Geographic Patterns of Introgressive Hybridization Between Native Yellowstone Cutthroat Trout, Oncorhynchus Clarki Bouvieri, and Introduced Rainbow Trout, Oncorhynchus Mykiss PDF Download

Author: Kelly Gunnell
Publisher:
ISBN:
Category :
Languages : en
Pages : 180

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Author:
Publisher:
ISBN:
Category : Aquatic sciences
Languages : en
Pages : 666

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Author: Michael L. Arnold
Publisher: OUP Oxford
ISBN: 0191561614
Category : Science
Languages : en
Pages : 247

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Reticulate Evolution and Humans is the first book to describe the effect of genetic exchange on the origin and evolution of our own species as well as those species with which we have and continue to interact closely, both evolutionarily and culturally. After demonstrating how genetic exchange has affected H. sapiens, the book goes on to describe how the same processes have structured the evolution of organisms on which the human species depends for shelter, sustenance and companionship. It also considers the "dark-side ̈of gene transfer as it pertains to the evolution and adaptation of human disease vectors and diseases. The development of the central thesis of this book - that reticulate evolution via introgressive hybridization and lateral gene transfer has been a pervasive factor in the evolution and cultural development of H. sapiens, its ancestors, sister taxa and associated organisms - reveals the extent of these processes across the widest of taxonomic, temporal and spatial bounds. We cannot escape the conclusion that we are constantly fed, entertained, sheltered, attacked and killed by organisms that possess mosaic genomes reflective of widespread genetic exchange during evolutionary diversification.

Author: Joanna R. Freeland
Publisher: John Wiley & Sons
ISBN: 1119993083
Category : Science
Languages : en
Pages : 361

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Molecular Ecology, 2nd Edition provides an accessible introduction to the many diverse aspects of this subject. The book takes a logical and progressive approach to uniting examples from a wide range of taxonomic groups. The straightforward writing style offers in depth analysis whilst making often challenging subjects such as population genetics and phylogenetics highly comprehensible to the reader. The first part of the book introduces the essential underpinnings of molecular ecology and gives a review of genetics and discussion of the molecular markers that are most frequently used in ecological research, and a chapter devoted to the newly emerging field of ecological genomics. The second half of the book covers specific applications of molecular ecology, covering phylogeography, behavioural ecology and conservation genetics. The new edition provides a thoroughly up-to-date introduction to the field, emphasising new types of analyses and including current examples and techniques whilst also retaining the information-rich, highly readable style which set the first edition apart. Incorporates both theoretical and applied perspectives Highly accessible, user-friendly approach and presentation Includes self-assessment activities with hypothetical cases based on actual species and realistic data sets Uses case studies to place the theory in context Provides coverage of population genetics, genomics, phylogeography, behavioural ecology and conservation genetics.

Author: Carl O. Ostberg
Publisher:
ISBN:
Category : Cutthroat trout
Languages : en
Pages : 16

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Hybridization creates novel gene combinations that may generate important evolutionary novelty, but may also reduce existing adaptation by interrupting inherent biological processes, such as genotype-environment interactions. Hybridization often causes substantial change in patterns of gene expression, which, in turn, may cause phenotypic change. Rainbow trout (Oncorhynchus mykiss) and cutthroat trout (O. clarkii) produce viable hybrids in the wild, and introgressive hybridization with introduced rainbow trout is a major conservation concern for native cutthroat trout. The two species differ in body shape, which is likely an evolutionary adaptation to their native environments, and their hybrids tend to show intermediate morphology. The characterization of gene expression patterns may provide insights on the genetic basis of hybrid and parental morphologies, as well as on the ecological performance of hybrids in the wild. Here, we evaluated the expression of eight growth-related genes (MSTN-1a, MSTN-1b, MyoD1a, MyoD1b, MRF-4, IGF-1, IGF-2, and CAST-L) and the relationship of these genes with growth traits (length, weight, and condition factor) in six line crosses: both parental species, both reciprocal F1 hybrids, and both first-generation backcrosses (F1 x rainbow trout and F1 x cutthroat trout). Four of these genes were differentially expressed among rainbow, cutthroat, and their hybrids. Transcript abundance was significantly correlated with growth traits across the parent species, but not across hybrids. Our findings suggest that rainbow and cutthroat trout exhibit differences in muscle growth regulation, that transcriptional networks may be modified by hybridization, and that hybridization disrupts intrinsic relationships between gene expression and growth patterns that may be functionally important for phenotypic.

