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Author: Steven Michael Seiler Publisher: ISBN: Category : Hybridization Languages : en Pages : 8
Book Description
?Successful? introduced species are often thought to cause declines or extinctions of native species through competitive superiority. In western North America, introduced rainbow trout, Oncorhynchus mykiss, have completely replaced many native cutthroat trout, Oncorhynchus clarkii, populations; however, few studies have identi?ed the mechanisms that may allow rainbow trout to outcompete cutthroat trout. We raised Yellowstone cutthroat trout, Oncorhynchus clarkii bouvieri, rainbow trout, and their ?rst generation hybrids in a common environment and conducted pairwise contests to test for differences in aggression, ability to defend a feeding station, and amount of food captured between these species and their hybrids.We did not detect a difference in number of aggressive acts conducted between cutthroat, rainbow and hybrid trout; however, cutthroat trout had the lowest success in occupying the feeding station and captured a lower proportion of food than rainbow and hybrid trout. Furthermore, hybrid crosses and rainbow trout had highest success at holding the feeding station and capturing food items when competing against cutthroat trout. Our study suggests that juvenile Yellowstone cutthroat trout are less successful at maintaining pro?table feeding territories and capturing food items when competing against rainbow trout and ?rst generation hybrids.
Author: Steven Michael Seiler Publisher: ISBN: Category : Hybridization Languages : en Pages : 8
Book Description
?Successful? introduced species are often thought to cause declines or extinctions of native species through competitive superiority. In western North America, introduced rainbow trout, Oncorhynchus mykiss, have completely replaced many native cutthroat trout, Oncorhynchus clarkii, populations; however, few studies have identi?ed the mechanisms that may allow rainbow trout to outcompete cutthroat trout. We raised Yellowstone cutthroat trout, Oncorhynchus clarkii bouvieri, rainbow trout, and their ?rst generation hybrids in a common environment and conducted pairwise contests to test for differences in aggression, ability to defend a feeding station, and amount of food captured between these species and their hybrids.We did not detect a difference in number of aggressive acts conducted between cutthroat, rainbow and hybrid trout; however, cutthroat trout had the lowest success in occupying the feeding station and captured a lower proportion of food than rainbow and hybrid trout. Furthermore, hybrid crosses and rainbow trout had highest success at holding the feeding station and capturing food items when competing against cutthroat trout. Our study suggests that juvenile Yellowstone cutthroat trout are less successful at maintaining pro?table feeding territories and capturing food items when competing against rainbow trout and ?rst generation hybrids.
Author: Neal K. Van Alfen Publisher: Elsevier ISBN: 0080931391 Category : Technology & Engineering Languages : en Pages : 2745
Book Description
Encyclopedia of Agriculture and Food Systems, Second Edition, Five Volume Set addresses important issues by examining topics of global agriculture and food systems that are key to understanding the challenges we face. Questions it addresses include: Will we be able to produce enough food to meet the increasing dietary needs and wants of the additional two billion people expected to inhabit our planet by 2050? Will we be able to meet the need for so much more food while simultaneously reducing adverse environmental effects of today’s agriculture practices? Will we be able to produce the additional food using less land and water than we use now? These are among the most important challenges that face our planet in the coming decades. The broad themes of food systems and people, agriculture and the environment, the science of agriculture, agricultural products, and agricultural production systems are covered in more than 200 separate chapters of this work. The book provides information that serves as the foundation for discussion of the food and environment challenges of the world. An international group of highly respected authors addresses these issues from a global perspective and provides the background, references, and linkages for further exploration of each of topics of this comprehensive work. Addresses important challenges of sustainability and efficiency from a global perspective. Takes a detailed look at the important issues affecting the agricultural and food industries today. Full colour throughout.
