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Acoel development supports a simple planula-like urbilaterian
Open accessAbstract
Molecular approaches to the study of development and evolution have had profound effects on our understanding of the nature of the evolutionary process. Developmental biologists became intoxicated with fanciful notions of reconstructing genetic pathways of morphogenesis while evolutionary biologists were sobered by the fallacy of reconstructing organismal relationships along increasing grades of morphological complexity. Increased taxon sampling and improvements in analytical techniques are providing a new approach and are forcing biologists to move past historical biases to allow more accurate mapping of morphological and developmental characters through evolutionary time. Here, we discuss the possible developmental and morphological features of the ‘urbilaterian’, the triploblastic animal with anterior-posterior and dorsoventral axes and predecessor of the protostome–deuterostome ancestor. We argue that this animal, with features resembling acoelomorph flatworms, was far simpler morphologically than the protostome–deuterostome ancestor despite possessing a nearly complete eubilaterian genome. We show that the deployment of some genes expected to pattern the protostome–deuterostome ancestor is not deployed in acoels in the predicted manner and thus might have been co-opted after the evolution of the urbilaterian. We also identify the developmental changes related to gastrulation that gave rise to the urbilaterian from a simpler cnidarian-like ancestor.
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“in development of the most basal cnidarian clade, anthozoans, regulatory genes are expressed in bilateral axial patterns that indicate an underlying set of bilateral regulatory states.”
From An integrated view of precambrian eumetazoan evolution (2009) · cites this paper as Hejnol and Martindale 2008
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Metadata
- Authors
- Hejnol, A., & Martindale, M. Q.
- Affiliations
- University of Hawaiʻi at Mānoa (US)
- Venue
- Philosophical Transactions of the Royal Society B: Biological Sciences
- Publisher
- The Royal Society
- Published
- 2008-01-11
- Volume
- 363
- Issue
- 1496
- Pages
- 1493-1501
- ISSN
- 0962-8436 (ISSN-L)
- 1471-2970
- PMC
- PMC2614228
- OpenAlex
- W2127207904
- Cited by
- 161
- References
- 88
- Citations by year
- 2026: 4 · 2025: 6 · 2024: 5 · 2023: 2 · 2022: 6 · 2021: 21 · 2020: 4 · 2019: 5 · 2018: 7 · 2017: 3 · 2016: 7 · 2015: 11 · 2014: 7 · 2013: 9 · 2012: 5
- FWCI
- 1.52
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Locations
- Philosophical Transactions of the Royal Society B Biological Sciences (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Funders
- National Science Foundation
- Deutsche Forschungsgemeinschaft
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Developmental Biology and Gene Regulation
- Life Sciences › Agricultural and Biological Sciences › Animal Science and Zoology › Marine Invertebrate Physiology and Ecology
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Planarian Biology and Electrostimulation
- Keywords
- acoels, gene co-option, gastrulation, morphological complexity, evolutionary developmental biology, Platyhelminthes
- MeSH terms
- Animals, Biological Evolution, Female, Male, Models, Biological, Phylogeny, Platyhelminths, Developmental Biology, Evolution, Molecular, Body Patterning, Gastrulation
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