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  • 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

From Genes to Stasis: A Hierarchical Study of Phenotypic Variation in Drosophila Melanogaster Wing Shape

Unknown Date (has links)
A great challenge that biology faces is in integrating phenomena from different scales. On the micro scale of the spectrum, we can measure subcellular processes, like gene expression and regulation. On the macro scale, we can measure species level variation, ecological interactions, and the like. The challenge biology faces is in following the causal threads that lead individuals, populations, and ultimately, species to the variation in traits that we see in nature. The idea that there are cascades of causality that reduce to a microscopic scale is often referred to as the Genotype to Phenotype map (Houle and Govindaraju 2010). The Genotype to Phenotype map is ultimately a problem of measurement; what do we need to measure at each scale of interest in order to understand and, more importantly, predict variation elsewhere on the spectrum? This thesis is focused on two parts of the genotype-phenotype spectrum. The first chapter focuses on the macro scale, specifically on how traits maintain stasis across species. Here we use Drosophila melanogaster wing shape as a model to test whether stasis is explained by constraint or by stabilizing selection. We test for constraint with an artificial selection experiment on wing shape. We then test for stabilizing selection by measuring flight differences among selected and unselected flies and by testing for mate preference. In the second chapter, I focus on the micro scale by describing a method to measure the spatial properties of gene expression patterns. Quantitative measures of gene expression currently focus on mutations in the genome and/or the magnitude of expression. This ignores the spatial components of gene activity that are critical in the formation of pattern and the maintenance of growth during development. I describe methods to measure the spatial characteristics of genes that form discrete and continuous patterns of expression. I then give three examples of the method by quantitatively disrupting three genes and estimating the effects on a discrete and a continuous expression pattern. / A Thesis submitted to the Department of Biological Science in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester, 2014. / November 04, 2014. / Includes bibliographical references. / David C. Houle, Professor Directing Thesis; Wu-Min Deng, Committee Member; Michelle N. Arbeitman, Committee Member.
2

The bio-geomorphological evolution of a former flood tidal delta (Bird Island) in the Murray Mouth estuary of South Australia

James, Kristine January 2004 (has links)
Bird Island is a former flood tide delta occurring in the mouth of the River Murray, Encounter Bay, South Australia. The island has experienced a rapid development history; in around 60 years the formerly ephemeral deltaic deposits have rapidly become stabilised, forming a permanent island approximately 1 km in diameter. / It has been possible to place tight time restraints on the progressive development of Bird Island over this 60 year period. Its sand dunes and marshes of different ages can be distinguished clearly from an analysis of successive aerial photographs. Evidence suggests they represent different phases in the growth and development of the island, resulting from an interplay of factors including the position and migration of the Murray Mouth relative to the island as well as the availability of sediment and conditions conducive to aeolian sand transport. / The landforms of Bird Island present a unique opportunity for the assessment and study of progressive plant colonisation and succession on a pristine landscape in a coastal/estuarine setting. Bird Island comprises 19 different dune and marsh vegetation types. Research has identified several trends suggesting that the environmental gradients associated with the marsh-dune landforms has influenced some characteristics of species distribution. It also appears that in a general way, species distributions may represent succession on the sand dunes, but this was not as clearly demonstrated across the marshes of different ages on Bird Island. / Research suggests that the construction of the lower River Murray barrages in 1940, which has reduced the median annual flow to the estuary by nearly 75%, and has reduced the tidal prism by up to 90%; has facilitated the development of Bird Island. Bird Island contributed to the closure of the mouth of the River Murray in 1981; inlet behaviour not demonstrated in the 100 years prior to barrage construction according to the results of this research. / The continuing development of Bird Island suggests considerable potential for more blockages in the future. The continuing sedimentation in the Murray Mouth reflects the inability of the current flow regime and marine processes in maintaining the mouth as they did prior to the construction of regulatory works on the Lower River Murray. / Thesis (MApSc(EnvironmentRecreationMg))--University of South Australia, 2004
3

The bio-geomorphological evolution of a former flood tidal delta (Bird Island) in the Murray Mouth estuary of South Australia

James, Kristine January 2004 (has links)
Bird Island is a former flood tide delta occurring in the mouth of the River Murray, Encounter Bay, South Australia. The island has experienced a rapid development history; in around 60 years the formerly ephemeral deltaic deposits have rapidly become stabilised, forming a permanent island approximately 1 km in diameter. / It has been possible to place tight time restraints on the progressive development of Bird Island over this 60 year period. Its sand dunes and marshes of different ages can be distinguished clearly from an analysis of successive aerial photographs. Evidence suggests they represent different phases in the growth and development of the island, resulting from an interplay of factors including the position and migration of the Murray Mouth relative to the island as well as the availability of sediment and conditions conducive to aeolian sand transport. / The landforms of Bird Island present a unique opportunity for the assessment and study of progressive plant colonisation and succession on a pristine landscape in a coastal/estuarine setting. Bird Island comprises 19 different dune and marsh vegetation types. Research has identified several trends suggesting that the environmental gradients associated with the marsh-dune landforms has influenced some characteristics of species distribution. It also appears that in a general way, species distributions may represent succession on the sand dunes, but this was not as clearly demonstrated across the marshes of different ages on Bird Island. / Research suggests that the construction of the lower River Murray barrages in 1940, which has reduced the median annual flow to the estuary by nearly 75%, and has reduced the tidal prism by up to 90%; has facilitated the development of Bird Island. Bird Island contributed to the closure of the mouth of the River Murray in 1981; inlet behaviour not demonstrated in the 100 years prior to barrage construction according to the results of this research. / The continuing development of Bird Island suggests considerable potential for more blockages in the future. The continuing sedimentation in the Murray Mouth reflects the inability of the current flow regime and marine processes in maintaining the mouth as they did prior to the construction of regulatory works on the Lower River Murray. / Thesis (MApSc(EnvironmentRecreationMg))--University of South Australia, 2004
4

Representing science education in UK newspapers : a case study on the controversy surrounding teaching the theory of evolution and creationism in science classes.

Allgaier, Joachim. January 2007 (has links)
Thesis (Ph. D.)--Open University. BLDSC no. DXN116690.
5

Natural hybridization and speciation in toads of the Anaxyrus americanus group

Fontenot, Brian E. January 2009 (has links)
Thesis (Ph.D.) -- University of Texas at Arlington, 2009.
6

Natural selection theory in non-majors' Biology : instruction, assessment, and conceptual difficulty /

Anderson, Dianne L. January 2003 (has links)
Thesis (Ph. D.)--University of California, San Diego and San Diego State University, 2003. / Vita. Includes bibliographical references (leaves 219-228).
7

The preservation of duplicate genes by complementary, degenerative mutations and the origin of organismal complexity /

Force, Allan Gwynne, January 2000 (has links)
Thesis (Ph. D.)--University of Oregon, 2000. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 150-160). Also available for download via the World Wide Web; free to University of Oregon users.
8

Distance metrics for phylogenies with non-uniform degrees /

Hon, Wing-kai. January 2000 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 50-52).
9

On the role of historical constraint in evolution an emphasis in salamander evolution /

Eastman, Jonathan Michael. January 2010 (has links) (PDF)
Thesis (Ph. D.)--Washington State University, May 2010. / Title from PDF title page (viewed on July 1, 2010). "Department of Biological Sciences." Includes bibliographical references.
10

Formal evolutionary modeling and the problems of political science /

Smirnov, Oleg. January 2005 (has links)
Thesis (Ph. D.)--University of Oregon, 2005. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 113-131). Also available for download via the World Wide Web; free to University of Oregon users.

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