Author: Steven Michael Seiler Publisher: ISBN: Category : Competition (Biology) Languages : en Pages : 308
Book Description
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: Daniel P. Drinan Publisher: ISBN: Category : Languages : en Pages : 213
Book Description
Hybridization is an important and common evolutionary process that can contribute to diversification, adaptation, and speciation. When species hybridize, divergent genomes are combined through recombination and may result in phenotypic changes. Such phenotypic changes may be the result of differences in chromosomal structure or adaptive divergence between the parental species and may ultimately affect fitness. Understanding how phenotypes change following hybridization, as well as the genetic mechanisms responsible for changes is critical for understanding divergent selection, speciation, and identifying populations that may be at risk from hybridization. Here, the effect of hybridization between cutthroat (Oncorhynchus clarkii) and rainbow trout (O. mykiss) on fitness was investigated using three techniques. In the first chapter, fitness influencing traits were compared among individuals at various hybridization levels. In the second chapter, genomic changes that could affect fitness were identified in the hybrid relative to rainbow trout. And, in the third chapter, correlations between reproductive success and hybridization were investigated in a wild population, as well as the genomic and ecological mechanisms responsible for those changes. The first chapter of this dissertation aimed to identify how traits potentially involved in fitness (embryonic survival, ova size, ova energy concentration, sperm motility, burst swimming performance, juvenile survival, and juvenile growth) changed with hybridization between cutthroat and rainbow trout and whether those changes could explain previously observed reductions in reproductive success of individuals with increased rainbow trout ancestry. Using progeny from wild caught fish, differences in phenotypes based on hybridization were observed for embryonic survival, ova energy concentration, juvenile weight, and burst swimming based on ancestry. However, the correlations differed from previously observed patterns of reproductive success and likely do not explain declines in reproductive success associated with hybridization. The second chapter of this dissertation aimed to identify how hybridization affects the genome by identifying genomic regions with changes in recombination rates in the hybrid relative to rainbow trout as well as genomic areas with excess species-specific ancestry in the hybrid. Previous studies of hybridization have observed recombination suppression in genomic regions where structural differences, such as inversions or karyotype differences, exist between parental species. Such regions may retain groups of adaptive alleles. Additionally, adaptive divergence between the parental species may result in alleles that are preferentially selected in the hybrid progeny. Identification of regions with suppressed recombination or excess species-specific ancestry would provide insight into markers that may be important to fitness and that have differentially evolved in each of the parental species. In total, eight and seven chromosomes were identified to have changes in recombination rates in the hybrid female and male relative to O. mykiss. Recombination was suppressed in the hybrids on two chromosomes with known structural differences between the parental species. In addition, changes in recombination rates were observed on five chromosomes with high proportions of duplicated markers and may be due to increased homeologous chromosome pairing. Recombination patterns were similar between the sexes which suggests that hybridization affects recombination in the same way in females and males. Regions of excess species-specific ancestry covered 11 and 10% of the mapped genome in the female and male and regions of excess were evenly split between cutthroat trout and O. mykiss. Genetic drift may be responsible for much of the observed patterns of excess species-specific ancestry, but selection may also play a role. The aim of the third chapter of this dissertation was to identify the fitness consequences of hybridization, mechanisms responsible for the retention of hybridization, and genomic regions correlated with changes in reproductive success in a wild population of westslope cutthroat trout hybridized with non-native rainbow trout. Adult samples from a previous study, collected over a five year period, were sequenced at 3027 loci. Increased admixture from non-native rainbow trout had a strong, negative effect on reproductive success. A decline of 53% was observed for individuals with an increased genetic contribution of 0.20 from rainbow trout. Despite apparent strong selection against rainbow trout ancestry, hybridization appears to be maintained largely by the invasion of rainbow trout from outside populations as well as the relatively high fitness of few hybrid individuals. Ten loci correlated with reproductive success were identified in females. Seven of the ten loci were linked to chromosomes and three were positioned on chromosomes. Loci linked to reproductive success were identified on chromosomes with excess species-specific ancestry in hybrid progeny (RYHyb14 and RYHyb18) as well as chromosomes with a high proportion of duplicated markers (RYHyb02) and known Robertsonian polymorphism (RYHyb20). The research presented in this dissertation will elucidate our understanding of the phenotypic and genetic changes correlated with hybridization between rainbow and cutthroat trout as well as identify genetic and ecological mechanisms that may be responsible for those changes. In addition, results from this study provide insight into differences in adaptive divergence and markers that may be involved in the early stages of speciation in the wild. Results could be used by managers to identify populations that are at risk from hybridization.
