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Full-Text Articles in Animal Sciences

Investigating Microbiomes And Developing Direct-Fed Microbials To Improve Cattle Health, Alison C. Bartenslager Apr 2020

Investigating Microbiomes And Developing Direct-Fed Microbials To Improve Cattle Health, Alison C. Bartenslager

Department of Animal Science: Dissertations, Theses, and Student Research

Over the last decade, global beef production has increased to meet the protein needs of the growing population. As a result, the intensification of beef cattle production systems has resulted in broad spectrum prophylactic use of antibiotics and growth promoting agents. With increased concern around antimicrobial resistance (AMR) and emergence of novel pathogenic strains of bacteria, it is critical to understand disease progression and associated changes in the microbiome to develop novel therapeutic alternatives to reduce antibiotic use and control disease. One such approach that is currently being investigated is the development of novel direct-fed microbial strains to outcompete pathogens …


Heat Stress-Induced Deficits In Growth, Metabolic Efficiency, And Cardiovascular Function Coincided With Chronic Systemic Inflammation And Hypercatecholaminemia In Ractopamine-Supplemented Feedlot Lambs: Atypical Cyclicity At Puberty In Beef Cows Is Associated With Early Deficits In Muscling, Metabolic Indicators, And Myoblast Function In Offspring But Does Not Impact Feedlot Performance, Rebecca M. Swanson Apr 2020

Heat Stress-Induced Deficits In Growth, Metabolic Efficiency, And Cardiovascular Function Coincided With Chronic Systemic Inflammation And Hypercatecholaminemia In Ractopamine-Supplemented Feedlot Lambs: Atypical Cyclicity At Puberty In Beef Cows Is Associated With Early Deficits In Muscling, Metabolic Indicators, And Myoblast Function In Offspring But Does Not Impact Feedlot Performance, Rebecca M. Swanson

Department of Animal Science: Dissertations, Theses, and Student Research

Our 1st study evaluated the effects of b-adrenergic agonist (ractopamine) supplementation on growth, health, and wellbeing in heat-stressed feedlot wethers. Chronic heat stress impaired growth, metabolism, and wellbeing even when the impact of reduced feed intake was eliminated by pair-feeding. We observed systemic inflammation and hypercatecholaminemia that were likely mediators of these deficits. Moreover, ractopamine did not diminish any wellbeing indicators and improved muscle growth without worsening the effects of heat stress.

Our 2nd study assessed the effects of pubertal cyclicity (weaning to 1st breeding) in cows on myoblast-mediated muscle growth, metabolism, and growth efficiency of their …


Una Evaluación De La Evolución Y El Futuro De La Vigilancia De La Pesca Ilegal En Antártida Bajo La Ccrvma, Courtney Jacobs Apr 2020

Una Evaluación De La Evolución Y El Futuro De La Vigilancia De La Pesca Ilegal En Antártida Bajo La Ccrvma, Courtney Jacobs

Independent Study Project (ISP) Collection

Este documento de investigación evalúa el tema de la pesca ilegal en el Área de la Convención de la Antártida establecida por la Comisión para la Conservación de los Recursos Vivos Marinos Antárticos (CCRVMA). El enfoque general de esta investigación es evaluar la capacidad de la Comisión para abordar la preocupación de la pesca ilegal en el Área de la Convención. Este objetivo se persigue examinando tres subpreguntas: ¿cómo ha evolucionado la pesca ilegal en el Área de la Convención a lo largo del período estudiado, qué medidas ha tomado con éxito la Comisión con respecto al monitoreo y cumplimiento …


Physiological And Behavioral Effects Of Climate Change On Wildlife: An Introduction And Overview, Andy Clarke Apr 2020

Physiological And Behavioral Effects Of Climate Change On Wildlife: An Introduction And Overview, Andy Clarke

Senior Honors Theses

Planetary environmental system changes have been recorded and documented for several decades. Fluctuations that were first noticed in atmospheric carbon-dioxide levels have now extended into global pattern changes. Climatic variations that were initially non-threatening variabilities have since been observed creating significant biological influences. The results and evidence of the effects of worldwide environmental climate change on wildlife and biotic environments are worth examining because of the impacts it has on the planet. These climatic effects extend from changes in distribution and diversity patterns of terrestrial mammals to sea-life impacts and recovery trends. Possible wildlife benefits may include increased humidity and …


West Coast Rock Lobster Whale Entanglement Mitigation Workshop, Jason How, L Orme, Graeme Baudains, Pia Dobson, M Taylor, Simon De Lestang Apr 2020

West Coast Rock Lobster Whale Entanglement Mitigation Workshop, Jason How, L Orme, Graeme Baudains, Pia Dobson, M Taylor, Simon De Lestang

Fisheries Occasional Publications

No abstract provided.


