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Patterns of genetic inheritance and variation through ontogeny for hatchery and wild stocks of Chinook salmonHulett, Patrick L. 12 March 1991 (has links)
Although differences between selective pressures in hatcheries
and streams have been theorized to cause genetic divergence between
hatchery and wild salmonids, evidence of this is lacking. This study
was initiated to document the presence or absence of genetic change
in hatchery and wild stocks by characterizing genetic traits in fish
of various life history stages within a single generation.
Nine biochemical traits (enzyme loci) and 12 meristic traits
were characterized for adult fall chinook and one or more juvenile
stages of their progeny of the 1984 brood year. Study groups
consisted of hatchery-reared and naturally-reared subunits of
populations in two tributaries of the lower Columbia River: Abernathy
Creek and the Lewis River. Parents of both groups from Abernathy
Creek were primarily of hatchery origin, whereas parents of both
groups from the Lewis River were primarily of wild origin. The
experimental design thus included reciprocal comparisons of hatchery and
wild-reared groups from each of two stocks: one that has been
propagated under hatchery conditions for at least five generations
and one that has evolved in a stream environment.
Both biochemical and meristic traits varied among adult and
juvenile stages within hatchery and wild groups. Changes in some of
these traits appear to have been caused by natural selection. This
was true even for Abernathy hatchery and Lewis wild groups, which
have been in the same environment for many generations. The
direction and/or degree of change in some biochemical and meristic
traits differed between hatchery and wild groups from a given stream,
suggesting that selective pressures of the hatchery and wild
environments differed in those cases. However, it could not be
determined from these data whether the observed divergence of traits
reflects general differences in hatchery and stream environments, or
if it reflects population-specific responses to site-specific
environmental conditions. The extent to which patterns of genetic
change within a single generation might vary among year classes or
generations is likewise unknown.
Evidence of temporal changes in biochemical and meristic traits
of hatchery and wild fish within a single generation has important
implications regarding the use of those traits to characterize
stocks. Assumptions of temporal stability of biochemical or meristic
traits within or between year classes should be applied with caution.
Sampling strategies of studies involving these characters should
account for the possibility of temporal heterogeneity. Finally,
these results suggest that workers using allozymes as genetic tags
should test the assumption of selective neutrality of the particular
allozyme markers being used. / Graduation date: 1991
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Variation in mitochondrial DNA and allozymes discriminates early and late forms of chinook salmon (Oncorhynchus tshawytscha) in the Kenai and Kasilof Rivers, AlaskaAdams, Noah Swayambhu 04 February 1994 (has links)
Genetic differences between early and late forms of
Alaskan chinook salmon (Oncorhynchus tshawytscha) were
identified using two genetic approaches: mitochondrial
DNA (mtDNA) analysis and protein electrophoresis. The
study populations consisted of early- and late-run chinook
salmon in each of the Kenai and Kasilof rivers in Alaska,
and a single population from the Minam River, Oregon, that
provided a relative scale for the differences among the
Alaskan populations. Two segments of mtDNA were amplified
separately using the polymerase chain reaction (PCR) and
then digested with 14 to 16 restriction enzymes. Results
showed that the two early runs were genetically similar to
each other but different from either of the late runs.
The late runs were different from each other based on the
frequency of the common haplotypes. The Minam River stock
shared two haplotypes with the Alaskan stocks and
displayed one unique haplotype. The frequency difference
in the shared haplotypes together with the presence of a
unique haplotype allowed us to separate the Oregon
population from those in Alaska. In the protein analysis,
each of the five populations was examined at 30 allozyme
loci to determine variation within and between the runs.
Based on 14 polymorphic loci, Minam River chinook salmon
were genetically distinct from the Alaskan populations.
Within the Alaskan populations, the two early runs were
most similar to each other but different from the two late
runs; the two late runs were also genetically most similar
to each other. Based on all loci, protein electrophoresis
proved to be a useful technique to separate stocks of
chinook salmon. On a locus by locus basis, however, mtDNA
was more powerful. Both mtDNA and allozyme analysis
suggest that chinook salmon may segregate into genetically
different early and late forms within a drainage. / Graduation date: 1995
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