The complete genomes of two hybridizing field crickets, <i>Gryllus pennsylvanicus</i> and <i>Gryllus firmus</i>

Abstract The field crickets, Gryllus pennsylvanicus and Gryllus firmus, share a well-studied hybrid zone in the eastern US and are a key study system in speciation research. We report the genome assembly for each species using PacBio HiFi long-read sequencing data. We assembled the sequenced reads for G. pennsylvanicus into 2,924 scaffolds totaling 2.1 Gb and for G. firmus into 3,010 scaffolds totaling 2.0 Gb. Using a reference-based protocol, we achieved chromosome-level assemblies comprising 15 chromosomes for each species (totaling 1.86 and 1.84 Gb, respectively). The assemblies were nearly complete, with scaffold N50s of 115.64 and 119.52 Mb, respectively, and BUSCO scores of 97%. We characterized structural variants (SVs) between the two species using both genome assemblies and HiFi sequencing data. The longest SV found was a potential inversion spanning 10.12 Mb along the X chromosome; this inversion may represent a key component of divergence between the two species. Both reference genomes will be essential resources for ongoing studies of the evolution of reproductive isolation and comparative studies across field crickets.