Author: Carl O. Ostberg Publisher: ISBN: Category : Cutthroat trout Languages : en Pages : 16
Book Description
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: John Martin Fennell Publisher: ISBN: Category : Rainbow trout Languages : en Pages : 152
Book Description
Native cutthroat trout populations in western North America have faced substantial declines in part due to interactions with non-native species. One such interaction, hybridization with introduced rainbow trout, is recognized as one of the most pressing concerns facing native cutthroat trout populations. I explored how one mechanism of reproductive isolation, temporal segregation, may be limiting hybridization between Yellowstone cutthroat trout and rainbow trout in the North Fork Shoshone River drainage in northwest Wyoming. Using data on adult fish spawning migration timing paired with high resolution genomic data, we provide evidence that Yellowstone cutthroat trout spawn on average 2-4.5 weeks later in the drainage than both rainbow trout and Yellowstone cutthroat trout x rainbow trout hybrids (hybrids). Additional data collected on the size and ancestry of juvenile fish in study tributaries provides further evidence that Yellowstone cutthroat trout spawn later in the spawning season compared to rainbow trout and hybrids. I also investigated how changing water temperature and discharge in the drainage throughout the spawning season may explain differences in the timing of spawning migrations between Yellowstone cutthroat trout, rainbow trout, and hybrids. Yellowstone cutthroat trout were more likely to migrate into the spawning tributary on days after the seasonal peak in stream discharge and on days where water temperature stayed at or above 6 degrees Celsius longer. While Yellowstone cutthroat trout are entering spawning tributaries later, on average, than both rainbow trout and hybrids, disproportionately high numbers of rainbow trout and hybrids paired with extended spawning seasons leads to substantial overlap between when Yellowstone cutthroat trout, rainbow trout, and hybrids are spawning in the system. Thus, I conclude that while temporal segregation in spawn timing may play some role in the persistence of unadmixed Yellowstone cutthroat trout in the drainage, additional mechanisms of reproductive isolation likely exist between the two species.
Author: Pat Trotter Publisher: Univ of California Press ISBN: 9780520254589 Category : Nature Languages : en Pages : 572
Book Description
Cutthroat tells the full story of the genuine native trout of the American West. This new edition, thoroughly revised and updated after 20 years, synthesizes what is currently known about one of our most interesting and colorful fishes, includes much new information on its biology and ecology, asks how it has fared in the last century, and looks toward its future. In a passionate and accessibly written narrative, Patrick Trotter, fly fisher, environmental advocate, and science consultant, details the evolution, natural history, and conservation of each of the cutthroat's races and incorporates more personal reflections on the ecology and environmental history of the West's river ecosystems. The bibliography now includes what may be the most comprehensive and complete set of references available anywhere on the cutthroat trout. Written for anglers, nature lovers, environmentalists, and students, and featuring vibrant original illustrations by Joseph Tomelleri, this is an essential reference for anyone who wants to learn more about this remarkable, beautiful, and fragile western native.
Author: Steven Michael Seiler
Author: Steven Michael Seiler
Author: 
Author: Neal K. Van Alfen
Author: Steven Michael Seiler
Author: Daniel P. Drinan
Author: Carl O. Ostberg
Author: John Martin Fennell
Author: Pat Trotter
Author: Jörgen Johnsson
Author: Jason D. Baumsteiger