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

Digital Commons Network™

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

Biology

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 33421 - 33450 of 39341

Full-Text Articles in Entire DC Network

Regional Variation In Recruitment Of Hemlock Seedlings And Saplings In The Upper Great Lakes, Usa, Thomas P. Rooney, Ronald J. Mccormick, Stephen L. Solheim, Donald M. Waller Aug 2000

Regional Variation In Recruitment Of Hemlock Seedlings And Saplings In The Upper Great Lakes, Usa, Thomas P. Rooney, Ronald J. Mccormick, Stephen L. Solheim, Donald M. Waller

Biological Sciences Faculty Publications

Mature eastern hemlock–northern hardwood forest cover decreased drastically in the upper Midwest following European settlement and has yet to rebound substantially. Previous studies show that stands retaining substantial hemlock canopy coverage have low hemlock seedling and sapling densities. Results from various geographically restricted studies suggest several possible mechanisms that could cause low seedling or sapling density. We examined the relative importance of these proposed mechanisms in the Southern Superior Uplands Section of the Laurentian Forest Province. We surveyed 294- m2 plots in 100 hemlock stands in northern Wisconsin and western upper Michigan to assess how these proposed mechanisms affect the …

Go to article

The Role Of Nf-Кb Activation In Breast Carcinoma And Glioblastoma Cell Lines, Kelly T. Murphy Aug 2000

The Role Of Nf-Кb Activation In Breast Carcinoma And Glioblastoma Cell Lines, Kelly T. Murphy

Masters Theses

The nuclear factor-КB (NF-КB)/Rel family of inducible dimeric transcription factors regulates numerous genes associated with the immune, mitogenic, and apoptotic responses. Investigations were made into the role of NF-КB in breast carcinoma (MCF-7, T47D, MDA-MB-231) and glioblastoma (U87MG, U373MG, Ul 18MG) cell lines. NF-КB binding to DNA was quantified using both gel mobility shift assays and transient transfections of a vector containing a luciferase gene under the control of 4 tandem copies of the NF-КB binding sequence. To determine the correlation between NF-КB activation, cellular proliferation, and foci formation, the tumor cells were cultured and analyzed in the presence of …

Go to article

Isolation And Characterization Of A Genetic Locus That Confers Tolerance To Cadmium And Zinc In Pseudomonas Fluorescens, Szi Fei Feng Aug 2000

Isolation And Characterization Of A Genetic Locus That Confers Tolerance To Cadmium And Zinc In Pseudomonas Fluorescens, Szi Fei Feng

Masters Theses

This thesis describes the isolation and characterization of a region containing several genes involved in metal tolerance in the common soil bacterium, Pseudomonas fluorescens ATCC 13525. The DNA region was identified in a cadmium and zinc sensitive mutant, 45-B10, which contains a lacZ-based reporter gene transposon Tn5-B20 inserted in the chromosome. The DNA surrounding the transposon was cloned from this mutant strain and DNA sequencing of this region revealed seven genes that share similarity with genes whose products are involved in the cation-proton antiporter efflux system of other Gram-negative bacteria. Complete DNA sequence was obtained from four of these …

Go to article

Aintegumenta Promotes Petal Identity And Acts As A Negative Regulator Of Agamous, Beth A. Krizek, Valerie Prost, Anthony Macias Aug 2000

Aintegumenta Promotes Petal Identity And Acts As A Negative Regulator Of Agamous, Beth A. Krizek, Valerie Prost, Anthony Macias

Faculty Publications

The Arabidopsis AINTEGUMENTA (ANT) gene has been shown previously to be involved in ovule development and in the initiation and growth of floral organs. Here, we show that ANT acts in additional processes during flower development, including repression of AGAMOUS (AG) in second whorl cells, promotion of petal epidermal cell identity, and gynoecium development. Analyses of ap2-1 ant-6 double mutants reveal that ANT acts redundantly with AP2 to repress AG in second whorl cells. The abaxial surface of ant petals contains features such as stomata and elongated, interdigitated cells that are not present on wild-type petals. …