Development And Diagnostic Application Of Monoclonal Antibodies Against Swine Acute Diarrhea Syndrome Coronavirus (Sads-Cov), Molly Kroeger Apr 2020

Development And Diagnostic Application Of Monoclonal Antibodies Against Swine Acute Diarrhea Syndrome Coronavirus (Sads-Cov), Molly Kroeger

Schultz-Werth Award Papers

Swine Acute Diarrhea Syndrome Coronavirus (SADS-CoV) is a member of the Coronaviridae family. The virus is associated with severe small intestine inflammation and diarrhea in suckling piglets. In 2017, SADS-CoV was first detected and identified as the causative agent of a devasting swine disease outbreak in southern China. Routine monitoring and early detection of the source of infection is therefore integral to the prevention and control of a SADS-CoV outbreak in the United States. However, the United States does not currently have any diagnostic or surveillance tests to identify this emerging disease. To address these industry needs, we developed monoclonal …


Evaluation Of Anterior Pituitary Leptin Receptor Expression In Pregnant And Non-Pregnant Gilts, Juliana Pederson, Jeffrey Clapper Apr 2020

Evaluation Of Anterior Pituitary Leptin Receptor Expression In Pregnant And Non-Pregnant Gilts, Juliana Pederson, Jeffrey Clapper

Schultz-Werth Award Papers

Successful reproduction in porcine depends on the coordinated synthesis and release of several hormones from the hypothalamus and anterior pituitary gland. Leptin, a hormone produced from adipocytes, interacts with other specific reproductive hormones and affects the reproductive success in swine. However, the full extent of leptin’s impact is unclear. This experiment sought to examine the difference in expression between the anterior pituitary gland leptin receptors in pregnant and non-pregnant pigs to confer the impact leptin has on reproductive success. Twentyfour crossbred gilts of similar age and weight had their estrus cycles synchronized and then were bred via artificial insemination. The …


Understanding Sportsperson Retention And Reactivation Through License Purchasing Behavior, Matthew P. Hinrichs, Nathaniel B. Price, Matthew P. Gruntorad, Kevin L. Pope, Joseph J. Fontaine, Christopher J. Chizinski Apr 2020

Understanding Sportsperson Retention And Reactivation Through License Purchasing Behavior, Matthew P. Hinrichs, Nathaniel B. Price, Matthew P. Gruntorad, Kevin L. Pope, Joseph J. Fontaine, Christopher J. Chizinski

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Most state and provincial fish and wildlife agencies have access to important information about patterns in sportsperson participation through their license databases. Using transaction data from Nebraska Game and Parks Commission’s electronic hunting and fishing license system, we tracked license purchases of Nebraska, USA, resident license holders in 2010 through 2017. We categorized sportspersons by gender and yearly purchases as hunting only (Hunter), fishing only (Angler), a combination of hunting and fishing (Hunter–Angler), or no purchases (Inactive). The probability of movement among active sportsperson groups was limited and varied little based on initial group participation. The Angler group had the …


The Impact Of Nicotine Accumulation Exposure On Lithobates Catebeianus Larvae Mortality, Luke Micek Apr 2020

The Impact Of Nicotine Accumulation Exposure On Lithobates Catebeianus Larvae Mortality, Luke Micek

UCARE: Research Products

Cigarette butts are the most littered item in the world and contain over 4,000 chemicals, including the organic compound nicotine (Slaughter et al. 2011). Billions of cigarette butts are littered each year which may wash into bodies of water, impacting the local wildlife. To determine how introduced chemicals impact the environment, it is important to study its effects on indicator species. Amphibians, such as Lithobates catebeianus, act as indicator species due to their extreme sensitivity to chemical changes in its environment. The purpose of this research project was to obtain data to help determine the impact nicotine accumulation has …


Grackles, Michael J. Bodenchuk, David L. Bergman Apr 2020

Grackles, Michael J. Bodenchuk, David L. Bergman

Wildlife Damage Management Technical Series

Numbering in the tens of millions of birds, grackle populations in North America can cause a variety of conflicts with people. Grackles eat agricultural crops and livestock feed, damage property, spread pathogens, and collide with aircraft. Their large roosts can be a nuisance in urban and suburban areas. A combination of dispersal techniques, exclusion, and lethal removal may help to reduce grackle damage.

