Extensive genomic structural differences and significant genetic divergence between <i>T</i>. <i>adhaerens</i> and <i>H</i>. <i>hongkongensis</i>.

<p>(A) Scaled schematic drawings of the 10 longest <i>T</i>. <i>adhaerens</i> scaffolds on the left (ta1–ta10) and matching <i>H</i>. <i>hongkongensis</i> contigs on the right. While a general macrosynteny between the two placozoan species is present (gray lines), 25% of the genes are translocated (blue lines) or inverted (orange lines) relative to the order of the respective <i>T</i>. <i>adhaerens</i> scaffold (illustrated for ta1). Often, entire gene blocks are translocated (different colors in boxed <i>H</i>. <i>hongkongensis</i> contigs). Black stretches mark genomic regions not matching any of the 10 <i>T</i>. <i>adhaerens</i> scaffolds, while white stretches mark gaps in the <i>T</i>. <i>adhaerens</i> scaffolds. (B) Pairwise protein and CDS distances for 6,554 one-to-one orthologous genes. A significant fraction of orthologs have larger protein than CDS distance, but only three of these are, in fact, positively selected (reflected by dN/dS ratios > 1, gray line). Orthologs are sorted by increasing dN/dS. Calculated distances can be found in the <i>H</i>. <i>hongkongensis</i> data repository at <a href="https://bitbucket.org/molpalmuc/hoilungia-genome/src/master/orthologs/" target="_blank">https://bitbucket.org/molpalmuc/hoilungia-genome/src/master/orthologs/</a>. CDS, coding sequence; dN/dS, nonsynonymous to synonymous nucleotide substitutions.