Chromosome-Level Assembly of the Genome Reveals Conserved Patterns of Nematode Genome Organization.

The nematode is one of the key model systems in biology, including possessing the first fully assembled animal genome. Whereas is a self-reproducing hermaphrodite with fairly limited within-population variation, its relative is an outcrossing species with much more extensive genetic variation, making it an ideal parallel model system for evolutionary genetic investigations. Here, we greatly improve on previous assemblies by generating a chromosome-level assembly of the entire genome (124.8 Mb of total size) using long-read sequencing and chromatin conformation capture data. Like other fully assembled genomes in the genus, we find that the genome displays a high degree of synteny with despite multiple within-chromosome rearrangements. Both genomes have high gene density in central regions of chromosomes relative to chromosome ends and the opposite pattern for the accumulation of repetitive elements. and also show similar patterns of interchromosome interactions, with the central regions of chromosomes appearing to interact with one another more than the distal ends. The new genome presented here greatly augments the use of the as a platform for comparative genomics and serves as a basis for molecular population genetics within this highly diverse species.