Author: Matthew R. Campbell
Publisher:
ISBN:
Category : Cutthroat trout
Languages : en
Pages : 12

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Since the mid-1920s, the Idaho Department of Fish and Game has cultured Yellowstone cutthroat trout Oncorhynchus clarki bouvieri at Henrys Lake to offset declines in natural production and for use in stocking programs throughout Idaho. Since the mid-1970s, they have also produced F1 hybrids: female Yellowstone cutthroat trout * male rainbow trout O. mykiss. The ability of fishery managers, when selecting broodstock, to visually distinguish returning cutthroat trout from F1 hybrids is, therefore, crucial to avoid accidental introduction of rainbow trout genes into the hatchery-supplemented cutthroat trout population. To evaluate this ability, fish identified by staff as putative cutthroat trout or hybrids (an array of phenotypic characters are used), were sampled during two spawning seasons. Phenotypically identified fish were genetically tested using species-specific restriction fragment length polymorphisms (RFLPs) of nuclear and mitochondrial DNA gene loci and diagnostic allozyme loci. Current levels of rainbow trout introgression in the cutthroat trout population at Henrys Lake were also investigated by analyzing samples collected from the lake and several of its tributaries. Results indicated that staff's phenotypic identifications were highly accurate in distinguishing cutthroat trout from F1 hybrids when selecting broodstock (no F1 hybrids were detected among 80 samples identified as pure). However, backcrosses of F1 hybrids were identified in random collections of adults from the lake as well as fry from Henrys Lake tributaries, indicating introgression. Present levels of rainbow trout introgression are most likely the product of past rainbow trout introductions and limited, intermittent spawning of hatchery-produced F1 hybrids with wild Yellowstone cutthroat, rather than the accidental crossing of F1 hybrids with cutthroat trout at the hatchery. Current levels of introgression are inadvertently maintained by (1) the inability of managers to phenotypically identify and exclude as broodstock individuals with low levels of rainbow trout introgression and (2) the limited, intermittent reproductive success of straying, hatchery-produced F1 hybrids.--Abstract.

Author: Carl O. Ostberg
Publisher:
ISBN:
Category : Cutthroat trout
Languages : en
Pages : 16

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Background Introgressive hybridization is an important evolutionary process that can lead to the creation of novel genome structures and thus potentially new genetic variation for selection to act upon. On the other hand, hybridization with introduced species can threaten native species, such as cutthroat trout (Oncorhynchus clarkii) following the introduction of rainbow trout (O. mykiss). Neither the evolutionary consequences nor conservation implications of rainbow trout introgression in cutthroat trout is well understood. Therefore, we generated a genetic linkage map for rainbow-Yellowstone cutthroat trout (O. clarkii bouvieri) hybrids to evaluate genome processes that may help explain how introgression affects hybrid genome evolution. Results The hybrid map closely aligned with the rainbow trout map (a cutthroat trout map does not exist), sharing all but one linkage group. This linkage group (RYHyb20) represented a fusion between an acrocentric (Omy28) and a metacentric chromosome (Omy20) in rainbow trout. Additional mapping in Yellowstone cutthroat trout indicated the two rainbow trout homologues were fused in the Yellowstone genome. Variation in the number of hybrid linkage groups (28 or 29) likely depended on a Robertsonian rearrangement polymorphism within the rainbow trout stock. Comparison between the female-merged F1 map and a female consensus rainbow trout map revealed that introgression suppressed recombination across large genomic regions in 5 hybrid linkage groups. Two of these linkage groups (RYHyb20 and RYHyb25_29) contained confirmed chromosome rearrangements between rainbow and Yellowstone cutthroat trout indicating that rearrangements may suppress recombination. The frequency of allelic and genotypic segregation distortion varied among parents and families, suggesting few incompatibilities exist between rainbow and Yellowstone cutthroat trout genomes.

