO protein coding genes, with only the last step, phylogeny inference, requiring the computational resources of NAISS.