A highly contiguous genome assembly for the California vole, Microtus californicus, provides insight into phylogenetic relationships and patterns of synteny among voles.

The California vole (Microtus californicus) is a small cricetid rodent and one of 20 species of Microtus in North America and 60 worldwide. Several subspecies are listed as being of conservation concern in California, and one is federally protected. Here we present the first de novo genome assembly for the California vole, generated as a part of the California Conservation Genomics Project. The M. californicus genome was generated using a combination of PacBio HiFi long reads and Omni-C chromatin-proximity sequencing technology. Our high-quality genome is one of the most complete vole assemblies available, with a contig N50 of 49.8 Mb, scaffold N50 of 83.7 Mb, and BUSCO completeness score of 96.4%. Analysis of this genome together with genomes of closely related species revealed phylogenetic relationships and high levels of synteny among voles. The California vole genome provides an important new resource for comparative work across cricetid and muroid genomes. It will also serve as a reference for the analysis of within-species genetic diversity across widespread subspecies as well as more restricted populations of conservation concern.