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Retrospective Theses and Dissertations

Environmental Sciences

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Full-Text Articles in Life Sciences

The Importance Of Host Fish In Long Range Transport Of Unionids In Large Rivers , Daelyn Adele Woolnough Jan 2006

The Importance Of Host Fish In Long Range Transport Of Unionids In Large Rivers , Daelyn Adele Woolnough

Retrospective Theses and Dissertations

Freshwater mussels (Family: Unionidae) are the most imperiled faunal group in North America, yet little is known about factors that influence their distribution in rivers and lakes---especially over large geographic areas. They have a unique life cycle that includes an obligate parasite stage on fish. Throughout their life spans, long range or upstream transport is principally accomplished during the parasitic stage. This brief parasitic phase has lasting effects on adult mussel ecology---particularly in influencing their distribution. The movement of host fish occurs on large scales (e.g., >100m) and both their distribution and abundance likely contribute to the spatial patterns ...


Behaviorally-Induced Periodic Cooling Of Avian Embryos , Christopher Robin Olson Jan 2006

Behaviorally-Induced Periodic Cooling Of Avian Embryos , Christopher Robin Olson

Retrospective Theses and Dissertations

For many bird embryos, periodic cooling occurs when the incubating adult leaves the nest to forage, but the effects of periodic cooling on embryo growth, yolk use and metabolism are poorly known. To address this question I conducted incubation experiments on eggs of zebra finches (Taeniopygia guttata ) that were frequently cooled and then rewarmed or were allowed to develop at a constant temperature. After 12 days of incubation, embryo mass and yolk reserves were less in eggs that experienced periodic cooling, compared to controls incubated constantly at 37.5°C. Embryos that regularly cooled to 20°C had higher mass-specific ...


Weedy Setaria Species-Group Seed Heteroblasty Blueprints Seedling Recruitment , Kari Ann Jovaag Jan 2006

Weedy Setaria Species-Group Seed Heteroblasty Blueprints Seedling Recruitment , Kari Ann Jovaag

Retrospective Theses and Dissertations

The relationship between weedy Setaria seed dormancy and subsequent behaviors in the soil culminating in seedling recruitment is elucidated. Weedy Setaria seed dormancy capacity heterogeneity (heteroblasty) at the time of dispersal was characterized for 45 locally adapted Setaria populations, as influenced by parental genotype (species, time of embryogenesis) and environment (year, location). Taken together, the 45 responses represented Setaria's "seed dormancy phenotype space". The fate of heteroblastic seed entering the soil post-abscission was studied in four of the populations. When dispersed, heteroblastic Setaria seeds introduced into the soil form long-lived pools with varying cycles of dormancy, germination and death ...


Anuran Community Structure And Wetland Occupancy Along An Urban-Rural Gradient In Central Iowa, Usa , Finn Cooper Pillsbury Jan 2006

Anuran Community Structure And Wetland Occupancy Along An Urban-Rural Gradient In Central Iowa, Usa , Finn Cooper Pillsbury

Retrospective Theses and Dissertations

Urbanization has been cited as an important factor in worldwide amphibian declines. Although recent work has illustrated the influence of broad-scale ecological patterns and processes on amphibian populations, little is known about the relative importance of wetland habitat and landscape context on the distribution, abundance, and diversity of anurans in urban landscapes. We therefore examined patterns of anuran community structure and wetland occupancy along an urban-rural gradient in central Iowa, USA. Landscape fragmentation had the strongest influence on anuran community structure, influencing most the abundance of species that use upland habitats outside the breeding season. Urban habitat loss and fragmentation ...


Corridors And Some Ecological And Evolutionary Consequences Of Connectivity , John Lee Orrock Ii Jan 2004

Corridors And Some Ecological And Evolutionary Consequences Of Connectivity , John Lee Orrock Ii

Retrospective Theses and Dissertations

By connecting disjunct patches, corridors may offset the effects of fragmentation by promoting gene flow and population persistence. However, the ultimate effect of corridors on a focal species may hinge upon two considerations: how corridors may affect ecological interactions that impinge upon that species, and how corridors might affect the fixation of novel alleles that ultimately determine fitness and persistence. Using an experimental landscape, I show that corridor-mediated changes in patch shape change seed predation in connected and unconnected patches, and shift the behavior, abundance, and distribution of seed predators. Rodent seed predators removed more seeds in connected patches, arthropod ...


