Evolution of Vulva Development in the Cephalobina (Nematoda)

Ventral cord and vulva development are analyzed in a large sample of nematode species of the suborder Cephalobina. We find a specific range of evolutionary variations at distinct developmental steps. (1) Unlike Caenorhabditis elegans and relatives, the vulva is formed from the four precursor cells P...

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Bibliographic Details
Published in:Developmental biology 2000-05, Vol.221 (1), p.68-86
Main Authors: Félix, Marie-Anne, De Ley, Paul, Sommer, Ralf J., Frisse, Linda, Nadler, Steven A., Thomas, W.Kelley, Vanfleteren, Jacques, Sternberg, Paul W.
Format: Article
Language:English
Subjects:
Animals
Body Patterning
cell death
Cell Lineage
Cephalobina
DNA, Ribosomal
evolution
Evolution, Molecular
Female
Genitalia, Female - embryology
Genitalia, Female - growth & development
induction
Nematoda - embryology
Nematoda - growth & development
nematode
patterning
Phylogeny
Sequence Alignment
Sequence Analysis, DNA
vulva
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Summary:Ventral cord and vulva development are analyzed in a large sample of nematode species of the suborder Cephalobina. We find a specific range of evolutionary variations at distinct developmental steps. (1) Unlike Caenorhabditis elegans and relatives, the vulva is formed from the four precursor cells P(5–8).p or, exceptionally, from P(6,7).p only. (2) The vulval competence group is restricted to these four cells or is larger. (3) The fates of more anterior and posterior Pn.p cells vary between closely related species (mostly cell death versus epidermal fate). (4) The mechanism of vulval cell fate patterning varies within a single genus, even between strains of the same species. (5) We describe the first example of a vulval cell lineage that is asymmetric between the anterior and the posterior sides of the vulva. For a selection of the investigated taxa, phylogenetic trees were constructed in order to map vulval characters and infer evolutionary polarities. We can conclude that in this group, death of the Pn.p cells probably constitutes a derived character state compared to a syncytial fate. Rhabditophanes sp. and Strongyloides ratti are placed as sister taxa, probably sharing an exclusive common ancestor in which the number of precursor cells forming the vulva was reduced from four to two.
ISSN:0012-1606
1095-564X
DOI:10.1006/dbio.2000.9665