Life cycle evolution and systematics of Campanulariid hydrozoans
Govindarajan, Annette F.
MetadataShow full item record
The purpose of this thesis is to study campanulariid life cycle evolution and systematics. The Campanulariidae is a hydrozoan family with many life cycle variations, and provide an excellent model system to study life cycle evolution. Additionally, the unique campanulariid Obelia medusae may have been "re-invented" from ancestors without medusae. Chapter 1 reviews campanulariid life cycles and taxonomy. Chapter 2 presents a phylogeny based on 18S rDNA, calmodulin, L6S rDNA and cytochrome c oxidase I (COI). Ancestral life cycles are reconstructed using parsimony. Medusa loss is common, and Obelia may derive from ancestors with typical medusae. Taxonomic results are discussed in Chapter 3. Bilardia, a nominal campanulariid, appears phylogenetic ally distant, while Bonneviella spp. (Bonneviellidae), are nested within the Campanulariidae. Campanulariid genera are not monophyletic. Orthopyxis integra and elytia gracilis may represent cryptic species, while Obelia longissima may be cosmopolitan. Chapter 4 investigates Obelia geniculata phylogeography. Japanese and North Atlantic 16S rDNA and COI sequences are calibrated against the opening of the Bering Strait. Substitution rates are faster than in anthozoans and comparable to non-cnidarian invertebrates. Comparison of Pacific and Atlantic sequences suggests cryptic species exist. Finally, hydroids in New Brunswick, Canada and Iceland may have survived the last glaciation.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2004
Showing items related by title, author, creator and subject.
Turbulent convection in an anelastic rotating sphere : a model for the circulation on the giant planets Kaspi, Yohai (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2008-06)This thesis studies the dynamics of a rotating compressible gas sphere, driven by internal convection, as a model for the dynamics on the giant planets. We develop a new general circulation model for the Jovian atmosphere, ...
Lima, Ana Lucia Cessel de (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2004-06)The most ubiquitous source of polycyclic aromatic hydrocarbons (PAHs) to the environment is incomplete combustion. This study generated a high-resolution historical record of pyrogenic PAH emissions since pre-industrial ...
Migratory patterns of American shad (Alosa sapidissima) revealed by natural geochemical tags in otoliths Walther, Benjamin D. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2007-02)Geochemical signatures in the otoliths of diadromous fishes may allow for retrospective analyses of natal origins. In an assessment of river-specific signatures in American shad (Alosa sapidissima), an anadromous clupeid ...