Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 13 of 13

Full-Text Articles in Life Sciences

The Effect Of Testosterone On The Spring Migratory Phenotype Of A North American Songbird (Zonotrichia Albicollis), Caitlin L. Vandermeer Dec 2013

The Effect Of Testosterone On The Spring Migratory Phenotype Of A North American Songbird (Zonotrichia Albicollis), Caitlin L. Vandermeer

Electronic Thesis and Dissertation Repository

In passerines, the endocrine modulators responsible for seasonal changes in migratory behaviour and physiology are unclear. Spring photoperiods alter androgen levels, influencing muscle mass and fat deposition rates to power migration, as well as enhance nocturnal migratory restlessness activity (Zugunruhe). My study compared physiological indicators and migratory restlessness in castrated and intact white-throated sparrows (Zonotrichia albicollis) following photoperiod and hormone manipulation. Nocturnal restlessness activity was highest in migratory intact males or migratory castrated males that received testosterone replacement. Liver mass decreased in all photostimulated migratory groups regardless of testosterone treatment. Likewise, oxidative enzyme activity was unrelated to testosterone, …


Colour And Odour Drive Fruit Selection And Seed Dispersal By Mouse Lemurs, Kim Valenta, Ryan J. Burke, Sarah A. Styler, Derek A. Jackson, Amanda D. Melin, Shawn M. Lehman Aug 2013

Colour And Odour Drive Fruit Selection And Seed Dispersal By Mouse Lemurs, Kim Valenta, Ryan J. Burke, Sarah A. Styler, Derek A. Jackson, Amanda D. Melin, Shawn M. Lehman

Dartmouth Scholarship

Animals and fruiting plants are involved in a complex set of interactions, with animals relying on fruiting trees as food resources, and fruiting trees relying on animals for seed dispersal. This interdependence shapes fruit signals such as colour and odour, to increase fruit detectability, and animal sensory systems, such as colour vision and olfaction to facilitate food identification and selection. Despite the ecological and evolutionary importance of plant-animal interactions for shaping animal sensory adaptations and plant characteristics, the details of the relationship are poorly understood. Here we examine the role of fruit chromaticity, luminance and odour on seed dispersal by …


From Gibbons To Gymnasts: A Look At The Biomechanics And Neurophysiology Of Brachiation In Gibbons And Its Human Rediscovery, Emma Et Pennock May 2013

From Gibbons To Gymnasts: A Look At The Biomechanics And Neurophysiology Of Brachiation In Gibbons And Its Human Rediscovery, Emma Et Pennock

Student Works

This conference paper serves to examine the evolutionary linkages of a brachiating ancestor in humans, the biomechanical and neurophysiology of modern day brachiators, and the human rediscovery of this form of locomotion. Brachiation is arguably one of the most metabolically effective modes of travel by any organism and can be observed most meritoriously in Gibbons. The purpose of the research conducted for this paper was to encourage further exploration of the neurophysiological similarities and differences between humans and non-human primates. The hope is that in spurring more interest and research in this area, further possibilities for rehabilitating brain injury will …


Effects Of Leaflet Orientation And Root Morphology On Physiological Traits And Yield In Soybeans., Richard Dewayne Johnson May 2013

Effects Of Leaflet Orientation And Root Morphology On Physiological Traits And Yield In Soybeans., Richard Dewayne Johnson

Doctoral Dissertations

Drought is the most important abiotic stress adversely affecting soybean (Glycine max (L.) Merr.) yield. Leaflet orientation has been shown to reduce leaflet temperatures and transpiration while root morphology has been related to slower wilting phenotypes. The objective of this study was to investigate effects of leaflet orientation and rooting morphology on whole plant transpiration, yield, water use efficiency, and other physiological traits in soybeans using grafting techniques, population lines, near-isogenic lines, and restrained leaf canopy experiments. Experiments were conducted in Knoxville, TN with additional yield trial plots at Springfield, Spring Hill, and Milan, TN. Data were collected on …


A Comparative Genomics Approach To Using High-Throughput Gene Expression Data To Study Limb Regeneration In Ambystoma Mexicanum And Danio Rerio: Developing A More Completely Annotated Database, Justin Bolinger May 2013

