P. N. White, C. Ewers, J. P. Wares
Prior results suggested an unusual sequence polymorphism in an amylase gene region of the ribbed mussel Geukensia demissa. We used targeted sequencing, spatial analysis of polymorphism data and a high-quality de novo genome assembly to assess the likelihood that this diversity is inherited as a single Mendelian locus. Our results suggest this is likely, and that the frequencies of the dominant allele groups change dramatically along the Atlantic coast of the United States, particularly across Cape Hatteras. The single-copy nature of the sequence being studied was verified through the development of a new reference genome for Geukensia demissa, described here. Although the overall pattern of sequence diversity is atypical, with much higher allelic divergence than is expected given overall genomic diversity, we believe this may be an ecologically valuable molecular marker for study in ribbed mussels.