Complex colony‐level organization of the deep‐sea siphonophore Bargmannia elongata (Cnidaria, Hydrozoa) is directionally asymmetric and arises by the subdivision of pro‐buds

@article{Dunn2005ComplexCO,
  title={Complex colony‐level organization of the deep‐sea siphonophore Bargmannia elongata (Cnidaria, Hydrozoa) is directionally asymmetric and arises by the subdivision of pro‐buds},
  author={Casey W. Dunn},
  journal={Developmental Dynamics},
  year={2005},
  volume={234}
}
  • C. Dunn
  • Published 1 December 2005
  • Biology, Environmental Science
  • Developmental Dynamics
Siphonophores are free-swimming colonial hydrozoans (Cnidaria) composed of asexually produced multicellular zooids. [] Key Result Each bud gives rise to a precise, directionally asymmetric sequence of zooids through a stereotypical series of subdivisions, rather than to a single zooid as in most other hydrozoans. This initial description of development in a deep-sea siphonophore provides an example of how precise colony-level organization can arise, and illustrates that the morphological complexity of…
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The evolution of colony-level development in the Siphonophora (Cnidaria:Hydrozoa)

It is shown that gonodendra and gastrozooids of the examined cystonects arise as independent buds directly on the stem, whereas probud subdivision is a synapomorphy of the Codonophora, and symmetry is labile in siphonophores, with multiple gains and/or losses of directional asymmetry in the group.

Molecular phylogenetics of the siphonophora (Cnidaria), with implications for the evolution of functional specialization.

Maximum likelihood and Bayesian analyses of morphological data suggest that the transition rate for decreased functional specialization is greater than the Transition rate for increased functional specialization for three out of the four investigated categories of polyps and medusae.

Re-evaluation of characters in Apolemiidae (Siphonophora), with description of two new species from Monterey Bay, California.

The observations presented here greatly clarify the interpretation of diagnostic characters within Apolemiidae, bear on the status of the three previously described species, provide critical detail for understanding the diversity of colony-level organization in siphonophores, and establish a foundation for the description of additional apolemiid species.

Stem cells in a colonial animal with localized growth zones

This work characterize the distribution of interstitial stem cells (i-cells) in the siphonophore Nanomia bijuga and finds that i-cells are present at the tips of the growth zones, at well-defined sites where new zooids will arise, and in the youngest zooid buds.

Cnidarian phylogenetic relationships as revealed by mitogenomics

These analyses suggest that the shared morphological characters in these groups are plesiomorphies, originated in the branch leading to Medusozoa, and the hypothesis that Staurozoa is the sister group to all the other medusozoans is rejected.

Improved phylogenetic resolution within Siphonophora (Cnidaria) with implications for trait evolution

This new phylogeny is used to reconstruct several traits that are central to siphonophore biology, including sexual system, gain and loss of zooid types, life history traits, and habitat, and find strong support for new clades within Codonophora that were previously unresolved.

Genetic identity of two physonect siphonophores from Southern Ocean waters – the enigmatic taxon Mica micula and Pyrostephos vanhoeffeni

In the present study 34 nectophores of P. vanhoeffeni and four colonies of M. micula collected from three areas in the Southern Ocean were analysed for the 16S rRNA gene, and five haplotypes were identified, which formed two clearly distinct lineages.

Evolution of Gene Expression across Species and Specialized Zooids in Siphonophora

Gen expression patterns tended to be largely consistent in zooids with the same function across species, but also some large lineage-specific shifts in gene expression, which shows that patterns of gene expression have the potential to define zooids in colonial organisms.

Stem cells in Nanomia bijuga (Siphonophora), a colonial animal with localized growth zones

The first evidence for i-cells in a siphonophore is provided, and maintenance of i-cell populations at the sites of growth zones are suggested and may explain the reduced developmental plasticity in older parts of the colony.

Modularity is the mother of invention: a review of polymorphism in bryozoans

A comprehensive description of the diversity, morphology and function of these polymorphs and the significance of modularity to the evolutionary success of the Bryozoa phylum, which has >21000 described fossil and living species.

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Maximum likelihood and Bayesian analyses of morphological data suggest that the transition rate for decreased functional specialization is greater than the Transition rate for increased functional specialization for three out of the four investigated categories of polyps and medusae.

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