Go to article

The Impact Of Lianas On Tree Regeneration In Tropical Forest Canopy Gaps: Evidence For An Alternative Pathway Of Gap‐Phase Regeneration, Stefan A. Schnitzer, James W. Dalling, Walter P. Carson Aug 2000

The Impact Of Lianas On Tree Regeneration In Tropical Forest Canopy Gaps: Evidence For An Alternative Pathway Of Gap‐Phase Regeneration, Stefan A. Schnitzer, James W. Dalling, Walter P. Carson

Biological Sciences Faculty Research and Publications

1 Regeneration in forest canopy gaps is thought to lead invariably to the rapid recruitment and growth of trees and the redevelopment of the canopy. Our observations, however, suggest that an alternate successional pathway is also likely, whereby gap‐phase regeneration is dominated by lianas and stalled in a low‐canopy state for many years. We investigated gap‐phase regeneration in an old‐growth tropical forest on Barro Colorado Island (BCI) in Panama to test the following two hypotheses: (i) many gaps follow a pathway in which they remain at a low canopy height and are dominated by lianas and (ii) the paucity of …

Go to article

Chromatin Organization And Transcriptional Control Of Gene Expression In Drosophila, G Farkas, B Leibovitch, Sarah C.R. Elgin Aug 2000

Chromatin Organization And Transcriptional Control Of Gene Expression In Drosophila, G Farkas, B Leibovitch, Sarah C.R. Elgin

Biology Faculty Research

It is increasingly clear that the packaging of DNA in nucleosome arrays serves not only to constrain the genome within the nucleus, but also to encode information concerning the activity state of the gene. Packaging limits the accessibility of many regulatory DNA sequence elements and is functionally significant in the control of transcription, replication, repair and recombination. Here, we review studies of the heat-shock genes, illustrating the formation of a specific nucleosome array at an activatable promoter, and describe present information on the roles of DNA-binding factors and energy-dependent chromatin remodeling machines in facilitating assembly of an appropriate structure. Epigenetic …

Go to article

Physiology Of A Microgravity Environment Invited Review: Microgravity And Skeletal Muscle, Robert H. Fitts, Danny R. Riley, Jeffrey J. Widrick Aug 2000

Physiology Of A Microgravity Environment Invited Review: Microgravity And Skeletal Muscle, Robert H. Fitts, Danny R. Riley, Jeffrey J. Widrick

Biological Sciences Faculty Research and Publications

Spaceflight (SF) has been shown to cause skeletal muscle atrophy; a loss in force and power; and, in the first few weeks, a preferential atrophy of extensors over flexors. The atrophy primarily results from a reduced protein synthesis that is likely triggered by the removal of the antigravity load. Contractile proteins are lost out of proportion to other cellular proteins, and the actin thin filament is lost disproportionately to the myosin thick filament. The decline in contractile protein explains the decrease in force per cross-sectional area, whereas the thin-filament loss may explain the observed postflight increase in the maximal velocity …

Go to article

Uncharged Trna Activates Gcn2 By Displacing The Protein Kinase Moiety From A Bipartite Trna-Binding Domain, Jinsheng Dong, Hongfang Qiu, Minerva Garcia-Barrio, James T. Anderson, Alan G. Hinnebusch Aug 2000

Uncharged Trna Activates Gcn2 By Displacing The Protein Kinase Moiety From A Bipartite Trna-Binding Domain, Jinsheng Dong, Hongfang Qiu, Minerva Garcia-Barrio, James T. Anderson, Alan G. Hinnebusch

