The deep-sea, soft-bottom habitat is considered the largest ecosystem on Earth, yet little is known about the biogeography of the infauna. This dissertation examines the species' ranges of the meiofaunal taxon Harpacticoida (Crustacea: Copepoda) and the macrofaunal abundance and similarity for the continental rise off the west coast of the United States. Specifically, I examined these fauna at two depths (2700 and 3700 m) and at four latitudes (approximately 34 N, 37 N, 40 N, and 43 N). To examine the species ranges of deep-sea harpacticoids, I used morphological and DNA-sequencing methods to assign individuals to species. To do so, I had to first develop new primers for my target genes. In the process of designing primers, I sequenced the complete mitochondrial genome, which is the eighth to be sequenced, of one species of shallow-water harpacticoid and ~75% of another (Chapter 2). The two mitochondrial genomes were nearly identical to each other and were more similar to the mitochondrial genome of a Poecilostomatitoida (Crustacea: Copepoda) than to the other Harpacticoida mitochondrial genomes. Copepod mitochondrial genomes are highly rearranged, so this similarity among copepod orders supports studies that suggest mitochondrial gene arrangements could be used to reconstruct copepod phylogenies. In addition to developing new primers, I had to develop an efficient DNA isolation method (Chapter 3) for individual copepods that would allow me to recover intact exoskeletons for morphological analysis. With this method, I was able to recover intact exoskeletons suitable for morphological analysis 91.6% of the time. The DNA isolated was stable for up to 32 months, and the nuclear 18S rRNA and mitochondrial cytb primers designed and tested amplified 96.6% and 96.3% of the individuals respectively. Of the 160 deep-sea individuals with morphological, 18S, and cytb data that were used in the species' range study (Chapter 4), they were assigned to 54 species on the basis of congruency among the data. Of the 45 species that had more than one individual, 13 had 1000-km-scale ranges and another 10 had 500-km-scale ranges. These results were surprising because previous studies had suggested that morphologically identical but genetically distinct (cryptic) species were common for harpacticoids, so I expected the large (> 1000 km) ranges reported for morphological studies were over estimates. This study is the first to use morphological and molecular methods to assign deep-sea harpacticoids to species, and I found only one case of cryptic species and 18 cases of phenotypically diverse species. In Chapter 5, I report macrofaunal abundance and similarity of the southern six stations and identify environmental variables the best explain variation among my stations. I found that depth patterns in abundance were group-specific and that all groups either did not differ significantly with depth or decreased significantly with depth. The environmental variables that had parallel patterns with those groups that did decrease significantly with depth were chlorophyll a and the stable isotope 15N, which are proxies for food. Regional patterns were also group specific but no environmental variables showed parallel patters with regional differences. Aplacophoran mollusks were the largest contributor to depth and regional faunal dissimilarity, and depth, 15N, and sediment particle-size distribution best explained the variation in the multivariate cloud of faunal similarity. / A Dissertation submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the
requirements for the degree of Doctor of Philosophy. / Summer Semester, 2014. / July 15, 2014. / Includes bibliographical references. / David Thistle, Professor Directing Dissertation; Scott Steppan, University Representative; Markus Huettel, Committee Member; Joel Kostka, Committee Member; Ian MacDonald, Committee Member; Patricia Spears Terebelski, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_253611 |
| Contributors | Easton, Erin E. (authoraut), Thistle, David (professor directing dissertation), Steppan, Scott (university representative), Huettel, Markus (committee member), Kostka, Joel (committee member), MacDonald, Ian (committee member), Terebelski, Patricia Spears (committee member), Department of Earth, Ocean and Atmospheric Sciences (degree granting department), Florida State University (degree granting institution) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource, computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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