Author: Nathaniel P. HittPublisher:
ISBN:
Category : Cutthroat trout
Languages : en
Pages : 160
Book Description
Hybridization Between Westslope Cutthroat Trout (Oncorhynchus Clarki Lewisi) and Rainbow Trout (O. Mykiss)
Author: Nathaniel P. HittPublisher:
ISBN:
Category : Cutthroat trout
Languages : en
Pages : 160
Book Description
Management and Life History Consequences of Hybridization Between Westslope Cutthroat Trout (oncorhynchus Clarkii Lewisi) and Rainbow Trout (oncorhynchus Mykiss)
Author: Matthew CorsiPublisher:
ISBN:
Category : Cutthroat trout
Languages : en
Pages :
Book Description
The role of introductions of nonnative fishes in the decline of native fishes cannot be overstated. Westslope cutthroat trout (Oncorhynchus clarkii lewisi, WCT) are a salmonid native to the northern Rocky Mountains. These trout hybridize with rainbow trout (O. mykiss, RBT) where they are sympatric; however, in portions of the WCT range where RBT have been introduced, hybridization appears to spread rapidly and threatens continued existence of WCT. The conservation value of these hybridized populations is equivocal, and a better knowledge of the ecological, demographic, behavioral, and genetic consequences of hybridization is needed to better inform conservation strategies. I investigated three related questions: specifically, what landscape factors are associated with estimates of introgression; what are life history differences between WCT and hybrids; and what are tradeoffs in restoring migratory life history in populations threatened by hybridization? The riverscape context plays a substantial role in the distribution of hybrids, as estimates of introgression declined with increases in stream slope, elevation, and distance from a primary source of RBT, three correlated landscape variables. Spatial variation in patterns of hybridization suggests clarifying objectives for sampling and careful designs are necessary to adequately understand the status of populations. Variation in location may relate to some of the ecological differences, such as growth, among fish with different levels of introgression. In the Jocko River, hybrids with ancestry> 20% RBT demonstrated higher growth, earlier migration, increased egg size, and lower fecundity versus WCT. These lines of evidence demonstrate the importance of limiting further hybridization even in populations that already have low levels of hybridization. Given that many unaltered populations currently reside in isolated habitat fragments, I evaluated several demographic tradeoffs of restoring a migratory life history weighed against the risks of increased potential for hybridization from removing barriers or selectively passing migratory fish above the barriers using both matrix and genetic population models. Restoration of migratory life history substantially increases population viability; however, hybridization in above-barrier population increases predictably relative to hybridization status of below-barrier population, which may reduce viability if vital rates are reduced in hybrids. Hybridization creates a challenging set of management problems, but this research adds several important pieces to the puzzles to help develop and evaluate conservation strategies.
The Ecological Consequences of Hybridization Between Native Westslope Cutthroat Trout (Oncorhynchus Clarkii Lewisi) and Introduced Rainbow Trout (O. Mykiss) in South Western Alberta
Author: Michael D. RobinsonPublisher:
ISBN:
Category : Cutthroat trout
Languages : en
Pages : 152
Book Description
Behavioral, Ecological, and Fitness Consequences of Hybridization Between Native Westslope Cutthroat Trout (Oncorhynchus Clarkii Lewisi) and Nonnative Rainbow Trout (O. Mykiss)
Author: Clint Cain MuhlfeldPublisher:
ISBN:
Category : Animal ecology
Languages : en
Pages : 264
Book Description
Anthropogenic hybridization is one of the greatest threats to global biodiversity. Hybridization and introgression may lead to a loss of locally adapted gene complexes and ecological adaptations in native populations, yet these potential consequences have not been fully evaluated in nature. I investigated factors influencing the spread of hybridization between native westslope cutthroat trout (Oncorhynchus clarkii lewisi) and nonnative rainbow trout (O. mykiss) in the upper Flathead River system, Montana (USA) and British Columbia (Canada). The fundamental questions of my dissertation were: what are the behavioral, ecological, and fitness consequences of hybridization and what factors influence successful invasion of hybrids? First, I assessed the patterns of spawning between parental species and their hybrids and found that hybridization alters the spawning behavior of migratory westslope cutthroat trout, and is spreading via long distance dispersal of hybrids from downstream sources and some temporal overlap during spawning. Second, I describe for the first time how a wide range of levels of nonnative admixture affect fitness of cutthroat trout in the wild by estimating reproductive success in a recently invaded stream using parentage analysis with multilocus microsatellite markers. Small amounts of hybridization markedly reduced reproductive success, with fitness exponentially declining by ~50% with 20% nonnative genetic admixture. Finally, I evaluated the association of local-habitat features, landscape characteristics, and biotic factors with the spread of hybridization in the system, and found that hybridization increases in streams with warmer water temperatures, high land use disturbance and close proximity to the source of hybridization; however, none of these factors appeared sufficient to prevent further spread. These combined results suggest that hybrids are not only genetically different than westslope cutthroat trout but also have reduced fitness and are ecologically different, and that hybridization is likely to continue to spread if hybrid populations with high amounts of rainbow trout admixture are not reduced or eliminated. I conclude that extant aboriginal cutthroat trout are at greater conservation risk due to hybridization than previously thought and policies that protect hybridized populations need reconsideration.