Biological Sciences Faculty Research and Publications

Protein kinase GCN2 regulates translation in amino acid–starved cells by phosphorylating eIF2. GCN2 contains a regulatory domain related to histidyl-tRNA synthetase (HisRS) postulated to bind multiple deacylated tRNAs as a general sensor of starvation. In accordance with this model, GCN2 bound several deacylated tRNAs with similar affinities, and aminoacylation of tRNAPhe weakened its interaction with GCN2. Unexpectedly, the C-terminal ribosome binding segment of GCN2 (C-term) was required in addition to the HisRS domain for strong tRNA binding. A combined HisRS+C-term segment bound to the isolated protein kinase (PK) domain in vitro, and tRNA impeded this interaction. An activating mutation …

Go to article

High Efficiency Separation Of Microbial Aggregates Using Capillary Electrophoresis, J. M. Schneiderheinze, Daniel W. Armstrong, G. Schulte, David J. Westenberg Aug 2000

High Efficiency Separation Of Microbial Aggregates Using Capillary Electrophoresis, J. M. Schneiderheinze, Daniel W. Armstrong, G. Schulte, David J. Westenberg

Chemistry Faculty Research & Creative Works

Recent advances in the technique of capillary electrophoresis have demonstrated fast, highly efficient separation of mixtures of intact microbes. This paper describes the application of this technique for the separation of microbial aggregates of Micrococcus luteus, Saccharomyces cerevisiae, or Alcaligenes faecalis. The aggregates of these microbes were resolved into several highly efficient peaks with analysis times under 10 min and efficiencies approaching 1 000 000 plates m-1 in some cases. A reproducible relationship was found between the electrophoretic mobility and the aggregation number or size of the cluster under a given set of experimental conditions. Often, cellular aggregation was reversible …

Go to article

Early Instar Growth And Survivorship In The Common Baskettail Dragonfly Epitheca Cynosura (Anisoptera: Corduliidae)., Bryan Arthur Reece Aug 2000

Early Instar Growth And Survivorship In The Common Baskettail Dragonfly Epitheca Cynosura (Anisoptera: Corduliidae)., Bryan Arthur Reece

Electronic Theses and Dissertations

Egg masses of Epitheca cynosura were collected from Bays Mountain Park, Tennessee, USA, in June, 1999. Newly hatched individuals were placed into enclosures and sampled at scheduled time intervals throughout the summer. Enclosures were exposed to combinations of high and low densities and presence/absence of a second-year class E. cynosura predator. Survivorship, mean head widths, and mean dry masses were compared across treatments. Due to poor recovery of early-instar larvae, survivorship showed no significant differences in mortality among treatments. The predator present treatment caused significantly smaller head widths and dry masses only on days 42 and 55. The density treatment …

Go to article

Physiology Of A Microgravity Environment Invited Review: Microgravity And Skeletal Muscle, Robert H. Fitts, Danny R. Riley, Jeffrey J. Widrick Aug 2000

Physiology Of A Microgravity Environment Invited Review: Microgravity And Skeletal Muscle, Robert H. Fitts, Danny R. Riley, Jeffrey J. Widrick

Biological Sciences Faculty Research and Publications

Spaceflight (SF) has been shown to cause skeletal muscle atrophy; a loss in force and power; and, in the first few weeks, a preferential atrophy of extensors over flexors. The atrophy primarily results from a reduced protein synthesis that is likely triggered by the removal of the antigravity load. Contractile proteins are lost out of proportion to other cellular proteins, and the actin thin filament is lost disproportionately to the myosin thick filament. The decline in contractile protein explains the decrease in force per cross-sectional area, whereas the thin-filament loss may explain the observed postflight increase in the maximal velocity …

Go to article

Kentucky Salamanders Of The Genus Desmognathus: Their Identification, Distribution, And Morphometric Variation, Leslie Scott Meade Jul 2000

Kentucky Salamanders Of The Genus Desmognathus: Their Identification, Distribution, And Morphometric Variation, Leslie Scott Meade

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Science and Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science in Biology by Leslie Scott Meade on July 24, 2000.