Spatial And Temporal Scales Of Distribution And Demography In Breeding Songbirds: Implications Of Habitat Fragmentation And Restoration , Robert J. Fletcher Jr. Jan 2003

Spatial And Temporal Scales Of Distribution And Demography In Breeding Songbirds: Implications Of Habitat Fragmentation And Restoration , Robert J. Fletcher Jr.

Retrospective Theses and Dissertations

Tallgrass prairie has declined throughout the midwestern United States during the past two centuries, and migratory birds breeding in these habitats have also experienced precipitous population declines. One conservation strategy used to mitigate the effects of habitat loss and fragmentation is habitat restoration. I studied how both habitat fragmentation and restoration affect songbird populations breeding in grassland and wetland habitats in northern Iowa, 1999--2002. Most grassland birds tended to be less abundant near edges, yet birds avoided woodland edges more so than other types of edges. Edge avoidance could not be explained by changes in habitat structure. For Bobolinks (Dolichonyx ...


Evaluation Of A Collaborative Approach To Mediate Conflict Between Parties With Interests In Wildlife And Livestock In Colorado , Gina Marie Mcandrews Jan 2001

Evaluation Of A Collaborative Approach To Mediate Conflict Between Parties With Interests In Wildlife And Livestock In Colorado , Gina Marie Mcandrews

Retrospective Theses and Dissertations

The Habitat Partnership Program (HPP) is a collaborative initiative of the Colorado Division of Wildlife and the Colorado Cattleman's Association. The program consists of 15 committees, distributed over western Colorado, representing the interests of public resource managers, livestock growers and hunters. Through partnerships and projects, each committee strives to reduce fence damage and forage loss from big game activity. Information gathered from interviews, documents, projects and observation was used to assess the effectiveness of HPP in meeting its stated goals: resolve conflicts, improve ecosystem health, raise local knowledge about resource management and improve communication and understanding. Over seven years ...


Maternal Effects In The American Coot: Consequences For Offspring Growth And Survival , Wendy Louise Reed Jan 2000

Maternal Effects In The American Coot: Consequences For Offspring Growth And Survival , Wendy Louise Reed

Retrospective Theses and Dissertations

Life history theory predicts, and empirical studies indicate, that egg size can be an important determinant of fitness for a variety of species. The premise of these studies is that energy for reproduction is limited, and as parents increase energy investments in individual offspring, those offspring should accrue fitness benefits. The work presented in this dissertation addresses how energetic and hormonal resources vary with egg size and the consequences of these investments for offspring growth and survival in a free-living population of American coots (Fulica americana). Eggs vary in size at three levels: at the population level, among females and ...


Floristic Analysis Of Central Iowa Woodlands, And Comparison Of Reproduction And Regeneration In Common And Restricted Herbaceous Species , Catherine Mary Mabry Jan 2000

Floristic Analysis Of Central Iowa Woodlands, And Comparison Of Reproduction And Regeneration In Common And Restricted Herbaceous Species , Catherine Mary Mabry

Retrospective Theses and Dissertations

I studied the distribution and abundance of the plant species of forests in central Iowa, emphasizing the effect of cattle grazing on the vegetation. I used traits to identify groups of species that may function as guilds, and to address whether species' frequency was related to traits. To understand the difference between species that were common compared to those relatively less common (restricted species), I examined whether the two groups differed in reproductive output and allocation, seed viability, and seedling emergence;Understory species and canopy trees were generally distributed along the same environmental gradients. These were landform, soil phosphorous and ...


The Influence Of Habitat Features On Grassland Birds Nesting In The Prairie Pothole Region Of North Dakota , David Joseph Horn Jan 2000

The Influence Of Habitat Features On Grassland Birds Nesting In The Prairie Pothole Region Of North Dakota , David Joseph Horn

Retrospective Theses and Dissertations

Results of habitat fragmentation studies on grassland and wetland birds are not consistent. Some studies have found positive relationships among abundance, nest success, field size, and distance to edges, whereas others have found no relationship. One reason for differing results may be the landscape composition in which the study took place. I examined how landscape composition influenced relations among: (1) occurrence and abundance of grassland songbirds and field size, and (2) nest success of ducks, field size, and edges. I also investigated the effects of mowing on grassland songbirds, and how landscape features, such as amount of perennial grassland, and ...


