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Lack of support for Deuterostomia prompts reinterpretation of the first bilateria

Abstract:
The bilaterally symmetric animals (Bilateria) are considered to comprise two monophyletic groups, Protostomia (Ecdysozoa and the Lophotrochozoa) and Deuterostomia (Chordata and the Xenambulacraria). Recent molecular phylogenetic studies have not consistently supported deuterostome monophyly. Here, we compare support for Protostomia and Deuterostomia using multiple, independent phylogenomic datasets. As expected, Protostomia is always strongly supported, especially by longer and higher-quality genes. Support for Deuterostomia, however, is always equivocal and barely higher than support for paraphyletic alternatives. Conditions that cause tree reconstruction errors—inadequate models, short internal branches, faster evolving genes, and unequal branch lengths—coincide with support for monophyletic deuterostomes. Simulation experiments show that support for Deuterostomia could be explained by systematic error. The branch between bilaterian and deuterostome common ancestors is, at best, very short, supporting the idea that the bilaterian ancestor may have been deuterostome-like. Our findings have important implications for the understanding of early animal evolution.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1126/sciadv.abe2741

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More by this author
Role:
Author
ORCID:
0000-0001-8769-8779
More by this author
Role:
Author
ORCID:
0000-0001-9966-4760


Publisher:
American Association for the Advancement of Science
Journal:
Science Advances More from this journal
Volume:
7
Issue:
12
Article number:
eabe2741
Publication date:
2021-03-19
Acceptance date:
2021-02-01
DOI:
EISSN:
2375-2548


Language:
English
Keywords:
Pubs id:
1168887
Local pid:
pubs:1168887
Deposit date:
2021-03-22

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