Comparative genomics reveals the dynamic evolutionary history of cement protein genes of barnacles from intertidal to deep-sea hydrothermal vents

Thoracican barnacles are a diverse group of marine organisms for which the availability of genome assemblies is currently limited. In this study, we sequenced the genomes of two neolepadoid species (Ashinkailepas kermadecensis, Imbricaverruca yamaguchii) from hydrothermal vents, in addition to two intertidal species. Genome sizes ranged from 481.5 to 1054.6 Mb, with repetitive sequence contents of 21.2 to 50.7%. Concordance rates of orthologs and heterozygosity ratios were between 82.4 and 91.7% and between 1.1 and 2.6, respectively, indicating high genetic diversity and heterozygosity. Based on phylogenomic analyses, we revised the nomenclature of cement genes encoding cement proteins that are not homologous to any known proteins. The major cement gene, CP100A, was found in all thoracican species, including vent-associated neolepadoids, and was hypothesized to be essential for thoracican settlement. Duplicated genes, CP100B and CP100C, were found only in balanids, suggesting potential ...