Spatial and Temporal Patterns of Homeward Migration and Population Structure in Sockeye Salmon (Oncorhynchus Nerka) in the Wood River System, Bristol Bay, Alaska PDF Download
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Author: Katy K. Doctor
Publisher:
ISBN:
Category : Sockeye salmon
Languages : en
Pages : 214
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Author: Katy K. Doctor
Publisher:
ISBN:
Category : Sockeye salmon
Languages : en
Pages : 214
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Author: Molly T. McGlauflin
Publisher:
ISBN:
Category : Fish populations
Languages : en
Pages : 100
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Author: Samuel Alexander May
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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The life histories of migratory species such as salmonids, sea turtles, and birds often involve return migrations between feeding and natal habitats. These natal homing behaviors are known to produce structured metapopulations, where geographic and demographic barriers result in non-random mating among many locally adapted subpopulations. The resulting spatial and temporal diversity across heterogeneous landscapes can buffer metapopulations against disruptive events that influence any one subunit. Dispersal and gene flow within and between subpopulations can reduce fitness losses due to inbreeding depression, influence rates of adaptation, and facilitate colonization or recolonization of newly available habitat. However, an understudied aspect of metapopulation biology is the influence of biotic and abiotic factors that lead to genetic structure within and between subpopulations, and the effects of this structure on fitness. Therefore, the overall goal of this thesis was to investigate how environmental, behavioral, and life-history variation might influence dispersal, population structure, and fitness within and between subpopulations. To accomplish this goal, dispersal within and between two proximate stream-spawning populations of Sockeye salmon (Oncorhynchus nerka): A and C Creeks on the Wood River System, Bristol Bay, AK was studied over two complete generations of returning adults. First, a panel of 172 SNP loci was developed (genotyping-in-thousands by sequencing; Chapter One) and used to reconstruct a pedigree from fish returning over a 14-year period, and to identify dispersers between the two populations. Second, we investigated the drivers and fitness consequences of dispersal between A and C Creeks and found that return timing to spawning grounds and within-season variation in predation and population density influenced dispersal between the two populations (Chapter Two). Fitness consequences of dispersal depended on the direction dispersers moved; moving from A to C increased absolute fitness of dispersers (compared to individuals in their natal population) but decreased their relative fitness (compared to individuals in their new spawning population), while moving from C to A decreased absolute fitness but increased relative fitness. From these results, we concluded that dispersal was an active process in response to environmental cues and that gene flow was affected by habitat differences and within-season variation in ecological processes. Third, we aimed to examine the extent, drivers, and fitness consequences of population structure within the two streams. To achieve this aim, we quantified the scale of structure, the effect of natal homing on structure, and the fitness outcomes of homing to, and dispersing from natal sites (Chapter Three). Both spatial and temporal genetic structure was evident within both streams, and this structure was partly explained by adults returning to the same place and at the same time as they were fertilized as eggs. In addition, phenotypes of body size and return timing were spatially segregated within the creeks. In one of the two creeks, adults returning to spawn near natal sites had greater fitness. Taken together, we concluded that these findings provided empirical evidence for how natal homing and heterogeneous habitat may lead to assortative mating systems and possible microgeographic adaptation on very small spatial and temporal scales. In other words, natal homing and dispersal within populations may result in genetic or phenotypic neighborhoods and affect fitness. Finally, we discuss the utility of these findings for predicting responses of natural populations to future environmental and anthropogenic changes such as harvest, climate change, and supportive breeding.
