Mitochondrial DNA analysis of American shad (Alosa sapidissima) populations.
Item
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Title
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Mitochondrial DNA analysis of American shad (Alosa sapidissima) populations.
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Identifier
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AAI9304710
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identifier
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9304710
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Creator
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Nolan, Kathleen Ann.
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Contributor
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Advisers: Joseph Grossfield | Sharon Cosloy
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Date
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1992
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Genetics | Biology, Molecular | Biology, Oceanography | Agriculture, Fisheries and Aquaculture
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Abstract
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Restriction endonuclease analysis of highly purified mitochondrial DNA (mtDNA) was used to differentiate among spawning stocks of American shad (Alosa sapidissima), in nine major Western Atlantic rivers. Four and five base-cutting restriction enzymes, as well as one six base-cutting enzyme, were used to prepare both individual enzyme profiles and composite genotypes. Most of the differences observed in mtDNA types were attributed to small length polymorphisms visible on polyacrylamide gels. Significant differences among frequency distributions of mtDNA genotypes generated by single restriction enzyme digests were detected among all rivers. Two stock-specific markers were detected in moderate frequencies in two rivers: a base substitution on EcoR I agarose gels (27% in the St. Johns River in Florida) and a length variant on Dde I polyacrylamide gels (62% in the Miramichi River in New Brunswick, Canada). One genotype revealed on Dde I agarose gels decreased in frequency with latitude.;Ninety-eight composite mtDNA genotypes were detected out of 161 fish tested. Forty-six percent of the genotypes were found in only single fish. Divergence values among composite genotypes were low (0.00057-0.0042) and similar to those of other anadromous fish. The divergence between American shad and hickory shad (0.055-0.0152) was an order of magnitude less than expected on the basis of a molecular clock calibrated against the fossil record.;Phenograms and cladograms were calculated which related shared composite genotypes as unrooted as well as trees rooted using hickory shad as an outgroup. The resultant analyses do not support an hypothesis of simple south to north colonization of rivers as a result of glacial retreat. The complexities of the trees may be the result of infidelity in homing as well as stocking of rivers in the recent past. The complexities of the trees and the diversity in the rivers suggest that the mtDNA analyses conducted in this study cannot be used reliably to identify river-specific stocks of shad in an open ocean fishery for the Western Atlantic using currently available methodology.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
