The adult ventral nerve cord as a phylogenetic character in brachyceran Diptera

Yeates, DK, Merritt, DJ and Baker, CH (2002) The adult ventral nerve cord as a phylogenetic character in brachyceran Diptera. Organisms Diversity & Evolution, 2 2: 89-96. doi:10.1078/1439-6092-00037

Author Yeates, DK
Merritt, DJ
Baker, CH
Title The adult ventral nerve cord as a phylogenetic character in brachyceran Diptera
Journal name Organisms Diversity & Evolution   Check publisher's open access policy
ISSN 1439-6092
Publication date 2002-01-01
Year available 2002
Sub-type Article (original research)
DOI 10.1078/1439-6092-00037
Open Access Status Not yet assessed
Volume 2
Issue 2
Start page 89
End page 96
Total pages 8
Place of publication Jena, Germany
Publisher Urban & Fischer Verlag
Language eng
Subject C1
270504 Invertebrate Biology
780105 Biological sciences
Abstract Insect ganglia are often composed of fused segmental units or neuromeres. We estimated the evolution of the ventral nerve cord (VNC) in higher Diptera by comparing the patterns of neuromere fusion among 33 families of the Brachycera. Variation within families is uncommon, and VNC architecture does not appear to be influenced by body shape. The outgroup pattern, seen in lower Diptera, is fusion of neuromeres belonging to thoracic segments 1 and 2 (T1 and T2), and fusion of neuromeres derived from T3 and abdominal segment 1 (A1). In the abdomen, neuromeres A7-10 are fused into the terminal abdominal ganglion (TAG). Increased neuromere fusion is a feature of the Brachycera. No brachyceran shows less fusion than the outgroups. We established six pattern elements; (1) fusion of T1 and T2, (2) fusion of T3 and A1, (3) fusion of the T1/T2 andT3/A1 ganglia, (4) increase in the number of neuromeres comprising the TAG, (5) anteriorward fusion of abdominal neuromeres, and (6) the complete fusion of thoracic and abdominal neuromeres into a synganglion. States 1 and 2 are present in the outgroup lower Diptera, and state 3 in the Xylophagomorpha, Stratiomyomorpha, Tabanomorpha and Cyclorrhapha. State 4 is a feature of all Eremoneura. State 5 is present in Cyclorrhapha only, and state 6, fusion into a synganglion, has evolved at least 4 times in the Eremoneura. Synapomorphies are provided for the Cyclorrhapha and Muscoidea, and a grouping of three basal brachyceran infraorders Xylophagomorpha, Stratiomyomorpha and Tabanomorpha. The patterns of fusion suggest that VNC architecture has evolved irreversibly, in accordance with Dollo's law.
Keyword Evolutionary Biology
Ventral Nerve Cord
Higher-level Phylogeny
Q-Index Code C1
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Biological Sciences Publications
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Created: Wed, 15 Aug 2007, 03:26:40 EST