A Comparative Genomics Approach To Using High-Throughput Gene Expression Data To Study Limb Regeneration In Ambystoma Mexicanum And Danio Rerio: Developing A More Completely Annotated Database, Justin Bolinger

Honors College

Axolotl (Ambystoma mexicanum) and the zebrafish (Danio rerio) represent organisms extensively studied because of their remarkable capability of fully regenerating completely functional tissues after a traumatic event takes place. However, the research conducted with regards to the genomics of these two organisms has remained fairly independent of each other. The intent of this study is to bridge this gap and connect genes between axolotl and the zebrafish by use a “Rosetta stone” framework to develop a database comparing gene expression data obtained from both microarraybased experiments and high-throughput DNA sequencing of axolotl and zebrafish mRNA and miRNA. Using gene data …


The Sub-Lethal Effects Of Repeated Cold Exposure In Insects, Katie Elizabeth Marshall Apr 2013

The Sub-Lethal Effects Of Repeated Cold Exposure In Insects, Katie Elizabeth Marshall

Electronic Thesis and Dissertation Repository

While insect cold tolerance has been well studied, the vast majority of work has focused on the effects of a single cold exposure. However, many abiotic environmental stresses, including temperature, fluctuate within an organism's lifespan. In this thesis I address two major questions. First, does frequency of cold exposure impose additional stress on insects? Second, how does this stress translate to performance and fitness? I first summarize the literature on the effects of repeated cold exposure in insects, critically examining experimental designs. I then address my questions experimentally using four insect species with contrasting life histories and responses to cold …


Euryhalinity In An Evolutionary Context, Eric T. Schultz, Stephen D. Mccormick Jan 2013

Euryhalinity In An Evolutionary Context, Eric T. Schultz, Stephen D. Mccormick

EEB Articles

This chapter focuses on the evolutionary importance and taxonomic distribution of euryhalinity. Euryhalinity refers to broad halotolerance and broad halohabitat distribution. Salinity exposure experiments have demonstrated that species vary tenfold in their range of tolerable salinity levels, primarily because of differences in upper limits. Halotolerance breadth varies with the species’ evolutionary history, as represented by its ordinal classification, and with the species’ halohabitat. Freshwater and seawater species tolerate brackish water; their empirically-determined fundamental haloniche is broader than their realized haloniche, as revealed by the halohabitats they occupy. With respect to halohabitat distribution, a minority of species (<10%) are euryhaline. Habitat-euryhalinity is prevalent among basal actinopterygian fishes, is largely absent from orders arising from intermediate nodes, and reappears in the most derived taxa. There is pronounced family-level variability in the tendency to be halohabitat-euryhaline, which may have arisen during a burst of diversification following the Cretaceous-Palaeogene extinction. Low prevalence notwithstanding, euryhaline species are potent sources of evolutionary diversity. Euryhalinity is regarded as a key innovation trait whose evolution enables exploitation of new adaptive zone, triggering cladogenesis. We review phylogenetically-informed studies that demonstrate freshwater species diversifying from euryhaline ancestors through processes such as landlocking. These studies indicate that some euryhaline taxa are particularly susceptible to changes in halohabitat and subsequent diversification, and some geographic regions have been hotspots for transitions to freshwater. Comparative studies on mechanisms among multiple taxa and at multiple levels of biological integration are needed to clarify evolutionary pathways to, and from, euryhalinity.


Knockdown Of Vitellogenin By Rnai Increases Survivorship But Exhibits Similar Physiological Responses To Ovariectomy In Grasshoppers, Alicia G. Linquist Jan 2013

Knockdown Of Vitellogenin By Rnai Increases Survivorship But Exhibits Similar Physiological Responses To Ovariectomy In Grasshoppers, Alicia G. Linquist

UNF Graduate Theses and Dissertations

Reduced reproduction has been shown to increase lifespan in many animals, yet the mechanisms behind this trade-off are mostly unknown. A previous study has shown that in the lubber grasshopper, Romalea microptera, ovariectomized (OVX) individuals have a 30% increase in lifespan relative to controls (Sham). In a separate study, an increase in fat body mass and a halting of ovarian growth were seen upon reduction of vitellogenin transcript via RNAi (VgRNAi). These data suggest that VgRNAi increases lifespan through the trade-off between reproduction and longevity and animals with combined ovariectomy and VgRNAi, might show additive physiological responses. In this …


