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Ecdysozoan phylogeny and Bayesian inference: first use of nearly complete 28S and 18S rRNA gene sequences to classify the arthropods and their kin.
Mol Phylogenet Evol. 2004 Apr; 31(1):178-91.MP

Abstract

Relationships among the ecdysozoans, or molting animals, have been difficult to resolve. Here, we use nearly complete 28S+18S ribosomal RNA gene sequences to estimate the relations of 35 ecdysozoan taxa, including newly obtained 28S sequences from 25 of these. The tree-building algorithms were likelihood-based Bayesian inference and minimum-evolution analysis of LogDet-transformed distances, and hypotheses were tested wth parametric bootstrapping. Better taxonomic resolution and recovery of established taxa were obtained here, especially with Bayesian inference, than in previous parsimony-based studies that used 18S rRNA sequences (or 18S plus small parts of 28S). In our gene trees, priapulan worms represent the basal ecdysozoans, followed by nematomorphs, or nematomorphs plus nematodes, followed by Panarthropoda. Panarthropoda was monophyletic with high support, although the relationships among its three phyla (arthropods, onychophorans, tardigrades) remain uncertain. The four groups of arthropods-hexapods (insects and related forms), crustaceans, chelicerates (spiders, scorpions, horseshoe crabs), and myriapods (centipedes, millipedes, and relatives)-formed two well-supported clades: Hexapoda in a paraphyletic crustacea (Pancrustacea), and 'Chelicerata+Myriapoda' (a clade that we name 'Paradoxopoda'). Pycnogonids (sea spiders) were either chelicerates or part of the 'chelicerate+myriapod' clade, but not basal arthropods. Certain clades derived from morphological taxonomy, such as Mandibulata, Atelocerata, Schizoramia, Maxillopoda and Cycloneuralia, are inconsistent with these rRNA data. The 28S gene contained more signal than the 18S gene, and contributed to the improved phylogenetic resolution. Our findings are similar to those obtained from mitochondrial and nuclear (e.g., elongation factor, RNA polymerase, Hox) protein-encoding genes, and should revive interest in using rRNA genes to study arthropod and ecdysozoan relationships.

Authors+Show Affiliations

School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA. jmallatt@mail.wsu.eduNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

15019618

Citation

Mallatt, Jon M., et al. "Ecdysozoan Phylogeny and Bayesian Inference: First Use of Nearly Complete 28S and 18S rRNA Gene Sequences to Classify the Arthropods and Their Kin." Molecular Phylogenetics and Evolution, vol. 31, no. 1, 2004, pp. 178-91.
Mallatt JM, Garey JR, Shultz JW. Ecdysozoan phylogeny and Bayesian inference: first use of nearly complete 28S and 18S rRNA gene sequences to classify the arthropods and their kin. Mol Phylogenet Evol. 2004;31(1):178-91.
Mallatt, J. M., Garey, J. R., & Shultz, J. W. (2004). Ecdysozoan phylogeny and Bayesian inference: first use of nearly complete 28S and 18S rRNA gene sequences to classify the arthropods and their kin. Molecular Phylogenetics and Evolution, 31(1), 178-91.
Mallatt JM, Garey JR, Shultz JW. Ecdysozoan Phylogeny and Bayesian Inference: First Use of Nearly Complete 28S and 18S rRNA Gene Sequences to Classify the Arthropods and Their Kin. Mol Phylogenet Evol. 2004;31(1):178-91. PubMed PMID: 15019618.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Ecdysozoan phylogeny and Bayesian inference: first use of nearly complete 28S and 18S rRNA gene sequences to classify the arthropods and their kin. AU - Mallatt,Jon M, AU - Garey,James R, AU - Shultz,Jeffrey W, PY - 2003/03/04/received PY - 2003/07/18/revised PY - 2004/3/17/pubmed PY - 2004/11/13/medline PY - 2004/3/17/entrez SP - 178 EP - 91 JF - Molecular phylogenetics and evolution JO - Mol. Phylogenet. Evol. VL - 31 IS - 1 N2 - Relationships among the ecdysozoans, or molting animals, have been difficult to resolve. Here, we use nearly complete 28S+18S ribosomal RNA gene sequences to estimate the relations of 35 ecdysozoan taxa, including newly obtained 28S sequences from 25 of these. The tree-building algorithms were likelihood-based Bayesian inference and minimum-evolution analysis of LogDet-transformed distances, and hypotheses were tested wth parametric bootstrapping. Better taxonomic resolution and recovery of established taxa were obtained here, especially with Bayesian inference, than in previous parsimony-based studies that used 18S rRNA sequences (or 18S plus small parts of 28S). In our gene trees, priapulan worms represent the basal ecdysozoans, followed by nematomorphs, or nematomorphs plus nematodes, followed by Panarthropoda. Panarthropoda was monophyletic with high support, although the relationships among its three phyla (arthropods, onychophorans, tardigrades) remain uncertain. The four groups of arthropods-hexapods (insects and related forms), crustaceans, chelicerates (spiders, scorpions, horseshoe crabs), and myriapods (centipedes, millipedes, and relatives)-formed two well-supported clades: Hexapoda in a paraphyletic crustacea (Pancrustacea), and 'Chelicerata+Myriapoda' (a clade that we name 'Paradoxopoda'). Pycnogonids (sea spiders) were either chelicerates or part of the 'chelicerate+myriapod' clade, but not basal arthropods. Certain clades derived from morphological taxonomy, such as Mandibulata, Atelocerata, Schizoramia, Maxillopoda and Cycloneuralia, are inconsistent with these rRNA data. The 28S gene contained more signal than the 18S gene, and contributed to the improved phylogenetic resolution. Our findings are similar to those obtained from mitochondrial and nuclear (e.g., elongation factor, RNA polymerase, Hox) protein-encoding genes, and should revive interest in using rRNA genes to study arthropod and ecdysozoan relationships. SN - 1055-7903 UR - https://www.unboundmedicine.com/medline/citation/15019618/Ecdysozoan_phylogeny_and_Bayesian_inference:_first_use_of_nearly_complete_28S_and_18S_rRNA_gene_sequences_to_classify_the_arthropods_and_their_kin_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1055790303002902 DB - PRIME DP - Unbound Medicine ER -