Grackles adapt easily to human-dominated environments, and exploit human food and other features of human landscapes. Thus, an integrated damage management approach to grackle damage focuses on reducing and eliminating the damage, rather than simply controlling grackle …


Constructing A Series Of Informative Videos And Building Social Media Platforms For Save One Soul Animal Rescue League, Cassandra Munroe Apr 2020

Constructing A Series Of Informative Videos And Building Social Media Platforms For Save One Soul Animal Rescue League, Cassandra Munroe

Senior Honors Projects

Approximately six million animals enter shelters each year. Of those six million animals, about two million are killed each year. Due to the lack of spaying and neutering and overcrowding, especially in the southern states of the U.S., the population of animals in high-kill shelters is alarming. Save One Soul Animal Rescue League (SOSARL) is a volunteer-driven non-profit dog rescue founded and based in Rhode Island. The mission of SOSARL is to permanently rehome homeless, neglected, abandoned, and at-risk dogs. The majority of the dogs rehomed by SOSARL are transported from overcrowded high-kill shelters in the Southern U.S. or from …


Calf Heath And Oxidative Stress, Samantha Cardin Apr 2020

Calf Heath And Oxidative Stress, Samantha Cardin

Senior Honors Projects

In recent years, beef cattle operations such as farms and ranches in the U.S. have surpassed 900,000 and have been steadily increasing. With this rise in the beef industry, comes a greater concern for calf health since it has huge impacts on production and viability. There are multiple different factors that can affect calf health ranging from the intrauterine environment to conditions early on post parturition. An improper maternal environment during pregnancy can impact fetal growth because it can decrease the amount of nutrients reaching the calf. This can lead to low birth weights and undeveloped organ systems. Additionally, if …


Miss Independent: Social Group Composition Influences Spatial Patterns In A Female Lion, Andrew Mayfield, Abigail Smith Apr 2020

Miss Independent: Social Group Composition Influences Spatial Patterns In A Female Lion, Andrew Mayfield, Abigail Smith

Student Scholars Day Posters

The introduction of a new animal to a social group can cause individual zoo animals to alter their behavior. In 2019, a male lion was successfully introduced to an adult female at John Ball Zoo, after previously being exhibited with her sister in 2018. A second, older male continued to be exhibited alone, alternating with the pair in the same enclosure. Our study objective was to compare differences in behavior between 2018 and 2019 for the female (“experimental” animal whose social group changed) and the solitary male (“control” animal whose social group did not change). We used Zoomonitor to record …


Thing 1 And Thing 2 Are In A New Zoo: Changes In Behavior Of Amur Tigers Following Introduction To John Ball Zoo, Caitlin Gerke, Faith Hensley Apr 2020

Thing 1 And Thing 2 Are In A New Zoo: Changes In Behavior Of Amur Tigers Following Introduction To John Ball Zoo, Caitlin Gerke, Faith Hensley

Student Scholars Day Posters

Animals alter their behavior in response to changes in their environment such as alterations to their enclosure, social group, or husbandry routine. In 2018, two related, young adult Amur tigers (Panthera tigris altaica) were transferred to the John Ball Zoo (JBZ). The male siblings were given access to a spacious, wooded outdoor enclosure (area = 920 m²). We used Zoomonitor in 2018 and 2019 to conduct focal-animal sampling of the two males. We recorded state behaviors in 30 sec intervals of scan sampling, and all occurrences of event behaviors, both during 30 min sampling sessions. Our study objective …


The Impacts Of Large Carnivores On Human Livelihood: The Illusion Of Carnivore Conflict, Costs Of Coexistence, And Strategies For Mitigation, Elisabeth Russell Apr 2020

The Impacts Of Large Carnivores On Human Livelihood: The Illusion Of Carnivore Conflict, Costs Of Coexistence, And Strategies For Mitigation, Elisabeth Russell

Senior Honors Theses

Incidents of what is commonly referred to as human-carnivore conflict (HCC) are increasing. Examples include livestock depredation and carnivores attacking humans. Since HCC occurs most frequently where humans and carnivores commonly inter-mix – near the periphery of human habitations – habitat loss and fragmentation may contribute to the rise of HCC, amongst other factors. Although HCC cannot be eliminated, it can be reduced by well-planned and implemented strategies. These strategies must approach the conflict holistically and address both the animal and the human sides of the problem. Since humans rely on the healthy functioning of the ecosystem for survival, implementing …


