Details

Autor(en) / Beteiligte

• Simion, Paul
• Philippe, Hervé
• Baurain, Denis
• Jager, Muriel
• Richter, Daniel J.
• Di Franco, Arnaud
• Roure, Béatrice
• Satoh, Nori
• Quéinnec, Éric
• Ereskovsky, Alexander
• Lapébie, Pascal
• Corre, Erwan
• Delsuc, Frédéric
• King, Nicole
• Wörheide, Gert
• Manuel, Michaël

Titel

A Large and Consistent Phylogenomic Dataset Supports Sponges as the Sister Group to All Other Animals

Ist Teil von

• Current biology, 2017-04, Vol.27 (7), p.958-967

Ort / Verlag

England: Elsevier Ltd

Erscheinungsjahr

2017

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• Resolving the early diversification of animal lineages has proven difficult, even using genome-scale datasets. Several phylogenomic studies have supported the classical scenario in which sponges (Porifera) are the sister group to all other animals (“Porifera-sister” hypothesis), consistent with a single origin of the gut, nerve cells, and muscle cells in the stem lineage of eumetazoans (bilaterians + ctenophores + cnidarians). In contrast, several other studies have recovered an alternative topology in which ctenophores are the sister group to all other animals (including sponges). The “Ctenophora-sister” hypothesis implies that eumetazoan-specific traits, such as neurons and muscle cells, either evolved once along the metazoan stem lineage and were then lost in sponges and placozoans or evolved at least twice independently in Ctenophora and in Cnidaria + Bilateria. Here, we report on our reconstruction of deep metazoan relationships using a 1,719-gene dataset with dense taxonomic sampling of non-bilaterian animals that was assembled using a semi-automated procedure, designed to reduce known error sources. Our dataset outperforms previous metazoan gene superalignments in terms of data quality and quantity. Analyses with a best-fitting site-heterogeneous evolutionary model provide strong statistical support for placing sponges as the sister-group to all other metazoans, with ctenophores emerging as the second-earliest branching animal lineage. Only those methodological settings that exacerbated long-branch attraction artifacts yielded Ctenophora-sister. These results show that methodological issues must be carefully addressed to tackle difficult phylogenetic questions and pave the road to a better understanding of how fundamental features of animal body plans have emerged. •Largest and most internally consistent metazoan-scale superalignment to date•Sponges (Porifera) are sister-group to all other multicellular animals•Previous findings of trees with “Ctenophora-sister” were due to artifacts•Analyses of multigene datasets should employ site-heterogeneous evolutionary models Simion et al. demonstrate that sponges (Porifera) are the earliest branching animal lineage, using a combination of 1,719 genes that outperforms in size and quality previous datasets used to address metazoan relationships. Previous findings of comb jellies sister to other animals were likely due to an artifact known as “long branch attraction.”