Comparative Sugar Transport By Crustacean Hepatopancreas And Intestine, Ada Duka Jan 2013

Comparative Sugar Transport By Crustacean Hepatopancreas And Intestine, Ada Duka

UNF Graduate Theses and Dissertations

Glucose is transported in crustacean hepatopancreas and intestine by Na+-dependent co-transport, while Na+-dependent D-fructose influx has only been described for the hepatopancreas. It is still unclear if the two sugars are independently transported by two distinct cotransporter carrier systems. In this study lobster (Homarus americanus) hepatopancreas brush border membrane vesicles (BBMV) were used to characterize, in detail, the cation-dependency of both D-[3H] glucose and D-[3H] fructose influxes, while in vitro perfused intestines were employed to determine the nature of cation-dependent sugar transport in this organ. Over the sodium concentration range …


Variable Levels Of Atmospheric Oxygen Do Not Affect Microanatomy And Limb Bone Geometry In Alligator Mississippiensis, Susan Lee Lujan Jan 2013

Variable Levels Of Atmospheric Oxygen Do Not Affect Microanatomy And Limb Bone Geometry In Alligator Mississippiensis, Susan Lee Lujan

Theses Digitization Project

Striking changes in atmospheric oxygen levels have occured since the beginning of the Phanerozic 542 million years ago. Alligators belong to a clade of vertebrates with a long evolutionary history spanning much of this variability in atmospheric oxygen. An investigation into the effects of hypoxia and hyperoxia on skeletal growth and physiology in alligators may help to reconstruct the life history of archosaurs, explain patterns in the fossil record, and broaden our understanding of the processes underlying long term success of this clade.


Population Genetics And Ecology Of Regional Malaria Vectors In Amazonian Brazil, Sascha Naomi Mckeon Jan 2013

Population Genetics And Ecology Of Regional Malaria Vectors In Amazonian Brazil, Sascha Naomi Mckeon

Legacy Theses & Dissertations (2009 - 2024)

Species complexes are common among anopheline mosquitoes, but only some members of complexes are disease vectors. Research involving overall patterns of divergence, phylogenetic relationships and population structure is partly driven by the operational need to be able to reliably distinguish component taxa that may be involved in malaria transmission. Anopheles triannulatus, An. nuneztovari and An. albitarsis are broadly distributed species complexes that contain local and regionally important malaria vectors, whose genetic diversity has been largely overshadowed by studies involving An. darlingi, the principal vector of Central and South America. I have analyzed the ecological suitability of habitats and geographical ranges …


Postcranial Description And Reconstruction Of The Varanodontine Varanopid Aerosaurus Wellesi (Synapsida: Eupelycosauria), Valerie Ann Pelletier Jan 2013

Postcranial Description And Reconstruction Of The Varanodontine Varanopid Aerosaurus Wellesi (Synapsida: Eupelycosauria), Valerie Ann Pelletier

Theses Digitization Project

The postcranial skeleton of the varanopid synapsid aerosaurus wellesi is reconstructed based on several specimens including partly articulated material of an apparently fully adult specimen. Comparisons are made with other known varanopid taxa, reaffirming its position as a basal varanondontine.


Mechanisms Of Nitrogenous Waste Excretion During The Complex Life Cycle Of The Sea Lamprey (Petromyzon Marinus), James M. Neal Mr. Jan 2013

Mechanisms Of Nitrogenous Waste Excretion During The Complex Life Cycle Of The Sea Lamprey (Petromyzon Marinus), James M. Neal Mr.

Theses and Dissertations (Comprehensive)

Sea lampreys (Petromyzon marinus) are a phylogenetically ancient jawless fish, with a multi-staged life cycle characterized by a prolonged suspension-feeding larval stage, which is followed by metamorphosis into parasitic lampreys that feed on the protein-rich blood of fishes. The switch from a nutrient poor to protein-rich diet in the sea lamprey is associated with an increased capacity to deaminate excess amino acids and to excrete ammonia and urea following metamorphosis. The focus of this thesis was to determine if changes in nitrogenous waste transporter protein abundance facilitate ammonia and urea excretion during different stages of the sea lamprey …