Macroinvertebrate Community And Temperature Changes In A Michigan Stream, Nyika Campbell Apr 2020

Macroinvertebrate Community And Temperature Changes In A Michigan Stream, Nyika Campbell

Independent Study Project (ISP) Collection

As the climate warms, global biodiversity is plummeting and extinction rates are rising (Jenkins, 2003). Freshwater ecosystems specifically are experiencing huge losses in diversity (Jenkins, 2003; Ormerod et al., 2010; Collier et al., 2016). Conservation of invertebrates is particularly urgent because they are foundational to the trophic systems in streams and lakes, comprising 95% of all species on earth (Titley et al., 2017), and over 60% of biodiversity in freshwater ecosystems (Collier et al., 2016). Through analysis of both my own field measurements and historical data I seek to gain a preliminary understanding of temperature and macroinvertebrate community changes that …


Parásitos Gastrointestinales De Tierra Del Fuego, Argentina, Sarah Martínez Apr 2020

Parásitos Gastrointestinales De Tierra Del Fuego, Argentina, Sarah Martínez

Independent Study Project (ISP) Collection

Este trabajo intentó encontrar helmintos comunes, especialmente compartidos, en cuatro carnívoros patagónicos del sur con distribuciones geográficas superpuestas y dos carnívoros patagónicos del norte, y esbozar el análisis fecal y los métodos de identificación morfológica para futuros investigadores. El estudiante encontró solo un parásito helminto compartido entre cualquier otra especie y la nutria nativa del sur del río, a pesar de una superposición en el hábitat con el visón americano invasivo, pero esto puede deberse a un bajo recuento de estudios regionales previos de helmintos en cualquiera de las especies. Se encontraron múltiples parásitos en las cuatro especies hospederas de …


Surviving Under The Reign Of El Niño Southern Oscillation: An Analysis Of The Effects Of Extreme El Niño Events On The Oceanographic And Biological Environment Of The Galápagos Islands, Ava Mcilvaine Apr 2020

Surviving Under The Reign Of El Niño Southern Oscillation: An Analysis Of The Effects Of Extreme El Niño Events On The Oceanographic And Biological Environment Of The Galápagos Islands, Ava Mcilvaine

Independent Study Project (ISP) Collection

El Niño Southern Oscillation (ENSO) is commonly known as the atmospheric and oceanographic powerhouse of the Southern Pacific Ocean. From phytoplankton to apex predators, ENSO controls the stability of species’ populations within this biodiverse ocean environment. El Niño’s 9-15 month alteration of the heat storage in the tropical Pacific drastically shifts the temperature, nutrient, and circulation gradient its marine life is accustomed to. A single degree change in the ocean’s surface layer temperature can have large consequences for marine species, and El Niño is commonly associated with Sea Surface Temperature Anomalies (SSTAs) between 2°- 6° Celsius. The potential danger El …


An Apex Predator In Peril In The Western Lowlands Of Ecuador: Mapping The Population Distribution Of Harpy Eagles (Harpia Harpyja) In A Highly Deforested Region, Samuel Zhang Apr 2020

An Apex Predator In Peril In The Western Lowlands Of Ecuador: Mapping The Population Distribution Of Harpy Eagles (Harpia Harpyja) In A Highly Deforested Region, Samuel Zhang

Independent Study Project (ISP) Collection

The Harpy Eagle (Harpia harpyja) is a highly threatened bird of prey in Ecuador. While they are already elusive in the Ecuadorian Amazon, they are even lesser known in the coastal lowlands, and their existence is threatened by rapid deforestation. This study mapped their potential distribution by examining satellite images to find intact humid forest, their ideal habitat. Habitat areas were quantified using ImageJ. The only sites found to be adequate for sustaining Harpy Eagle populations were the primary forests in the vicinities of Reserva Ecológica Mache Chindul and Reserva Ecológica Cotacachi Cayapas. The two reserves are expected to be …


The Current State Of Research On The Global Amphibian Epidemic, Chytridiomycosis: A Systematic Literature Review And View Into The Future Of The Field, Emily Dealto Apr 2020

The Current State Of Research On The Global Amphibian Epidemic, Chytridiomycosis: A Systematic Literature Review And View Into The Future Of The Field, Emily Dealto

