Chromosome-level genomes and population genomics of periodical cicadas Magicicada septendecim and M. cassini reveal signatures of life-cycle divergence and selection

Periodical cicadas (Magicicada spp.) exhibit synchronized 13- and 17-year emergences, yet genomic resources remain limited for understanding the evolution of their life cycles. We present high-quality genome assemblies and annotations for Magicicada septendecim and M. cassini, two co-occurring species representing distinct evolutionary lineages. To characterize population variation, we generated low-coverage whole-genome resequencing data from 15 individuals per species and used probabilistic population genomic approaches to estimate genetic diversity, population structure, and allele frequency spectra. Comparative analyses incorporating the chromosome-level genome of M. septendecula and the draft genome of M. neotredecim enabled ortholog identification, variant polarization, and evaluation of coding sequence evolution using McDonald–Kreitman–based neutrality indices. These genomic resources provide a foundation for investigating demographic history, selection, and the evolutionary processes underlying periodical life cycles in Magicicada