Author: Richard R. Straty
Publisher:
ISBN:
Category : Sockeye salmon
Languages : en
Pages : 486
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The individual stocks of sockeye salmon that make up the annual spawning migration to the Bristol Bay region of Western Alaska are produced in the lakes and streams of ten major river systems, which discharge into the bay over a shoreline distance of 120 miles. The hypothesis adopted in this study was that the bay distribution of the waters from these river systems and controlling factors such as tide, wind and bottom topography determine the distribution of the individual stocks of sockeye salmon in Bristol Bay. This hypothesis was based on the premise that mature sockeye salmon return to their river system of origin to spawn and in doing so utilize recognizable characteristics of their home-river waters to guide them to its source. Hydrographic studies were carried out in upper Bristol Bay to determine the seaward course and distribution of the waters of major sockeye salmon-producing river systems draining into Bristol Bay. These studies included determination of the vertical and horizontal salinity distribution in the upper bay, tracking and plotting the distribution and course of individual river waters, which had been tagged with Rhodamine B dye, during flood and ebb tide and plotting the seaward course of plastic drift cards released at various strategic locations in upper Bristol Bay. From the results of these studies the course and distribution of the waters of each major sockeye salmon-producing river system was described for upper Bristol Bay. The distribution and migration routes of the individual stocks of Bristol Bay sockeye salmon were determined from analysis of the results of exploratory fishing operations carried out by research vessels of the United States and offshore and inshore adult sockeye salmon tagging studies conducted by the United States and Japan. The results of this analysis showed that the main migration route of all stocks of Bristol Bay sockeye is in the offshore waters of the southern half of the entrance to the bay and in the bay itself. All stocks remain in the offshore waters until within 20 to 50 miles of their home-river systems. They were, however, already beginning, to segregate according to, river of origin in the offshore waters when still as much as 150 miles from the mouths of their home-river systems. From this point to the head of Bristol Bay there was a progressive segregation of sockeye salmon stocks according to their river of origin. From these studies the general distribution and migration route of all major stocks of Bristol Bay sockeye salmon was described and illustrated on a chart of the area. Comparison of the distribution of the major river-system waters with that of their respective sockeye salmon stocks showed that the distribution of river water in outer Bristol Bay did not conform to the distribution of sockeye salmon whereas in the upper bay the individual sockeye stocks assumed a distribution which was very similar to that of their river-system waters. The conclusions reached were that the migration route, distribution and initial segregation of sockeye- stocks in the clear offshore waters of Bristol Bay are not influenced by the distribution of river water, but once in the turbid upper bay these features must somehow be related to the distribution of home-river waters and the recognizable properties they contain.
Author: Melinda L. Rowse
Publisher:
ISBN:
Category : Fishes
Languages : en
Pages : 190
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Author: Ian Jeremy Stewart
Publisher:
ISBN:
Category : Fish populations
Languages : en
Pages : 116
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Author: Marcia Marie Bender
Publisher:
ISBN:
Category : Fish populations
Languages : en
Pages : 130
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Author: Richard Robert Straty
Publisher:
ISBN:
Category :
Languages : en
Pages : 262
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Author: Patrick D. Barry
Publisher:
ISBN:
Category : Pacific salmon
Languages : en
Pages : 312
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Pacific salmon (Oncorhynchus spp.) have great ecological, economic, and cultural importance. Accordingly, understanding the genetic diversity of Pacific salmon populations is critical for their effective management and conservation. Spatial and temporal homing fidelity, a central life-history characteristic of Pacific salmon, generates genetic structure through reproductive isolation. Within and among populations, heterogeneity in the freshwater environment should lead to selection for traits that maximize fitness resulting in local adaptation. This adaptation increases productivity of individual populations while diversity among populations can promote long-term stability. Additionally, the demographic properties (age structure, generation length, size) of a population will affect genetic structure by regulating its response to the evolutionary forces of selection, migration, and genetic drift. The scale and extent to which reproductive isolation can produce genetic structure is incompletely understood. In this dissertation, I investigated spatial and temporal trends in population genetic structure and estimated the effective population size (Ne) of Sockeye Salmon from Auke Lake in Southeast Alaska from contemporary genetic samples (2008, 2009, 2011) and historic demographic data (1980–2017). A simulation library in the R statistical environment was developed to assess the accuracy of parentage and sibship inference from genetic markers. This library proved useful in evaluating the sibship method for estimating Ne from genetic data and evaluating genetic markers for a large-scale parentage project. I detected substantial genetic differentiation between Auke Lake and other Southeast Alaska populations (average FST = 0.1137) and an isolation-by-time pattern within the Auke Lake population. A genetically distinct cluster was identified in the late portion of the 2008 return. This group may represent a spatially segregated spawning aggregation previously described in tagging studies; however, because fish were sampled as they passed through the weir, spatial structure within Auke Lake could not be evaluated. Genetic tests for demographic change within the population indicated that the Auke Lake Sockeye Salmon population underwent a historical bottleneck event but has since increased in size. Demographic estimates of Ne from a long-term dataset from the Auke Creek weir revealed that the effective population size was low in the early 1980s and has since increased. Over the six generations evaluated, the major demographic factors that determined Ne were variance in family size, variable contribution to the next generation by brood years within a generation, and fluctuations in population size. Contemporary estimates of Ne from genetic methods were smaller than those from demographic methods and indicated that Ne may be roughly the size of an individual return year. Genetic estimates of the ratio of the effective population size to the census size (Ne/Nc = 0.21) were consistent with values previously reported for other salmonids. Collectively, these chapters contribute to an improved understanding of Sockeye Salmon population genetics and provide a useful tool to assess the power of genetic markers for parentage and sibship inference.
Author: Douglas Paul Peterson
Publisher:
ISBN:
Category : Benthic animals
Languages : en
Pages : 114
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