Independent Study Project (ISP) Collection

Recent years have shown a rapid decline in global frog populations. Among other issues, one main cause of these declines has been linked to chytridiomycosis, a disease caused by the fungus Batrachochytrium dendrobatidis, or Bd. The discovery of this fungus is relatively recent in the field of herpetology, and thus there is much still unknown about the disease such as its distribution and what causes certain areas and species to be more susceptible to it. A systematic literature review was conducted to see where the state of the research is currently, in order to gain a better view of the …


Two (Or More) Viruses In One Bat: A Systematic Quantitative Literature Review Of Viral Coinfection In Bats, Eli J. Kaufman Apr 2020

Two (Or More) Viruses In One Bat: A Systematic Quantitative Literature Review Of Viral Coinfection In Bats, Eli J. Kaufman

Independent Study Project (ISP) Collection

Viral coinfection is an important topic in pathogen dynamics, and can increase viral shedding and change disease outcomes. As bats are carriers of important zoonoses, such as the SARS coronaviruses, rabies, and other deadly viruses, knowing more about their coinfection dynamics is important. This quantitative systematic literature review sought to show how many papers reported bat viral coinfections, and created three databases. The first database, the SQLR database was based on searches for coinfections. The second database, the Astrovirus database was to determine how much of the literature was being missed by examining a single viral family more in depth …


Olfactory Behavioral Responses Of Mosquito Vectors To Select Attractants And Floral Scents As Related To Circadian Rhythms And Photoperiod Regimes, Bernadette A. Ferraro Apr 2020

Olfactory Behavioral Responses Of Mosquito Vectors To Select Attractants And Floral Scents As Related To Circadian Rhythms And Photoperiod Regimes, Bernadette A. Ferraro

Biomedical Sciences Theses & Dissertations

This dissertation discusses mosquito behavioral activities involving circadian rhythms defined as insect sensitivity to select of chemical volatiles that vary throughout the 24-hour day. Circannual rhythms occur over seasons varying in photoperiod, defined as the seasonal cycle of light and darkness. These cycles can be endogenously controlled by circadian clocks. The impetus for this research was initiated when reading about the neglected temporal dimension in the context of insect chemical ecology, including insect olfaction. It was proposed that sensitivity to odors does not change in general, but specific sensitivities could vary according to time of day. Chemical scents emitted by …


Prey Selection By Birds Of Prey, Anisha Pokharel Apr 2020

Prey Selection By Birds Of Prey, Anisha Pokharel

School of Biological Sciences: Dissertations, Theses, and Student Research

Prey selection is key to determine predator prey interaction and understanding the complexity of food web structure. In this thesis, we used two different approaches to understanding prey selection by North American birds of prey. Using a conventional method, in Chapter 1 we compared pellet analysis and trapping data to assess patterns of prey selection of barn owls in western Nebraska. Microtus spp. comprised 55.8% of the prey items in the barn owl’s diet. The proportion of several prey types in the diet were significantly different from the expected proportion based on trapping. This pattern may indicate barn owls actively …


Evaluating Potential Effects Of 2019 Australian Bushfires On Animal Species, Protected Land, And Land Cover, Alyssa J. Kaewwilai Apr 2020

Evaluating Potential Effects Of 2019 Australian Bushfires On Animal Species, Protected Land, And Land Cover, Alyssa J. Kaewwilai

Student Publications

The 2019-2020 Australian bushfire event had exceptionally dry, hot conditions as well as high potential impacts on the country’s wildlife and natural resources. The purpose of the study was to analyze the potential impacts of the 2019 Australian bushfire event on animal species, protected land, and varied land cover types. The research question of this project is: how does the location of the Australian Bushfires of 2020 potentially impact animal species, protected land and national parks, as well as different land covers? Raster calculator was used to combine and classify layers from the MODIS Burned Area Product of burned (1) …


Comparison Of Comprehensive Health Score In North American Housed Giraffe And Free-Ranging Giraffe From South Africa, Haley Beer Apr 2020

Comparison Of Comprehensive Health Score In North American Housed Giraffe And Free-Ranging Giraffe From South Africa, Haley Beer

Department of Animal Science: Dissertations, Theses, and Student Research

Stress is evident in many animal species and has been correlated to disease prevalence. During stressful events, allostasis is initiated by physiologic systems to maintain or reestablish homeostasis to protect an organism’s viability. Over time, the acclimation to frequent stress causes systematic dysregulation, leading to the phenomena of increased allostatic load. Allostatic load has been assessed in animal species via serum through selection of representative, multi-system biomarker indices. Perception and number of stress events may impact dysregulation severity, yielding allostatic load as a predictive tool. However, the allostatic load methodology poses application limitations to individuals without historical data and those …