The Use Of Anuran Larvae To Determine Chronic And Acute Toxicological Effects From Exposure To Atrazine And Metolachlor , Linda Suzanne Gucciardo Jan 1999

The Use Of Anuran Larvae To Determine Chronic And Acute Toxicological Effects From Exposure To Atrazine And Metolachlor , Linda Suzanne Gucciardo

Retrospective Theses and Dissertations

This research investigated the effects of chronic exposure of amphibian tadpoles and acute exposure of embryos to the agricultural chemical atrazine;Tadpoles were chronically exposed from the first feeding stage through metamorphosis to three levels of atrazine. Concentrations of 30, 300 and 600 mug/L reflect exposures likely to occur in streams, wetlands and temporary waters near croplands. Cricket frogs (Acris crepitans), wood frogs (Rana sylvatica) and northern leopard frogs (R. pipiens ) were evaluated on rate of growth, days to metamorphosis, metamorphic success, and juvenile weight and length. A repeated measures ANOVA evaluated the rate of growth (increase in SVL ...


Gene Flow At A Snail's Pace: Phylogeography And Conservation Genetics Of Relict Populations Of The Iowa Pleistocene Snail , Tamara Kay Ross Jan 1998

Gene Flow At A Snail's Pace: Phylogeography And Conservation Genetics Of Relict Populations Of The Iowa Pleistocene Snail , Tamara Kay Ross

Retrospective Theses and Dissertations

The Iowa Pleistocene snail, Discus macclintocki, is a federally endangered land snail found only in northeast Iowa and northwestern Illinois. This species is believed to be a glacial relict with populations isolated for the last 16,000 years. In this study, I investigated the amount of genetic variation within, and the gene flow among, ten isolated populations of the Iowa Pleistocene snail, Discus macclintocki (Baker). I sequenced part of the 16s region of the mitochondrial DNA from 175 snails. Populations clustered clearly by watershed, suggesting that flooding events may have been the historical avenue of gene flow rather than overland ...


Butterflies In The Highly Fragmented Prairies Of Central Iowa: How The Landscape Affects Population Isolation, Leslie Ries Jan 1998

Butterflies In The Highly Fragmented Prairies Of Central Iowa: How The Landscape Affects Population Isolation, Leslie Ries

Retrospective Theses and Dissertations

Ever since MacArthur and Wilson presented the Theory of Island Biogeography in 1963, there has been considerable concern about the ability of a system of isolated reserves to retain species diversity or viable populations over extended periods of time. Despite this interest, very little is known about how readily individuals move around in their landscape. Edges and corridors have both been targeted as landscape features that may have important consequences for directing movement and thereby affecting isolation. Edges may form a barrier to movement reducing the probability that an individual will leave a patch. For individuals that have left, they ...


The Effects Of Intensive Agricultural Land-Use Practices On Small Streams In Northwestern Iowa, Jeffery Allen Kopaska Jan 1997

The Effects Of Intensive Agricultural Land-Use Practices On Small Streams In Northwestern Iowa, Jeffery Allen Kopaska

Retrospective Theses and Dissertations

Intensive agricultural land use dominates Iowa's landscape, leading to degradation of the environmental quality of Iowa's land, water, and biota. This study was designed to determine how land use practices affect stream environments in a typical Iowa agricultural landscape. Thirteen first order streams and their watersheds within the Northwest Iowa landform region were studied. Corn and soybeans are grown on the flat headlands of this area, while the steeper terrain is wooded or pastured. Steep erosional topography occurs in association with the Little Sioux River valley. Watershed areas ranged from 72 to 1030 hectares. Geographic Information Systems analysis ...


Maternal Expenditure And The Resolution Of Adult-Offspring Conflict In The South American Guanaco , Ronald James Sarno Jan 1997

Maternal Expenditure And The Resolution Of Adult-Offspring Conflict In The South American Guanaco , Ronald James Sarno

Retrospective Theses and Dissertations

I examined patterns of pre-/post-birth maternal expenditure in the polygynous guanaco, Lama guanicoe, in Torres del Paine National Park, Chile from November 1990 to December 1993. Because of presumed greater variance in reproductive success of males of polygynous species, theoreticians have hypothesized that greater energy investment in sons might improve their competitive abilities and lead to increased reproductive success. Thus, it might be adaptive for parent(s) to invest more energy in sons than daughters. The period of parental care in guanacos is also punctuated by an interval of intense adult-offspring conflict. Adult males seasonally defend feeding territories and ...


