Marine evo-devo: New frontiers from Lophotrochozoa

The Earth has 71% of its surface covered by oceans and is home to an astonishing diversity of marine life. Unveiling the history of life requires examining the mysteries of marine organisms. Evolutionary developmental biology (evo-devo) is a rapidly growing interdisciplinary field that aims to elucidate the origin of life and histological processes that drive diversification. However, the long-standing reliance on terrestrial model species used in comparative studies overlooks the insights offered by marine life. Expanding the use of emerging marine organisms to address this knowledge gap can revolutionize evo-devo. Lophotrochozoa, one of the three major groups of Bilateria, ranks among the most species-rich clades and encompasses mollusks, annelids, flatworms, and other invertebrates. Lophotrochozoans exhibit a remarkable variety of life cycles and body plans (Figure 1), yet they have remained relatively less explored. Shifting greater focus to marine lophotrochozoans offers an unprecedented opportunity to explore the evolutionary history of life. This commentary highlights recent breakthroughs and emerging frontiers in marine evo-devo research by focusing on lophotrochozoans and highlights multiple biological perspectives.

Revolutionizing the marine evo-devo field using cutting-edge omics technologies

Advances in cutting-edge omics technologies and dramatic increases in high-quality genomes and diverse functional genomic data have revolutionized evo-devo understanding. Over the past 5 years (per NCBI, as of December 2024), the number of chromosome-level genomes of lophotrochozoans has increased 21-fold, growing from 11 to 229 species. Multi-functional omics data have expanded approximately 3-fold, from 15,338 to 42,312 datasets and covering 2,279 species. In line with this trend, the first comparative multi-omics database for animal evo-devo (EDomics, http://edomics.qnlm.ac) and the largest lophotrochozoan phylum Mollusca (MolluscDB, http://mgbase.qnlm.ac) has been established. To date, these long-overlooked genomic treasures are just beginning to be identified. Fundamental discoveries have been made regarding critical molecular mechanisms that may have driven evolutionary novelties, including high genome heterozygosity, lineage-specific gene family expansion, dynamic repertoires of transposable elements, etc. This remarkable genomic plasticity likely explains both the historical challenges in genetics and their evolutionary success. It reveals that lophotrochozoans retain unexpected similarities to bilaterians’ ancestral state. Strikingly, a near-perfect correspondence between the 19 chromosomes of a scallop and the 17 presumed bilaterian ancestral linkage groups was found, surpassing the level of correspondence observed in other bilaterians.1 Furthermore, lophotrochozoans exhibit a slow-evolving pattern with numerous ancestral features, including a deeply conserved gene repertoire and remarkable stability in genome organization.1 These unexpected findings provide unique opportunities to gain a deeper understanding of the early origins and evolutionary mechanisms that have shaped animal development.