Evaluation Of Protein Sources And Holstein Finishing Systems For Organic Beef Production And A Comparison Of Single And Dual Implant Strategies In Finishing Heifers, Elizabeth A. Schumacher Apr 2020

Evaluation Of Protein Sources And Holstein Finishing Systems For Organic Beef Production And A Comparison Of Single And Dual Implant Strategies In Finishing Heifers, Elizabeth A. Schumacher

Department of Animal Science: Dissertations, Theses, and Student Research

Two in situ experiments were conducted to compare the rumen undegradable protein content (RUP) and RUP digestibility of conventional and organic field peas, fish meal, dehydrated alfalfa, and soybean meal. Significant differences were detected between feed samples in both studies for all variables measured. Variation existed between sample types but the data did not suggest that organic and conventional feeds are different when processed with the same methods. A performance experiment was conducted utilizing individually fed Holstein steers comparing the effect of RUP source in a simulated organic production system. Dietary treatments were: no supplemental protein (NONE), field peas (FP), …


The Effect Of Slow-Feeding Hay Nets On Post-Prandial Equine Salivary Cortisol Levels, Grace Simpson Apr 2020

The Effect Of Slow-Feeding Hay Nets On Post-Prandial Equine Salivary Cortisol Levels, Grace Simpson

Undergraduate Honors Thesis Projects

Throughout its evolution, the Equus caballus, or horse, developed a physiological response to environmental alterations involving the synthesis and release of cortisol from the hypothalamic-pituitary-adrenal axis, to regulate blood glucose levels, vascular tone and hormone release throughout the body (Ambrojo et al., 2018). With a hypothesis that changing a horse’s feeding method can alter salivary cortisol levels, the aim of this research project was to determine if feeding forage to horses in slow-feeding haynets would significantly reduce acute cortisol salivary level fluctuations, which would be valuable to minimize horses’ stress and increase overall welfare. Two feeding methods …


Exploring Song As A Reproductive Isolation Mechanism In A Hybridizing Population Of Winged Warblers, Amy E. Janik Apr 2020

Exploring Song As A Reproductive Isolation Mechanism In A Hybridizing Population Of Winged Warblers, Amy E. Janik

Masters Theses

Reproductive isolation mechanisms such as song are used by birds to promote assortative mating by species and prevent gene flow when closely related species come into secondary contact. Based on the strength of a reproductive barrier, signals in hybrid zones can diverge and become more dissimilar to maintain species or converge to become more similar and make species discrimination more difficult. When two closely related species overlap in territories and have similar songs, song convergence is likely and has the capacity to disrupt species recognition. We test the hypothesis that song acts as a reproductive isolation mechanism by examining song …


Performance Of Elite Maize Genotypes Under Selected Sustainable Intensification Options In Kenya, Leonard Rusinamhodzi, Dan Makumbi, James M. Njeru, Fred Kanampiu Apr 2020

Performance Of Elite Maize Genotypes Under Selected Sustainable Intensification Options In Kenya, Leonard Rusinamhodzi, Dan Makumbi, James M. Njeru, Fred Kanampiu

All Peer-Reviewed Publications

Combining different cropping and tillage systems with different genotypes across several cropping seasons can reveal opportunities for sustainable intensification (SI). The objective of this study was to assess the performance of six maize genotypes under intercropping with conservation tillage (no-till) – two promising options for SI. The experiment was carried out over three years (or six cropping seasons) at Kiboko Research Station, Kenya with sole cropping and mouldboard ploughing as baseline production systems. Results showed that maize genotypes and cropping systems had a significant effect on yield, but the effect of tillage was not significant. Moreover, there was no significant …


Functions Of Vocal Mimicry In The Complex Song Of The European Starling, Sturnus Vulgaris, Maria Goller Apr 2020

Functions Of Vocal Mimicry In The Complex Song Of The European Starling, Sturnus Vulgaris, Maria Goller

School of Biological Sciences: Dissertations, Theses, and Student Research

Vocal learning is an ability that has only evolved in a handful of taxa. Songbirds learn their songs, and some species have flexible learning in which they not only incorporate species-specific sounds, but heterospecific and/or environmental sounds as well. The functions of vocal mimicry are still unknown for many species and studying mimicry can teach us about the variation within the song learning process. In this thesis, I focused on five hypotheses on how mimicry could function in sexual selection. The repertoire size hypothesis suggests that selection for larger repertoire sizes allows mimicry to occur because imitation can increase repertoire …