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
Suggested CitationThesis: Govindarajan, Annette F., "Life cycle evolution and systematics of Campanulariid hydrozoans", 2004-09, DOI:10.1575/1912/1857, https://hdl.handle.net/1912/1857
Showing items related by title, author, creator and subject.
Edwards, Gary W. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1992-09)The complex, many degree-of-freedom end effectors at the leading edge of technology would be unusable in the sea bottom research environment. Simpler designs are required to provide adequate reliability for subsea ...
Gunson, James R. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1995-08)The problem of estimating boundary and initial conditions for a regional open-ocean model is addressed here. With the objective of mimicking the SYNOP experiment in the Gulf Stream system, a meandering jet is modeled by ...
Johnson, Matthew L. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1993-09)The width of the main lobe of the acoustic backscatter directivity pattern of decapod shrimp (Palaemonetes vulgaris) is examined versus acoustic frequency. Using the distorted wave Born approximation (DWBA) and the ...