• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 5
  • 1
  • 1
  • Tagged with
  • 16
  • 8
  • 5
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Intra-specific variation in Rhinichtys c. cataractae (Valenciennes) and Rhinichthys atratulus meleagris (Agassiz) and anatomical and ecological studies of Rhinichthys c. cataractae

Becker, George C. January 1962 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 247-250).
2

Population Fragmentation and Genetic Diversity of Chrosomus sp. cf. saylori (Clinch Dace)

Bourquin, Rebecca M. 06 February 2020 (has links)
Clinch Dace (Chrosomus sp. cf. saylori) is a newly recognized species of minnow with a restricted distribution in southwestern Virginia. Field sampling and genetic analysis support the hypothesis that Clinch Dace populations are small and fragmented. Analysis of neutral genetic markers shows that most Clinch Dace populations have undergone past bottleneck events and are being operated upon by random genetic drift. Bayesian cluster analysis showed that three out of the seven populations found in 2017 are distinct, while the other four show signs of more recent admixture. However, Fst values among streams were high and analysis of molecular variance indicated differentiation among populations in all streams. These findings support the view that these populations are genetically isolated. Effective populations sizes were low at most sites, enhancing the likelihood of loss of alleles to genetic drift. Low M-ratios, non-zero Fis values, and high degrees of relatedness among individuals indicate that some inbreeding is taking place. Habitat analysis did not identify variables affecting distribution or abundance of Clinch Dace populations. As the collection sites were targeted near known Clinch Dace occupied sites, it is likely that habitat variables known to impact Clinch Dace, such as conductivity, were within the species' range of tolerance. Results showed that Clinch Dace seem particularly resilient to sedimentation, corroborating earlier work showing a negative relationship between Clinch Dace abundance to sediment size. That is, small sediment size does not seem to have a negative impact on Clinch Dace abundance. Of all sites where Clinch Dace were found, only one culvert at one site was clearly perched and may present a barrier to upstream migration, a possibility which is supported by the genetic differentiation found among collections above and below that culvert. While this study demonstrates that selectively neutral genetic differentiation has taken place among Clinch Dace populations, it does address any local adaptation that may be taking place which would render translocations a risk for outbreeding depression. The findings of this study can inform conservation management in identifying possible sources of individuals for translocations among populations or for augmentation following captive breeding. / Master of Science / The Clinch Dace is a small, threatened minnow in the Clinch River basin that was unknown until 1999. Since then, research has addressed the biology, life history, and distribution of this fish. This study used data from selectively neutral genetic markers to analyze the population structure and degree of differentiation of Clinch Dace populations. My study sites were targeted at road crossings near known Clinch Dace populations to assess the effect of habitat fragmentation on Clinch Dace populations and to maximize the likelihood that I would collect enough genetic material for analysis. Genetic analyses showed that while there is some admixture among certain populations of Clinch Dace, there is differentiation at neutral genetic markers. This differentiation does not necessarily indicate adaptive variation among populations which could result in outbreeding depression should populations be mixed through translocations, but it is reason to proceed with caution. Road crossings were generally not found to be a cause of further population fragmentation in Clinch Dace, as demonstrated by genetic analysis and statistical analysis. Almost all of the occupied road crossing sites in this study were either embedded, free-flowing culverts that were not perched or small bridges, and these were not deemed to be obvious barriers to fish movement. The only exception was Hart Creek 2, where the culvert is slightly perched and Fst is high between populations in the upstream and downstream reaches. The results of this study will help to inform managers as to what conservation actions can be taken to improve population viability. One potential management action from this study could be the retrofitting of culverts that have become perched and are acting as barriers to Clinch Dace movement. Another potential conservation strategy is to translocate individuals from large population to small populations. The study determined: 1) which translocations might be acceptable based on the degree of genetic differentiation among populations, and 2) identified potential donor and receiving streams for translocations.
3

Life History and Distribution of the Tennessee Dace (<em>Phoxinus tennesseensis</em>) in Northeast Tennessee.

