Xenacoelomorpha is the sister group to Nephrozoa

@article{Cannon2016XenacoelomorphaIT,
  title={Xenacoelomorpha is the sister group to Nephrozoa},
  author={Johanna Taylor Cannon and Bruno C. Vellutini and Julian Smith and Fredrik Ronquist and Ulf Jondelius and Andreas Hejnol},
  journal={Nature},
  year={2016},
  volume={530},
  pages={89-93}
}
The position of Xenacoelomorpha in the tree of life remains a major unresolved question in the study of deep animal relationships. [] Key Result Here we show robust phylogenomic support for Xenacoelomorpha as the sister taxon of Nephrozoa. Our phylogenetic analyses, based on 11 novel xenacoelomorph transcriptomes and using different models of evolution under maximum likelihood and Bayesian inference analyses, strongly corroborate this result.

Molecular approaches for studying the evolution of the Xenacoelomorpha

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Xenacoelomorpha flatworms are basal Deuterostome

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Xenacoelomorpha, a Key Group to Understand Bilaterian Evolution: Morphological and Molecular Perspectives

What has been learned over the last decades on the morphology, genomics and phylogenetic relationships of the Xenacoelomorpha is revisited.

Computational analysis of gene content in Xenacoelomorpha

The phylogenetic analysis tentatively supports the placement of Xenacoelomorpha as a sister group of Ambulacraria, and the analysis of ancestral gene family content is suggestive for the phylogenetic position of the XenacoELOMorpha.

Xenacoelomorph-Specific Hox Peptides: Insights into the Phylogeny of Acoels, Nemertodermatids, and Xenoturbellids

Results from the decoded genome of the acoel Praesagittifera naikaiensis and reported xenacoelomorph Hox genes revealed that acoels share a peptide NLK(S/T)MSQ(V/I)D, which starts immediately after the homeodomain sequence of the central Hox4/5/6.

Hidden diversity of Acoelomorpha revealed through metabarcoding

Analysis of 18S rDNA metabarcoding data from three marine projects covering benthic and pelagic habitats worldwide shows that acoels have a greater richness in planktonic environments than previously described, and identifies a putative novel clade in the deep benthos that branches as sister group to the rest of Acoela, thus representing the earliest-branching acoel clade.

Phylogeny: A home for Xenoturbella

Four new deep-sea species of Xenoturbella are added from the eastern Pacific Ocean to the two already known from the Atlantic, and phylogenetic analysis aligns them at the base of the Protostomia or even as basal bilaterians.

Development of Xenoturbellida.

  • H. Nakano
  • Biology
    Results and problems in cell differentiation
  • 2019
Comparison with the other marine invertebrate larvae suggests that the morphologically simple swimming larvae described in Xenoturbella represent an ancestral larval type of all metazoans and bilaterians.

The slow evolving genome of the xenacoelomorph worm Xenoturbella bocki

The data do not provide evidence supporting the idea that Xenacoelomorpha are a primitively simple outgroup to other bilaterians and gene presence/absence data support a relationship with Ambulacraria, but it is concluded that X. bocki has a complex genome typical of bilateralians, in contrast to the apparent simplicity of its body plan.
...

References

SHOWING 1-10 OF 47 REFERENCES

Acoelomorph flatworms are deuterostomes related to Xenoturbella

This phylogeny makes sense of the shared characteristics of Xenoturbellida and Acoelomorpha, and implies the loss of various deuterostome characters in the Xenobiology including coelomic cavities, through gut and gill slits.

The Nemertodermatida are basal bilaterians and not members of the Platyhelminthes

The results imply that the last common ancestor of bilaterian metazoans was a small, benthic, direct developer without segments, coelomic cavities, nephrida or a true brain.

Deuterostome phylogeny reveals monophyletic chordates and the new phylum Xenoturbellida

To study the relationships among all deuterostome groups, an alignment of more than 35,000 homologous amino acids is assembled, including new data from a hemichordate, starfish and Xenoturbella and it is concluded that chordates are monophyletic.

The mitochondrial genome structure of Xenoturbella bocki (phylum Xenoturbellida) is ancestral within the deuterostomes

The mitochondrial genome of Xenoturbella bocki has a very conserved gene arrangement in the deuterostome group, strikingly similar to that of the hemichordates and the chordates, and thus to the ancestral deuterstome gene order.

Assessing the root of bilaterian animals with scalable phylogenomic methods

New sequence data and methods strongly uphold previous suggestions that Acoelomorpha is sister clade to all other bilaterian animals, find diminishing evidence for the placement of the enigmatic Xenoturbella within Deuterostomia, and place Cycliophora with Entoprocta and EctoproCTa.

The phylogenetic position of Acoela as revealed by the complete mitochondrial genome of Symsagittifera roscoffensis

The phylogenetic analysis supports the view that acoels and nemertodermatids are the earliest divergent extant lineage of Bilateria and remain a valid source for seeking primitive characters present in the last common ancestor of Bilatersia.

On the phylogenetic position of Myzostomida: can 77 genes get it wrong?

It is concluded that reliance of a set of markers belonging to a single class of macromolecular complexes might bias the analysis, and that concatenation of all available data might introduce conflicting signal into phylogenetic analyses.

Error, signal, and the placement of Ctenophora sister to all other animals

Investigating possible causes of systematic error by expanding taxon sampling with eight novel transcriptomes, strictly enforcing orthology inference criteria, and progressively examining potential causes of systemic error while using both maximum-likelihood with robust data partitioning and Bayesian inference with a site-heterogeneous model finds a single, statistically robust placement of ctenophores as the authors' most distant animal relatives.

New deep-sea species of Xenoturbella and the position of Xenacoelomorpha

Four new Xenoturbella species from deep waters of the eastern Pacific Ocean are described and Phylogenomic analyses of transcriptomic sequences support placement of Xenacoelomorpha as sister to Nephrozoa or Protostomia.