Fig. 2: Osedax and Vestimentifera exhibit distinct genome evolutionary trends.

a–c Plots comparing genome size (a), repeat content (b) and number of genes (c) between O. frankpressi and the four Vestimentifera with sequenced genomes. Osedax frankpressi has a smaller genome, with less genes but relatively similar repeat content. d Principal component analyses of the gene content of 28 metazoan genomes show that differently from symbiotic bivalves and gastropods, the gene content of Vestimentifera and O. frankpressi differs from slow-evolving asymbiotic species (as represented by Owenia fusiformis and C. teleta). While Vestimentifera has a unique gene content, O. frankpressi is like other fast-evolving annelid lineages. e, f Bar plots of the percentage of genes in gene families (i.e., orthogroups; e) and retained ancestral metazoan gene families (f) for ten annelid lineages. Osedax frankpressi is amongst the annelids with less genes in gene families and less retained ancestral metazoan genes. g Patterns of gene family gains (in green) and loss (in red) during the evolution of Annelida under a consensus tree topology³¹ and a consensus of published molecular dates^{8, 9}. A major event of gene loss is common to all Siboglinidae. While O. frankpressi continued experiencing high rates of gene loss, a major event of gene innovation is common to all Vestimentifera. h Top five enriched gene ontology terms (Biological Process) for gene families lost (top) and expanded (bottom) in O. frankpressi. While O. frankpressi has further lost genes involved in metabolism (e.g., carbohydrate metabolism), genes involved in collagen and extracellular matrix degradation are expanded. P-values were derived from upper-tail Fisher’s exact tests.