title: Pancrustacean phylogeny: hexapods are terrestrial crustaceans and maxillopods are not monophyletic.
abstract: Recent molecular analyses indicate that crustaceans and hexapods form a clade (Pancrustacea or Tetraconata), but relationships among its constituent lineages, including monophyly of crustaceans, are controversial. Our phylogenetic analysis of three protein-coding nuclear genes from 62 arthropods and lobopods (Onychophora and Tardigrada) demonstrates that Hexapoda is most closely related to the crustaceans Branchiopoda (fairy shrimp, water fleas, etc.) and Cephalocarida + Remipedia, thereby making hexapods terrestrial crustaceans and the traditionally defined Crustacea paraphyletic. Additional findings are that Malacostraca (crabs, isopods, etc.) unites with Cirripedia (barnacles, etc.) and they, in turn, with Copepoda, making the traditional crustacean class Maxillopoda paraphyletic. Ostracoda (seed shrimp)--either all or a subgroup--is associated with Branchiura (fish lice) and likely to be basal to all other pancrustaceans. A Bayesian statistical (non-clock) estimate of divergence times suggests a Precambrian origin for Pancrustacea (600 Myr ago or more), which precedes the first unambiguous arthropod fossils by over 60 Myr.
authors.affiliation: Center for Biosystems Research, University of Maryland Biotechnology Institute, College Park, USA.
authors.forename: Jerome C
authors.initials: JC
authors.lastname: Regier
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Shultz
authors.forename: Robert E
authors.initials: RE
authors.lastname: Kambic
mesh_terms: D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D003445:Crustacea / Q000235:genetics*; D019143:Evolution, Molecular; D007313:Insecta / Q000235:genetics*; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D020648:Peptide Elongation Factor 1 / Q000235:genetics; D020652:Peptide Elongation Factor 2 / Q000235:genetics; D010802:Phylogeny; D012319:RNA Polymerase II / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D020648:Peptide Elongation Factor 1; D020652:Peptide Elongation Factor 2; D012319:RNA Polymerase II
references.citation: Nature. 2001 Sep 13;413(6852):154-7
references.pmid: 11557978
references.citation: Arthropod Struct Dev. 2003 Dec;32(4):349-83
references.pmid: 18089018
references.citation: Mol Biol Evol. 2000 Apr;17(4):639-44
references.pmid: 10742054
references.citation: Nature. 2001 Feb 1;409(6820):614-8
references.pmid: 11214319
references.citation: Mol Phylogenet Evol. 2004 Apr;31(1):178-91
references.pmid: 15019618
references.citation: Syst Biol. 2002 Oct;51(5):689-702
references.pmid: 12396584
references.citation: BMC Biol. 2004 Jan 19;2:1
references.pmid: 14731304
references.citation: J Mol Evol. 2004 Apr;58(4):413-23
references.pmid: 15114420
references.citation: Evolution. 1985 Jul;39(4):783-791
references.pmid: 28561359
references.citation: Mol Phylogenet Evol. 2001 Jul;20(1):136-48
references.pmid: 11421654
references.citation: Syst Biol. 2003 Oct;52(5):665-73
references.pmid: 14530133
references.citation: Folia Primatol (Basel). 1989;53(1-4):190-202
references.pmid: 2606395
references.citation: Nature. 1998 Apr 16;392(6677):667-8
references.pmid: 9565028
references.citation: Cladistics. 2000 Jun;16(2):155-203
references.pmid: 34902956
references.citation: Nature. 1995 Jul 13;376(6536):165-7
references.pmid: 7603566
references.citation: Proc Biol Sci. 2004 Mar 7;271(1538):537-44
references.pmid: 15129965
references.citation: Bioinformatics. 2001 Aug;17(8):754-5
references.pmid: 11524383
references.citation: Proc Natl Acad Sci U S A. 2002 Feb 5;99(3):1426-30
references.pmid: 11818548
references.citation: Nature. 2001 Sep 13;413(6852):157-61
references.pmid: 11557979
references.citation: Comput Appl Biosci. 1992 Jun;8(3):275-82
references.pmid: 1633570
references.citation: Nature. 1997 Feb 13;385(6617):627-30
references.pmid: 9024659
references.citation: Proc Natl Acad Sci U S A. 1955 Jan 15;41(1):61-6
references.pmid: 16589618