2025-11-19 カリフォルニア大学バークレー校 (UCB)
Two images of sponges (top left) and two images of ctenophores (bottom left). Which of these marine organisms is at the root of the animal family tree affects how we understand the evolution of animals, including humans.Nicole King and Jacob Steenwyk/UC Berkeley
<関連情報>
- https://news.berkeley.edu/2025/11/19/did-the-first-animal-look-like-a-sponge-or-a-comb-jelly-the-debate-continues/
- https://www.science.org/doi/10.1126/science.adw9456
- https://www.science.org/doi/10.1126/science.aec6305
- https://medibio.tiisys.com/111065/
統合系統ゲノム学は海綿動物を動物系統樹の根源に位置づける Integrative phylogenomics positions sponges at the root of the animal tree
Jacob L. Steenwyk and Nicole King
Science Published:13 Nov 2025
DOI:https://doi.org/10.1126/science.adw9456
Editor’s summary
The increased availability of high-quality genomes and improved phylogenetic methods have led to researchers revisiting many taxon relationships. Steenwyk and King took on a highly contested debate: whether sponges or comb jellies (ctenophores) were the first lineage to diverge among animals (see the Perspective by Mulhair and Redmond). Using data from 100 genomes and transcriptomes enriched for sponges, ctenophores, and cnidarians, the authors used an integrative phylogenomic approach to determine which of the nearly universal single-copy genes consistently supported either lineage as a sister taxon. Most tests conducted with this set of genes supported sponges as the sister taxon, and none supported ctenophores. This work supports early trees constructed using morphology, although it is likely not the final word in this debate. —Corinne Simonti
Abstract
Determining whether sponges or ctenophores root the animal tree has important implications for understanding early animal evolution. Here, we examined support for these competing hypotheses by constructing large and highly informative data matrices containing sequences from sponges, ctenophores, cnidarians, bilaterians, and diverse animal relatives. The new data matrices and 10 published datasets were analyzed in 785 topology tests conducted using integrative phylogenomics, a method that unifies concatenation and coalescence to identify genes with a consistent phylogenetic signal. All 490 statistically significant tests supported the sponge-sister hypothesis and none supported the ctenophore-sister hypothesis; the remaining 295 tests were inconclusive. These results provide compelling evidence for the sponge-sister hypothesis and suggest that integrative phylogenomics provides a robust and powerful approach for disentangling branches in the tree of life.
系統ゲノムの不一致を吸収する 強くて一貫したシグナルを持つ遺伝子は、海綿動物が人間の最も遠い動物の親戚であることを支持する Sponging away phylogenomic incongruence Genes with strong and consistent signals favor sponges as humans’ most distant animal relatives
Peter O. Mulhair and Anthony K. Redmond
Science Published:13 Nov 2025
DOI:https://doi.org/10.1126/science.aec6305
Determining which lineage of animals is most distantly related to humans is among the most important and heated disputes in evolutionary biology. Solving this puzzle is key to revealing the biology of the ancestors of all animals, including how they transitioned from single-celled to multicellular organisms and radiated to the dazzling diversity seen today. Scientists typically decipher the evolutionary relationships between species with phylogenomics, which uses computer models of how sequences evolve to analyze large datasets of genes. On page 751 of this issue, Steenwyk and King (1) unexpectedly refresh this phylogenomic inference approach by using only genes with strong and consistent phylogenetic signal for either of two major competing hypotheses. This strategy reveals unprecedented phylogenomic support for sponges (phylum Porifera), filterfeeders lacking organized tissues, as the sister lineage to all other animals and may also have the potential to resolve other difficult phylogenetic problems.