Author: Steven Michael Seiler
Publisher:
ISBN:
Category : Competition (Biology)
Languages : en
Pages : 308

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Introduced species can have dramatic impacts within the native communities where they become established. In western North America, native cutthroat trout (Oncorhynchus clarkii) are experiencing drastic declines due to habitat alteration and fish introductions. Rainbow trout ( O. mykiss) are thought to be especially detrimental to cutthroat trout because they share similar life histories and can form fertile hybrid offspring, compounding interspecific competition through added pressure from hybrids. My dissertation consists of five studies developed to test ecological and environmental factors that may influence the spread of rainbow trout and cutthroat-rainbow hybrid trout within native Yellowstone cutthroat trout ( O. c. bouvieri) populations. I raised Yellowstone cutthroat trout, rainbow trout, and reciprocal first generation hybrids under common conditions and tested for differences in morphology and swimming stamina (Chapter 1), aggression and foraging ability (Chapter 2), and the strength of interspecific competition on the growth rate of Yellowstone cutthroat trout (Chapter 3). I also surveyed trout and environmental characteristics from the South Fork of the Snake River watershed to test for morphological differences between wild Yellowstone cutthroat trout, rainbow trout, and hybrids (Chapter 4) and to examine the influence of environmental characteristics on the extent of hybridization (Chapter 5). I found differences in morphology, swimming stamina, foraging behavior, and growth between Yellowstone cutthroat trout, rainbow trout, and their hybrids that place cutthroat trout at a disadvantage. The field survey found body shape differences between Yellowstone cutthroat trout, rainbow trout, and hybrids consistent with those of trout raised in the laboratory with high predictability of genetic class based on morphology alone. The degree of hybridization present at field sampling locations was related to the size of the stream and summer water temperature of the sampling location; however, level of hybridization could also be the result of distance from a location where most rainbow trout were stocked. My work provides some of the first tests of competition between cutthroat trout and rainbow trout and the influence of hybridization. This dissertation will aid in cutthroat trout conservation efforts and be of general interest to invasive species ecologists in better understanding the dynamics of invasive species success.

Author: Ryan P. Kovach
Publisher:
ISBN:
Category : Cutthroat trout
Languages : en
Pages : 11

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Human-induced hybridization between fish populations and species is a major threat to aquatic biodiversity worldwide and is particularly relevant to management of the subspecies of cutthroat trout Oncorhynchus clarkii. The upper Snake River basin in Wyoming contains one of the largest remaining populations of Yellowstone cutthroat trout O. clarkii bouvieri, a subspecies of special concern throughout its range; however, little is known about levels of hybridization between Yellowstone cutthroat trout and exotic rainbow trout O. mykiss or about the overall genetic population structure for this river basin. There is concern that the Gros Ventre River is a source of hybridization for the Snake River basin. We sampled across the upper Snake River basin to estimate levels of hybridization and population structure and to describe hybrid zone structure and spatial patterns of hybridization throughout the basin. We used this information to help resolve whether the Gros Ventre River was acting as a potential source of hybridization for the upper Snake River basin. We found that Yellowstone cutthroat trout genotypes dominated the river system, but hybridization was detected at low levels in all populations. The Gros Ventre River contained the highest levels of hybridization (population and individual) and displayed evidence of ongoing hybridization between parental genotypes. Levels of hybridization decreased as a function of distance from the Gros Ventre River, suggesting that this population is acting as a source of rainbow trout genes. These patterns were evident despite the fact that levels of genetic connectivity appeared to be higher than those observed in other cutthroat trout populations (global genetic differentiation index F ST = 0.04), and we did not find evidence for genetic isolation by distance. Management actions aimed at reducing the presence of highly hybridized cutthroat trout or rainbow trout individuals in the Gros Ventre River will help to maintain the upper Snake River basin as an important conservation area.

