Mitogenomics and phylogenomics reveal priapulid worms as extant models of the ancestral Ecdysozoan

Webster, Bonnie L.; Copley, Richard R.; Jenner, Ronald A.; Mackenzie‐Dodds, Jacqueline; Bourlat, Sarah J.; Rota‐Stabelli, Omar; Littlewood, D. Timothy J.; Telford, Maximilian J.

doi:10.1111/j.1525-142x.2006.00123.x

Cited by 87 publications

(69 citation statements)

References 36 publications

(44 reference statements)

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“…CYCLONEURALIA, INTROVERTA, SCALIDOPHORA AND NEMATOIDA While we do not have an equivalent of the nad5 rare genomic change to support the monophyly of the Ecdysozoa within the Protostomia, as we have seen, we do have strong evidence from phylogenomic datasets of tens to hundreds of genes for the monophyly of Arthropoda plus Nematoda, Nematomorpha and Priapulida (Philippe et al 2005;Webster et al 2006). These three worm phyla had previously been linked to two further phyla, Kinorhyncha and Loricifera in a group collectively known as the Cycloneuralia (Ahlrichs 1995).…”

Section: The Ecdysozoa Is a Monophyletic Groupmentioning

confidence: 53%

The evolution of the Ecdysozoa

Telford

Bourlat

Economou

et al. 2008

Phil. Trans. R. Soc. B

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189

118

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Ecdysozoa is a clade composed of eight phyla: the arthropods, tardigrades and onychophorans that share segmentation and appendages and the nematodes, nematomorphs, priapulids, kinorhynchs and loriciferans, which are worms with an anterior proboscis or introvert. Ecdysozoa contains the vast majority of animal species and there is a great diversity of body plans among both living and fossil members. The monophyly of the clade has been called into question by some workers based on analyses of whole genome datasets. We review the evidence that now conclusively supports the unique origin of these phyla. Relationships within Ecdysozoa are also controversial and we discuss the molecular and morphological evidence for a number of monophyletic groups within this superphylum.

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Section: The Ecdysozoa Is a Monophyletic Groupmentioning

confidence: 53%

The evolution of the Ecdysozoa

Telford

Bourlat

Economou

et al. 2008

Phil. Trans. R. Soc. B

Self Cite

189

118

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“…Equally, removal of these distant outgroups and their replacement with shorter branched taxa (e.g. Onychophora and Priapulida [27]) results in increased support for Mandibulata over Myriochelata (figure 2d and electronic supplementary material, figure S3d ). We also performed a bootstrap analysis (under CAT þ G ) excluding the fast evolving nematodes and tardigrades, which found 90 per cent support for Mandibulata.…”

Section: Results (A) Phylogenomic Analyses Support Mandibulatamentioning

confidence: 99%

A congruent solution to arthropod phylogeny: phylogenomics, microRNAs and morphology support monophyletic Mandibulata

et al. 2010

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While a unique origin of the euarthropods is well established, relationships between the four euarthropod classes-chelicerates, myriapods, crustaceans and hexapods-are less clear. Unsolved questions include the position of myriapods, the monophyletic origin of chelicerates, and the validity of the close relationship of euarthropods to tardigrades and onychophorans. Morphology predicts that myriapods, insects and crustaceans form a monophyletic group, the Mandibulata, which has been contradicted by many molecular studies that support an alternative Myriochelata hypothesis (Myriapoda plus Chelicerata). Because of the conflicting insights from published molecular datasets, evidence from nuclear-coding genes needs corroboration from independent data to define the relationships among major nodes in the euarthropod tree. Here, we address this issue by analysing two independent molecular datasets: a phylogenomic dataset of 198 protein-coding genes including new sequences for myriapods, and novel microRNA complements sampled from all major arthropod lineages. Our phylogenomic analyses strongly support Mandibulata, and show that Myriochelata is a tree-reconstruction artefact caused by saturation and long-branch attraction. The analysis of the microRNA dataset corroborates the Mandibulata, showing that the microRNAs miR-965 and miR-282 are present and expressed in all mandibulate species sampled, but not in the chelicerates. Mandibulata is further supported by the phylogenetic analysis of a comprehensive morphological dataset covering living and fossil arthropods, and including recently proposed, putative apomorphies of Myriochelata. Our phylogenomic analyses also provide strong support for the inclusion of pycnogonids in a monophyletic Chelicerata, a paraphyletic Cycloneuralia, and a common origin of Arthropoda (tardigrades, onychophorans and arthropods), suggesting that previous phylogenies grouping tardigrades and nematodes may also have been subject to tree-reconstruction artefacts.

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“…They certainly had anterior sensory and feeding organs, as well as a welldeveloped gut. Webster et al (2006) have argued that the slowly evolving priapulids provide our best anatomical and genetic guide to ancestral ecdysozoan biology. Thus, living priapulids may provide broad insights into T. pedum biology, even if the specimens of Treptichnus pedum do not offer specific clues to the producers' morphology.…”

Section: Paleobiologymentioning

confidence: 99%

Deep-Water Incised Valley Deposits at the Ediacaran-Cambrian Boundary in Southern Namibia Contain Abundant Treptichnus Pedum

Wilson

Grotzinger

Fischer

et al. 2012

PALAIOS

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Valley-filling deposits of the Nama Group, southern Namibia, record two episodes of erosional downcutting and backfill, developed close together in time near the Ediacaran-Cambrian boundary. Geochronological constraints indicate that the older valley fill began 539.4 ± 1 Ma or later; the younger of these deposits contains unusually well-preserved populations of the basal Cambrian trace fossil Treptichnus pedum. Facies analysis shows that T. pedum is closely linked to a nearshore sandstone deposit, indicating a close environmental or taphonomic connection to very shallow, mud-draped sandy seafloor swept by tidal currents. Facies restriction may limit the biostratigraphic potential of T. pedum in Namibia and elsewhere, but it also illuminates functional and ecological interpretation. The T. pedum tracemaker was a motile bilaterian animal that lived below the sediment-water interface-propelling itself forward in upward-curving projections that breached the sediment surface. The T. pedum animal, therefore, lived infaunally, perhaps to avoid predation, surfacing regularly to feed and take in oxygen. Alternatively, the T. pedum animal may have been a deposit feeder that surfaced largely for purposes of gas exchange, an interpretation that has some support in the observed association of T. pedum with mud drapes. Treptichnus pedum provides our oldest record of animals that combined anatomical and behavioral complexity. Insights from comparative biology suggest that basal Cambrian T. pedum animals already possessed the anatomical, neurological, and genetic complexity needed to enable the body plan and behavioral diversification recorded by younger Cambrian fossils.

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Mitogenomics and phylogenomics reveal priapulid worms as extant models of the ancestral Ecdysozoan

Cited by 87 publications

References 36 publications

The evolution of the Ecdysozoa

The evolution of the Ecdysozoa

A congruent solution to arthropod phylogeny: phylogenomics, microRNAs and morphology support monophyletic Mandibulata

Deep-Water Incised Valley Deposits at the Ediacaran-Cambrian Boundary in Southern Namibia Contain Abundant Treptichnus Pedum

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