Accumulation of gene copy number variations during the early phase of free-spawning abalone speciation

<p><span>The g</span><span>enetic basis of speciation in free-spawning marine invertebrates is poorly understood. Although gene copy number variations (GCNVs) as well as nucleotide variations possibly trigger the speciation of these organisms, empirical evidence for such </span><span>a hypothesis</span><span> is limited. In this study, we searched for genomic signatures of GCNVs that may contribute to the speciation of Western Pacific abalone species. Whole-genome sequencing data suggested the existence of significant amounts of GCNVs in closely related abalones, <em>Haliotis discus</em> and <em>H. madaka</em>, in the early phase of speciation. In addition, the degree of interspecies genetic differentiation in the genes where GCNVs were estimated was higher than </span><span>that </span><span>in other genes, suggesting that nucleotide divergence also accumulate</span><span>s in the genes with GCNVs.</span><span> GCNVs in some genes were also detected in other related abalone species, suggesting that these GCNVs are derived from both ancestral and <em>de novo</em> mutations.</span> <span>Our findings </span><span>suggest that GCNVs have been accumulated in </span><span>the early phase</span><span> of free-spawning abalone speciation.</span></p>