Author: David M. Malakauskas
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 66

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Author: Kathleen Gallen O'Malley
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 298

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The genetic basis of adaptation is complex as many fitness-related traits are quantitative and likely influenced by multiple genes with variable effects across different selective environments. One important adaptation for anadromous Chinook salmon (Oncorhynchus tshawytscha) is the time at which individuals return to natal breeding sites within a reproductive season. Here, I tested for adaptive genetic differentiation among temporally divergent migratory runs using candidate loci. First, I isolated and characterized two copies of the circadian rhythm gene, Clock, from Chinook salmon (OtsClock1a and OtsClock1b). Phylogenetic analysis revealed that these copies likely arose subsequent to the salmonid genome-wide duplication event. Each copy contains a polyglutamine repeat motif (PolyQ), an essential binding domain of this transcription factor. However, a 1200bp non-coding segment, showing >90% sequence identity to the Salmo salar Transferrin gene, is located downstream of the OtsClock1a PolyQ, yet absent from OtsClock1b providing evidence for nonhomologous recombination. Another candidate, Ots515NWFSC, shows sequence identity to three salmonid genes central to reproductive development: Gonadotropin-releasing hormone, CYP19b-I, and Ghrelin. I employed OtsClock1b and Ots515NWFSC to test for differentiation in two unique systems: Feather River, California; and Waitaki and Poulter Rivers, New Zealand. Based on length variation in these candidate genes, Feather River fall and spring run Chinook salmon are genetically differentiated. In contrast, these seasonal runs are genetically indistinguishable based on neutral microsatellite loci. Correspondingly, temporally divergent Chinook salmon runs in the Waitaki and Poulter Rivers show greater differentiation based on variation in OtsClock1b and Ots515NWFSC than microsatellite loci. Tests for selective neutrality indicate that OtsClock1b and Ots515NWFSC are likely under selection in both systems. In addition, I found evidence for a latitudinal cline in two OtsClock1b PolyQ alleles among 42 Chinook salmon runs which is likely maintained by selection and thus may reflect an adaptation to photoperiodic parameters. Lastly, a hierarchical gene diversity analysis of OtsClock1b PolyQ variation revealed that run timing explained 43.7% of the overall genetic variance which contrast sharply with the 8.1% calculated for microsatellite loci. Evidence presented here suggests that OtsClock1b and Ots515NWFSC may influence migration timing of Chinook salmon.

Author: James B. Shaklee
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 82

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Author:
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 162

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Author: Kevin Sean Williamson
Publisher:
ISBN:
Category :
Languages : en
Pages : 260

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Author: Charles O. Junge
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 40

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Author: Elizabeth A. Campbell
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 78

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Author:
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Category :
Languages : en
Pages :

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The development of the Snake River hydroelectric system has affected fall chinook salmon smolts by shifting their migration timing to a period when downstream reservoir conditions are unfavorable for survival. Subsequent to the Snake River chinook salmon fall-run Evolutionary Significant Unit being listed as Threatened under the Endangered Species Act, recovery planning has included changes in hydrosystem operations to improve water temperature and flow conditions during the juvenile chinook salmon summer migration period. In light of the limited water supplies from the Dworshak reservoir for summer flow augmentation, and the associated uncertainties regarding benefits to migrating fall chinook salmon smolts, additional approaches for improved smolt survival need to be evaluated. This report describes research conducted by PNNL that evaluated relationships among river discharge, hyporheic zone characteristics, and egg pocket water temperature in Snake River fall chinook salmon spawning areas. The potential for improved survival would be gained by increasing the rate at which early life history events proceed (i.e., incubation and emergence), thereby allowing smolts to migrate through downstream reservoirs during early- to mid-summer when river conditions are more favorable for survival. PNNL implemented this research project throughout 160 km of the Hells Canyon Reach (HCR) of the Snake River. The hydrologic regime during the 2002?2003 sampling period exhibited one of the lowest, most stable daily discharge patterns of any of the previous 12 water years. The vertical hydraulic gradients (VHG) between the river and the riverbed suggested the potential for predominantly small magnitude vertical exchange. The VHG also showed little relationship to changes in river discharge at most sites. Despite the relatively small vertical hydraulic gradients at most sites, the results from the numerical modeling of riverbed pore water velocity and hyporheic zone temperatures suggested that there was significant vertical hydrologic exchange during all time periods. The combined results of temperature monitoring and numerical modeling indicate that only two sites were significantly affected by short-term (hourly to daily) large magnitude changes in discharge. Although the two sites exhibited acute flux reversals between river water and hyporheic water resulting from short-term large magnitude changes in discharge, these flux reversals had minimal effect on emergence timing estimates. Indeed, the emergence timing estimates at all sites was largely unaffected by the changes in river stage resulting from hydropower operations at Hells Canyon Dam. Our results indicate that the range of emergence timing estimates due to differences among the eggs from different females can be as large as or larger than the emergence timing estimates due to site differences (i.e., bed temperatures within and among sites). We conclude that during the 2002-2003 fall chinook salmon incubation period, hydropower operations of Hells Canyon Dam had an insignificant effect on fry emergence timing at the study sites. It appears that short-term (i.e., hourly to daily) manipulations of discharge from the Hells Canyon Complex during the incubation period would not substantially alter egg pocket incubation temperatures, and thus would not affect fry emergence timing at the study sites. However, the use of hydropower operational manipulations at the Hells Canyon Complex to accelerate egg incubation and fry emergence should not be ruled out on the basis of only one water year's worth of study. Further investigation of the incubation environment of Snake River fall chinook salmon is warranted based on the complexity of hyporheic zone characteristics and the variability of surface/subsurface interactions among dry, normal, and wet water years.

Author: William Frederick Forrest
Publisher:
ISBN:
Category :
Languages : en
Pages : 206

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Author: Tasha Thompson
Publisher:
ISBN: 9781658415699
Category :
Languages : en
Pages :

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Human-driven environmental changes have altered and reduced phenotypic variation across diverse taxa, but the long-term consequences and the need for conservation action are unclear. This dissertation presents an investigation of the widespread and dramatic decline of the spring-run adult migration phenotype in wild Chinook salmon (Oncorhynchus tshawytscha), caused by dam construction and other anthropogenic activities. First, the Prologue reviews the findings of Prince et al. (2017), which identified the genetic and evolutionary basis of the spring-run phenotype. Next, Chapter 1 explores the mechanism and consequences of the decline and loss of the spring-run phenotype, finding that 1) changes in spring-run phenotype frequency are explained by changes in allele frequency at a single locus, and 2) loss of the spring-run phenotype can be rapidly followed by loss of spring-run alleles (and thus the ability to recover the phenotype). In Chapter 2, a combination of single-locus and genome-wide data is used to explore the utility of a genetic marker for run-type in addressing conservation and management questions in a population of conservation concern (the Chehalis Basin, WA), serving as an example of the ways in which the findings of Chapter 1 can be applied to immediate management questions. Finally, the Epilogue briefly describes the context of this dissertation and its relationship to broader conservation issues.