Hamed, Michael Kevin 01 December 2001 (has links) (PDF)
Life history of Phoxinus tennesseensis (Tennessee dace), a species deemed "in need of management" in Tennessee and endangered in Virginia, was investigated from August 1999 to May 2001 on 2 populations in Trinkle Creek and Timbertree Branch, Sullivan County, Tennessee. Samples were taken monthly to provide information on growth, reproductive biology, preferred habitat, and demography. Observations were made during the breeding season to determine spawning strategy. Breeding season lasted from April to June. Spawning occurred over the nest of Semotilus atromaculatus (creek chub) and Campostoma anomalum (central stoneroller). With 1 to 10 females, 20 to 45 male dace gathered over the nest. Phoxinus tennesseensis populations have 4 age classes. The normal life span of the dace was about 2 years with 1st year fish constituting a majority of the total population. Historic populations and potentially new populations were sampled to determine the current distribution in Northeast Tennessee.
4

Microhabitat Use by the Redside Dace (Clinostomus Elongatus) in Ohio

Zimmerman, Brian J. 20 November 2009 (has links)
No description available.
5

MICROSATELLITE ANALYSIS OF POPULATION STRUCTURE IN THE SANTA ANA SPECKLED DACE (RHINICTHYS OSCULUS)

Nerkowski, Stacey A 01 June 2015 (has links)
Rhinichthys osculus, the Speckled Dace, is one of the most ubiquitous fish in western North America. Within the Southern California region, the local taxon is known as the Santa Ana Speckled Dace. The purpose of this study was to characterize and identify polymorphic microsatellite markers for R. osculus in which twenty-three were identified through Illumina pair-end sequencing. Seven of these loci were then used to examine the patterns of genetic variation and population structure that occurred within and among the watersheds in the Southern California. The study also examined the regional relationships among Southern California, Central California and Owen’s River Valley. Analysis of the microsatellite data revealed highly significant moderate levels of population structure exist within the Southern California region (RST=0.160, p=0.001). This structure is best explained by watershed as well as isolation by distance (R2=.2286, p=0.010). Highly significant geographic structure also exists among the geographic regions of Southern California, Central Coast, and Owen’s River Valley regions (RST= 0.600, p-value=0.001) that are congruent with the regional differentiation elucidated by mtDNA sequence data. In both cases, the degree of population differentiation was correlated with isolation by distance. Utilizing this information we were able gain a better understanding of the evolutionary relationships among the Southern California populations of Santa Ana Speckled Dace. Within the Santa Ana Speckled Dace populations we examined four models to explain the geographic structure: watershed, mountain range, tributary, and isolation by distance. While all were significant, the tributary model exhibited the higher level of population structure (RST= 0.160, p-value=0.001) and a significant correlation was exhibited between geographic distance and population structure, suggesting isolation by distance may be playing a role. The results of the microsatellite analysis are congruent with an earlier broad scale analysis of mtDNA sequence data that suggests the Central California and the Owens Valley populations diverged from each other prior to the divergence of the Santa Ana Speckled Dace populations from the Colorado Basin populations, and that the Central Coast populations were not established as a result of a migration event from the Southern California populations, as was previously hypothesized. Primarily due to human activity, Santa Ana Speckled Dace habitat has become highly fragmented resulting in some populations becoming extirpated. We hope this study will guide the strategies for the conservation of the remaining populations of Santa Ana Speckled Dace and watershed management in Southern California.
6

MOLECULAR EVOLUTION AND PHYLOGEOGRAPHY OF MITOCHONDRIAL DNA CYTOCHROME B GENE IN SOUTHERN CALIFORNIA SANTA ANA SPECKLED DACE (Rhinichthys osculus)