Author: Carl O. Ostberg
Publisher:
ISBN:
Category :
Languages : en
Pages : 157

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Introgressive hybridization creates novel gene combinations that may generate important evolutionary novelty and thus contribute to biological complexity and diversification. On the other hand, hybridization with introduced species can threaten native species, such as cutthroat trout (Oncorhynchus clarkii) following the introduction of rainbow trout (O. mykiss). While rainbow trout introgression in cutthroat trout is well documented, neither the evolutionary consequences nor conservation implications are well understood. Hybridization between rainbow and cutthroat trout occurs in the context of substantial chromosomal rearrangement, as well incompletely re-diploidized genomes. Rainbow and cutthroat trout are descended from an autopolyploid ancestor, and extensive chromosome arm rearrangements have occurred between the species following their divergence from the last common ancestor. Evidence for incomplete re-diploidization includes the occasional formation of multivalents and duplicated loci occasionally exhibit a mixture of disomic and tetrasomic inheritance. Thus, transmission genetics may be complicated by recombination between homeologs. Here, I evaluated the phenotypic and genetic consequences of introgression between rainbow trout and Yellowstone cutthroat trout (O. clarkii bouvieri) to provide insights into genome processes that may help explain how introgression affects hybrid genome evolution. The overall aim of the first part of this dissertation (Chapters 1 and 2) was to evaluate phenotypic variation and gene expression among parental species and hybrids to gain insight into the genetic basis of hybrid and parental morphologies. We constructed seven line crosses: both parental species, both reciprocal F1 hybrids, first-generation backcrosses, and F2 hybrids. In Chapter 1, we aimed to assess the role of introgression on growth (length and weight gain), morphology, and developmental instability among these seven crosses. Growth was related to the proportion of rainbow trout genome contained within crosses. Rainbow and cutthroat trout were morphologically divergent: rainbow trout were generally robust whereas cutthroat trout were typically more slender and their hybrids tended to be morphologically intermediate, although backcrosses were morphologically more similar to their backcrossing parental species. These differences in growth and body morphology may be maintained, in part, through the regulation of muscle growth-related genes. Therefore, in Chapter 2, we aimed to characterize the expression of muscle growth-related genes and to describe relationships between gene expression and growth patterns among parental species and hybrids to gain insight into the underlying genetic basis of the difference in their body shapes. Our findings suggest that rainbow and cutthroat trout exhibit differences in muscle growth regulation, that transcriptional networks may be modified by hybridization, and that hybridization disrupts intrinsic relationships between gene expression and growth patterns that may be functionally important for phenotypic adaptations. The overall aim of the second part of this dissertation (Chapters 3 and 4) was to assess the genetic consequences of introgression to determine how the genomic architecture of hybrids affects allelic inheritance, and thus their subsequent evolution. In Chapter 3, we generated a genetic linkage map for rainbow-Yellowstone cutthroat trout hybrids to evaluate genome process that may influence introgression genome evolution in hybrid populations. Our results suggest that few genomic incompatibilities exist between rainbow and cutthroat trout, allowing their to genomes introgress freely, with the exception that differences in chromosome arrangement between the species may act as barriers to introgression and enable large portions of non-recombined chromosomes to persist within admixed populations. In Chapter 4, we aimed to determine the effect of incomplete re-diploidization on transmission genetics in hybrids, compared to pure species. We used the parental gametic phase from existing genetic linkage maps to identify the homeologs that recombine, to characterize this recombination, and to verify meiotic models of residual tetrasomic inheritance in autotetraploids. Recombination between homeologs occurred frequently in hybrids and results in the non-random segregation of alleles across extended chromosomal regions as well as extensive double-reduction in hybrid parental gametes. Taken together, the results from Chapters 3 and 4 suggested that chromosome rearrangements and recombination of homeologs could influence genome evolution in admixed populations. The research presented in this dissertation indicated that the evolutionary fate of hybrid genomes is unpredictable. Some of our findings suggest that introgressions proceeds in a predictable fashion in admixed populations; rainbow and cutthroat genomes freely introgress, with the exception that chromosome rearrangements may suppress recombination across large chromosomal regions. However, homeologous recombination during meiosis in hybrids results in unpredictable segregation of chromosomes, and the segregation of these chromosomes may depend on the hybrid generation of each parent within an admixed population. Furthermore, phenotype and gene expression are quantitative traits, and expression of these traits may depend on hybrid genotypes across transcriptional networks that are controlled by genes distributed over the entire genome. Consequently, hybridization may alter transcriptional regulation of genes, resulting in unpredictable gene expression patterns, which, in turn, contribute to the high phenotypic variation in hybrids.