Putative evolutionarily conserved modules of co-expressed protein-coding genes and lncRNAs in the sponges Amphimedon queenslandica and Sycon ciliatum. (A) A conceptual model of how evolutionarily conserved networks of co-expressed homologous genes and lncRNAs can be inferred across divergent sponge lineages, despite the lack of lncRNA sequence conservation; (B) Co-expression networks based on differentially expressed protein-coding and lncRNA genes in Amphimedon [20] and Sycon [18]. Nodes indicate differentially expressed coding-genes, hubs (black) represent differentially expressed lncRNAs, and edges represent significant co-expression (both positive and negative). Amphimedon-specific genes are shown in red. Sycon-specific genes are shown in green. Conserved homologous genes shared between Amphimedon and Sycon are shown in blue. See Tables S7 and S8 for the complete edge and node lists of genes, and [20] for the developmental expression profiles of AmqTCONS_1337-9, AmqTCONS_3502, and AmqTCONS_0003141 and their co-expressed protein-coding genes.