Mitochondrial genomics and northwestern Atlantic population genetics of marine annelids
Thesis (Ph. D.)--Joint Program in Biological Oceanography (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2005. Includes bibliographical references. The overarching goal of this thesis was to investigate marine benthic invertebrate phylogeneti...
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| Other Authors: | , , , |
| Format: | Thesis |
| Language: | English |
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Massachusetts Institute of Technology
2005
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| Online Access: | http://hdl.handle.net/1721.1/39191 http://dspace.mit.edu/handle/1721.1/39191 |
| Summary: | Thesis (Ph. D.)--Joint Program in Biological Oceanography (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), 2005. Includes bibliographical references. The overarching goal of this thesis was to investigate marine benthic invertebrate phylogenetics and population genetics, focused on the phylum Annelida. Recent expansions of molecular methods and the increasing diversity of available markers have allowed more complex and fine-scale questions to be asked at a variety of taxonomic levels. At the phylogenetic level, whole mitochondrial genome sequencing of two polychaetes (the deep-sea tubeworm Riftia pachyptila and the intertidal bamboo worm Clymenella torquata) supports the placement of leeches and oligochaetes within the polychaete radiation, in keeping with molecular evidence and morphological reinvestigations. This re-interpretation, first proposed by others, synonomizes "Annelida" and "Polychaeta", and lends further support to the inclusion of echiurids, siboglinids (previously called vestimentiferans) within annelids, and sipunculans as close allies. The complete mt-genome of C. torquata was then rapidly screened to obtain markers useful in short timescale population genetics. (cont.) Two quickly evolving mitochondrial markers were sequenced from ten populations of C. torquata from the Bay of Fundy to New Jersey to investigate previous hypotheses that the Cape Cod, MA peninsula is a barrier to gene flow in the northwest Atlantic. A barrier to gene flow was found, but displaced south of Cape Cod, between Rhode Island and Long Island, NY. Imposed upon this pattern was a gradient in genetic diversity presumably due to previous glaciation, with northern populations exhibiting greatly reduced diversity relative to southern sites. These trends in C. torquata, combined with other recent short time scale population genetic research, highlight the lack of population genetics models relevant to marine benthic invertebrates. To this end, I constructed a model ... |
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