Rainbow Trout (Oncorhynchus Mykiss) Invasion and the Spread of Hybridization with Native Westslope Cutthroat Trout (Oncorhynchus Clarkii Lewisi)
Author: Matthew C. BoyerPublisher:
ISBN:
Category : Cutthroat trout
Languages : en
Pages : 12
Book Description
We analyzed 13 microsatellite loci to estimate gene flow among westslope cutthroat trout, Oncorhynchus clarkii lewisi, populations and determine the invasion pattern of hybrids between native O. c. lewisi and introduced rainbow trout, Oncorhynchus mykiss, in streams of the upper Flathead River system, Montana (USA) and British Columbia (Canada). Fourteen of 31 sites lacked evidence of O. mykiss introgression, and gene flow among these nonhybridized O. c. lewisi populations was low, as indicated by significant allele frequency divergence among populations (?ST = 0.076, ?ST = 0.094, P
Naturally Occurring Hybridization and Introgression Between Westslope Cutthroat (Oncorhynchus Clarki Lewisi) and Native Rainbow Trout (Oncorhynchus Mykiss) Within Three Tributaries of the Middle Fork Salmon River, Idaho
Author: Michael Patrick PetersonPublisher:
ISBN:
Category : Rainbow trout
Languages : en
Pages : 78
Book Description
Cold Tolerance Performance of Westslope Cutthroat Trout (Oncorhynchus Clarkii Lewisi) and Rainbow Trout (Oncorhynchus Mykiss) and Its Potential Role in Influencing Interspecific Hybridization
Author: M. M. YauPublisher:
ISBN:
Category : Cutthroat trout
Languages : en
Pages : 8
Book Description
Hybridization between rainbow trout (Oncorhynchus mykiss (Walbaum, 1792)) and westslope cutthroat trout (Oncorhynchus clarkii lewisi (Girard, 1856)) occurs commonly when rainbow trout are introduced into the range of westslope cutthroat trout. Typically, hybridization is most common in warmer, lower elevation habitats, but much less common in colder, higher elevation habitats. We assessed the tolerance to cold water temperature (i.e., critical thermal minimum, CTMin) in juvenile rainbow trout and westslope cutthroat trout to test the hypothesis that westslope cutthroat trout better tolerate low water temperature, which may explain the lower prevalence of rainbow trout and interspecific hybrids in higher elevation, cold-water habitats (i.e., the ?elevation refuge hypothesis?). All fish had significantly lower CTMin values (i.e., were better able to tolerate low temperatures) when they were acclimated to 15 °C (mean CTMin = 1.37 °C) versus 18 °C (mean CTMin = 1.91 °C; p
Species Distribution of Coexisting Westslope Cutthroat Trout (Oncorhynchus Clarki Lewisi) and Rainbow Trout (Oncorhynchus Mykiss) Within the Little Naches Watershed of Eastern Washington
Author: Amy Kurant MatthewsPublisher:
ISBN:
Category : Coexistence of species
Languages : en
Pages : 184
Book Description
Diagnostic Single Nucleotide Polymorphisms for Identifying Westslope Cutthroat Trout (Oncorhynchus Clarki Lewisi), Yellowstone Cutthroat Trout (Oncorhynchus Clarkii Bouvieri) and Rainbow Trout (Oncorhynchus Mykiss)
Author: Steven T. KalinowskiPublisher:
ISBN:
Category : Animal
Languages : en
Pages : 5
Book Description
We describe 12 diagnostic single nucleotide polymorphism (SNP) assays for use in species identification among rainbow and cutthroat trout: five of these loci have alleles unique to rainbow trout (Oncorhynchus mykiss), three unique to westslope cutthroat trout (O. clarkii lewisi) and four unique to Yellowstone cutthroat trout (O. clarkii bouvieri). These diagnostic assays were identified using a total of 489 individuals from 26 populations and five fish hatchery strains.
Author: Kelly Gunnell