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Title Taxonomic and Morphological Evaluation of an Endemic Freshwater Gastropod
URL
Publication Date
Date Accessioned
Degree MS
Discipline/Department Ecology and Evolutionary Biology
Degree Level masters
University/Publisher University of Michigan
Abstract Mollusks are the second most diverse animal phylum in terms of number of described species and nonmarine mollusks are among the most imperiled groups of invertebrate taxa. In particular, freshwater and terrestrial mollusks have the highest number of documented extinctions of any major taxonomic group. Such extinctions are not without their consequences as nonmarine mollusks provide several ecosystem functions including regulation of rates of primary production, decomposition, water clarity, and nutrient cycling. Given this and the level of fluidity found within freshwater mollusk taxonomy, the proper identification of potentially endangered species is an issue of great concern. The present study evaluates the taxonomic status of a small freshwater snail endemic to southeastern Oregon within the Owyhee River, referred to here as the Owyhee physa. Molecular, morphological, and environmental analyses were employed using specimens from both a sister species, “Physa gyrina”, and another species with similar morphology and habitat conditions as the Owyhee physa, Physa zionis. Molecular analyses also incorporated supplemental sequences from other physid species to assess the status of the Owyhee physa within the Physidae family. Genetic analyses at the cytochrome oxidase 1 and ITS-1 and ITS-2 gene regions indicate that the Owyhee physa is a phylogenetically distinct species with “Physa gyrina” as its sister species. Using theoretical morphological techniques, the shell morphology of each of the three physid species was qualitatively described. Qualitative analyses of these morphological descriptions along with the phylogenetic tree and environmental data for each species suggests that convergent evolution played an important role in influencing shell morphology within this taxonomic group. The present work has provided additional information about the current status of Physidae species richness, but additional studies must be done to both broaden and deepen our knowledge of freshwater gastropod diversity.
Subjects/Keywords Mollusks, Physa, Taxonomy, Conservation, Morphology, Evolution; Science - Conservation Genetics
Contributors Duda, Thomas F. (advisor); Burch, John B. (committee member); Dick, Christopher W. (committee member); Pappas, Janice L. (committee member)
Language en
Rights Unrestricted
Country of Publication us
Record ID handle:2027.42/98979
Repository umich
Date Indexed 2020-09-09
Grantor University of Michigan
Issued Date 2013-01-01 00:00:00
Note [thesisdegreename] Master of Science; [thesisdegreediscipline] Ecology and Evolutionary Biology; [thesisdegreegrantor] University of Michigan; [bitstreamurl] http://deepblue.lib.umich.edu/bitstream/2027.42/98979/1/Moore_Alex_Thesis.pdf;

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…freshwater snail endemic to southeastern Oregon within the Owyhee River, referred to here as the Owyhee physa. Molecular, morphological, and environmental analyses were employed using specimens from both a sister species, “Physa gyrina”, and another species…

…with similar morphology and habitat conditions as the Owyhee physa, Physa zionis. Molecular analyses also incorporated supplemental sequences from other physid species to assess the status of the Owyhee physa within the Physidae family. Genetic analyses…

…at the cytochrome oxidase 1 and ITS-1 and ITS-2 gene regions indicate that the Owyhee physa is a phylogenetically distinct species with “Physa gyrina” as its sister species. Using theoretical morphological techniques, the shell morphology of each of…

…in 1988, this physid snail (hereafter called the Owyhee physa) was rudimentarily described in a report of the Columbia Basin Mollusk Species of Special Concern (Frest and Johannes 1995). Frest and Johannes recognize that the Owyhee…

physa may be a distinct species, but did not formally describe it in their report. During later surveys, Dr. Robert Hershler of the American Museum of Natural History, David Hopper of the Idaho US Fish and Wildlife Service, and Dr. Don Sada of the…

…University of Nevada – Reno all noted the Owyhee physa and found no other similar molluscan species in the Great Basin and the Owyhee Drainage region (D. Hopper, personal communication). In a family of 6 cosmopolitan species, the Owyhee physa

…and wildlife agencies because of its highly restricted range and ongoing threats to its survival (Frest and Johannes 1995). However, because the Owyhee physa has not been formally recognized as a species and so little is known about the role…

…it plays in its environment, little progress has been made towards protecting it. In light of this, the purpose of the present study is to determine the taxonomic status of the Owyhee physa. Additionally, because the Owyhee physa requires a very…

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