VanMeter, Pia Marie 01 June 2017 (has links)
In this study, I sequenced the mitochondrial cytochrome b gene to elucidate the extent and pattern of genetic variations among and within populations of Rhinichthys osculus (Santa Ana Speckled Dace) found in the different watersheds in Southern California, Central California Coast and Eastern California Desert. I described and analyzed the structural characteristics and pattern of base sequence substitutions in the cytochrome b gene to understand the molecular evolution of the gene. The Phylogenetic analyses showed that the Southern California Santa Ana Speckled dace is a distinct population from the Central California Coast dace population and Eastern California Desert dace population, and is more closely related to the Colorado River speckled dace population. There is a high degree of genetic variation among all populations including a significant genetic structure associated with watersheds, mountain ranges, and geographic grouping based on locations. The SWISS-Model automated protein structure homology elucidated the conserved and invariant residues within the cytochrome b gene where the amino acid substitutions are located in the trans-membrane of the protein sequence. The implication for conservation and management of the Southern California Santa Ana Speckled dace is high because of habitat lost for this distinct dace population. The data from this study will contribute to preserving the genetic variability of the Santa Ana Speckled Dace as a separate taxa and species, as well as to help maintain intact the population in the different Southern California creeks.
7

The Choreography from the Perspective of Political Environment ¡VBased on Lin Huai-Ming's Works in Cloud Gate Dance Company

Lo, Yen-fen 04 February 2007 (has links)
Politics, economics and social conditions often have great influences on the development of culture and Art. Moreover, politics can lead to economic growth and rapid change of society. In another word, the political environment has directly impact on the development of culture and Art. This study investigates whether the external factor-political environment affects the process of choreography which should be simply conveying artists¡¦ personal images. Thus artists revise the original ideas and styles of choreography due to this factor. This exploration of the relationship between the change of Taiwan history and the development of Art has been done from the point of view of Art sociology. It uses Cloud Gate and its founder-Lin Huai-Ming as an example. Cloud Gate Dance Company is the first contemporary dance company in Taiwan with the largest scheme and the most well-rounded facilities. The creative ideas of Lin Huai-Ming have profound influences on the style of Cloud Gate Dace Company. Through probing into references and interviews, the author inquires the following facts.1.The influence of Lin Huai-Ming on Cloud Gate Dance Company.2.The relationship between Lin Huai-Ming¡¦s choreography and the political environment.3.Discovering the process of the myth of Cloud Gate established in Taiwan society .
8

Adapting Response Surface Methods for the Optimization of Black-Box Systems

Zielinski, Jacob Jonathan 10 September 2010 (has links)
Complex mathematical models are often built to describe a physical process that would otherwise be extremely difficult, too costly or sometimes impossible to analyze. Generally, these models require solutions to many partial differential equations. As a result, the computer codes may take a considerable amount of time to complete a single evaluation. A time tested method of analysis for such models is Monte Carlo simulation. These simulations, however, often require many model evaluations, making this approach too computationally expensive. To limit the number of experimental runs, it is common practice to model the departure as a Gaussian stochastic process (GaSP) to develop an emulator of the computer model. One advantage for using an emulator is that once a GaSP is fit to realized outcomes, the computer model is easy to predict in unsampled regions of the input space. This is an attempt to 'characterize' the overall model of the computer code. Most of the historical work on design and analysis of computer experiments focus on the characterization of the computer model over a large region of interest. However, many practitioners seek other objectives, such as input screening (Welch et al., 1992), mapping a response surface, or optimization (Jones et al., 1998). Only recently have researchers begun to consider these topics in the design and analysis of computer experiments. In this dissertation, we explore a more traditional response surface approach (Myers, Montgomery and Anderson-Cook, 2009) in conjunction with traditional computer experiment methods to search for the optimum response of a process. For global optimization, Jones, Schonlau, and Welch's (1998) Efficient Global Optimization (EGO) algorithm remains a benchmark for subsequent research of computer experiments. We compare the proposed method in this paper to this leading benchmark. Our goal is to show that response surface methods can be effective means towards estimating an optimum response in the computer experiment framework. / Ph. D.
9

THE SANTA ANA SPECKLED DACE (RHINICHTHYS OSCULUS): PHYLOGEOGRAPHY AND MOLECULAR EVOLUTION OF THE MITOCHONDRIAL DNA CONTROL REGION