Relationship Of Landscape Structure To Ring-Necked Pheasant Population Dynamics In Northern Iowa , Richard Albert Schmitz Jan 1997

Relationship Of Landscape Structure To Ring-Necked Pheasant Population Dynamics In Northern Iowa , Richard Albert Schmitz

Retrospective Theses and Dissertations

I studied demographic processes that operate on individual animals as a means to understand the relationship of landscape structure to population size and survival. I applied the idea of risk-sensitivity to habitat selection by examining the demographic effects on an animal population in which individuals select from two habitats that have similar mean values for reproductive output but differ in the variance of reproductive output. I conducted simulations using a source-sink population model to show that population size increased with increased variation in habitat quality. I then looked at how landscape heterogeneity was related to ring-necked pheasant (Phasianus colchicus) demography ...


The Role Of Arbuscular Mycorrhizal Fungi In Prairie Wetlands , Paul Robert Wetzel Jan 1996

The Role Of Arbuscular Mycorrhizal Fungi In Prairie Wetlands , Paul Robert Wetzel

Retrospective Theses and Dissertations

Research on arbuscular mycorrhizal fungi (AMF) suggests that their effect on plant growth is a continuum that changes from positive to negative along environmental gradients as conditions for plant growth improve. Prairie wetlands were used to test this mycorrhizal continuum model. First, three saline and three freshwater wetlands were surveyed for AMF, to investigate the hypothesis that AMF colonization would be greater in wetlands with high soil salinity, lower nutrient levels, and during periods of drought. Second, a greenhouse experiment on Carex stricta and Calamagrostis canadensis tested whether AMF improved plant growth and nutrient uptake under five hydrologic regimes. Third ...


A Natural Area Inventory Of Ames, Iowa , William Russell Norris Jan 1995

A Natural Area Inventory Of Ames, Iowa , William Russell Norris

Retrospective Theses and Dissertations

Perhaps no state in the Union has suffered such widespread degradation of its natural vegetation as Iowa. Tallgrass prairie (including wet prairie communities, often considered to be wetlands) once covered at least 85% of this state's land area, but more than 99.9% of Iowa's original grasslands have fallen victim to the plow (Smith 1990). Wetlands once covered 11.1% of Iowa's landscape (Dahl 1990), but virtually all of these have been drained to make way for rowcrops (wetlands now cover only 1.2% of Iowa's landscape). Roughly 12 to 20% of the state was covered ...


Territorial Behavior Of The Red Admiral Butterfly, Vanessa Atalanta (L.) (Lepidoptera: Nymphalidae) , Royce Justin Bitzer Jan 1995

Territorial Behavior Of The Red Admiral Butterfly, Vanessa Atalanta (L.) (Lepidoptera: Nymphalidae) , Royce Justin Bitzer

Retrospective Theses and Dissertations

This study of territorial behavior in the nymphalid butterfly Vanessa atalanta examines a number of behavioral and climatic factors shaping how, when, and for how long males maintain territories during the late afternoons of late spring and summer. Territorial V. atalanta males were observed on the Iowa State University campus from early April/early May to late August/early September from 1987 to 1992 on a total of 224 days. Microclimatic conditions were simultaneously recorded with automatic datalogging equipment. Males started territorial activity later on warmer days and when the ground was cooler, under all types of cloud cover. Although ...


Structure Of Breeding-Bird Communities On Natural And Restored Iowa Wetlands, Julie Ann Schreiber Jan 1994

Structure Of Breeding-Bird Communities On Natural And Restored Iowa Wetlands, Julie Ann Schreiber

Retrospective Theses and Dissertations

No abstract provided.


Evaluation Of Factors Influencing Grit Use By Birds , James Paul Gionfriddo Jan 1994

Evaluation Of Factors Influencing Grit Use By Birds , James Paul Gionfriddo

Retrospective Theses and Dissertations

Avian grit use was investigated by examining the gizzard contents of free-ranging birds and by conducting aviary experiments with captive birds. Free-ranging Iowa House Sparrows (Passer domesticus) were captured, and their gizzard grit was compared by sex, season, and diet. Males and females did not differ in mean grit amounts (overall x = 580 particles) or sizes, (overall x = 0.5 mm). Birds captured during March and August contained more grit than birds captured during September through February (x = 674 vs. 477). Gizzards containing >75% animal material (insects) had more grit than those containing, >75% plant food (x = 681 vs. 531 ...