VanMeter, James Jay 01 June 2017 (has links)
The purpose of this genetic study of the Santa Ana Speckled Dace Rhinichthys osculus was three-fold. The first goal was to characterize the molecular structure of the mtDNA control region of R. osculus. An 1143 base-pair region of the mitochondrial DNA genome, which included the complete control region was sequenced for all individuals. Analysis of the sequence data revealed that the molecular structure of the speckled dace control region was similar to the molecular structure described for other vertebrate taxa. The speckled dace control region contains three major domains, which vary in base frequency as well as in the frequency of nucleotide polymorphisms. Domain II was observed to be the most conserved, and Domain I was the most variable domain of the control region, in agreement with studies of other vertebrate control regions. The second goal of this study was to ascertain the phylogeny of R. osculus in Southern California in relation to other speckled dace in California. Seventy-four specimens of R. osculus were collected from five different watersheds located in three geographic regions of California: Southern California, the Central California Coast, and the Eastern Desert of the Owens River valley. Phylogenetic analysis of sequence data revealed that the Santa Ana Speckled Dace is a genetically distinct population from R. osculus inhabiting the Central Coast or Eastern Desert regions, which both differ from the Santa Ana Speckled Dace by a genetic distance of more than 7 percent. The Santa Ana Speckled Dace inhabiting the watersheds of Southern California form a reciprocally monophyletic clade with respect to the Central Coast dace and the Eastern Desert dace, which are sister clades to one another. The third goal of this study was to describe the population genetics of R. osculus in Southern California. Population genetic analysis demonstrated that a high degree of geographic population structure exists for the Speckled Dace in California, with 96% of molecular variance attributable to regional differences through isolation by distance. A high degree of population structure also exists among populations within the Southern California region as well. It was found that 45% of molecular variance in the Santa Ana Speckled Dace is attributable to differences among tributaries. This study finds that the distribution of speckled dace in Southern California best fits a model of population structure by individual tributary, with episodes of localized population bottlenecks followed by sudden population expansion, most likely linked to climatic variation. It is proposed the Santa Ana Speckled Dace constitutes an Evolutionarily Significant Unit (ESU) that qualifies it as a separate subspecies on the basis that it is geographically separated from other populations, genetically distinct from other dace populations due to restricted gene flow, and possesses unique phenotypic characteristics. This information suggests conservation and management strategies for the speckled dace populations which remain in existence in Southern California.
10

Short-term response of physical habitat and fish to the addition of large woody debris in two Appalachian Mountain streams

Allen, Kelly Harpster 25 August 2008 (has links)
Large woody debris (LWD) was added to North Fork Stony Creek and North Prong Barbours Creek in southwest Virginia to inlprove fish habitat. The purposes of this study were to monitor stream channel response to the addition of LWD at a stream reach scale and at a local scale around individual logs, to evaluate changes in fish population parameters, and to observe microhabitat availability and use before and after L WD additions. In low-gradient Stony Creek, LWD was effective in modifying fish habitat through the formation of pools, the structuring of poo1/riffle sequences, and the enhancement of channel complexity. New pools formed from the break up of continuous rime habitat, increasing the overall number of habitat units and decreasing mean surface areas. Total pool area increased for both treatment sections, while changing little in the reference section where no logs were added. Localized scour and fill was observed for crosssectional transects around individual logs, creating a more heterogenous environment than in areas without logs. In contrast, physical habitat changed little in moderate-gradient Barbours Creek after L WD was added. An increase in the relative weight of brook trout in Barbours Creek suggested that although minimal channel changes were observed, logs may have increased channel complexity and cover, providing resting areas of lower velocities next to food pathways, which may have lead to decreased energy expenditure. Observations of microhabitat use revealed that unlike adult brook trout, juvenile brook trout used a limited range of depths and velocities. Adult brook trout shifted microhabitat use in response to changes in microhabitat available. Low numbers of fish in Stony Creek may have been related to low pH, but numbers of adult brook trout found in each section increased in 1994. With improved water quality, I believe that fish abundance in Stony Creek would increase through time because of the improved habitat. Although few significant changes were observed for available microhabitat in Stony Creek, changes in physical habitat suggest that over time shifts in microhabitat would be apparent. / Master of Science

Page generated in 0.0563 seconds