Go to article

Direct Determination Of The Kinetics Of Oxygen Diffusion To The Photocytes Of A Bioluminescent Elaterid Larva, Measurement Of Gas- And Aqueous-Phase Diffusional Barriers And Modelling Of Oxygen Supply, G. S. Timmins, E. J. Bechara, H. M. Swartz Jul 2000

Direct Determination Of The Kinetics Of Oxygen Diffusion To The Photocytes Of A Bioluminescent Elaterid Larva, Measurement Of Gas- And Aqueous-Phase Diffusional Barriers And Modelling Of Oxygen Supply, G. S. Timmins, E. J. Bechara, H. M. Swartz

Dartmouth Scholarship

We describe the development and use of a direct kinetic technique to determine the time taken for oxygen to diffuse from the external environment into the light-producing cells (photocytes) in the prothorax of bioluminescent larvae of Pyrearinus termitilluminans. This was achieved by measuring the time course of the pseudoflash induced through sequential anoxia followed by normoxia. We have also determined the separate times taken for this oxygen diffusion in gaseous and tissue (predominantly aqueous) phases by using helium and nitrogen as the carrier gas. Of the total time taken for diffusion, that in the gas phase required 613+/-136 ms (mean …

Go to article

Molecular Aspect Of Leaf Senescence, Edward Himelblau, Betania Quirino, Yoo-Sun Noh, Richard Amasino Jul 2000

Molecular Aspect Of Leaf Senescence, Edward Himelblau, Betania Quirino, Yoo-Sun Noh, Richard Amasino

Biological Sciences

Senescence is the last stage of leaf development and one type of programmed cell death that occurs in plants. The relationships among senescence programs that are induced by a variety of factors have been addressed at a molecular level in recent studies. Furthermore, an overlap between the pathogen-response and senescence programs is beginning to be characterized. The complexity of the senescence program is also evident in studies of senescence-specific gene regulation and the role of photosynthesis and plant hormones in senescence regulation. New molecular-genetic approaches are expected to be useful in unraveling the molecular mechanisms of the leaf senescence program.

Go to article

Sequence Analysis Of Bacterial Dna In The Colon And Stomach Of The Tyrolean Iceman, Raul J. Cano, Friedrich Tiefenbrunner, Massimo Ubaldi, Clarissa Del Cueto, Stefania Luciani, Tobe Cox, Paula Orkand, Karl H. Kunzel, Franco Rollo Jul 2000

Sequence Analysis Of Bacterial Dna In The Colon And Stomach Of The Tyrolean Iceman, Raul J. Cano, Friedrich Tiefenbrunner, Massimo Ubaldi, Clarissa Del Cueto, Stefania Luciani, Tobe Cox, Paula Orkand, Karl H. Kunzel, Franco Rollo

Biological Sciences

The male human body found in an Alpine glacier on September 19, 1991 ("Tyrolean Iceman") has, for the first time in history, given scientists a chance to perform detailed anatomical, histological, and molecular investigations on the organs of a person from the Neolithic Age (5350-5100 B.P.). In the present study, tissue samples aseptically taken from the stomach and the colon of the mummy were utilized for DNA extraction, and the DNA was PCR-amplified, using primer pairs designed to bind to fragments of the 16s ribosomal RNA gene (16s rDNA) of a broad range of bacteria. The PCR products were cloned …

Go to article

Replicability And Recurrence In The Experimental Evolution Of A Group I Ribozyme, Martin M. Hanczyc, Robert L. Dorit Jul 2000

Replicability And Recurrence In The Experimental Evolution Of A Group I Ribozyme, Martin M. Hanczyc, Robert L. Dorit

Biological Sciences: Faculty Publications

In order to explore the variety of possible responses available to a ribozyme population evolving a novel phenotype, five Tetrahymena thermophila group I intron ribozyme pools were evolved in parallel for cleavage of a DNA oligonucleotide. These ribozyme populations were propagated under identical conditions and characterized when they reached apparent phenotypic plateaus; the populations that reached the highest plateau showed a near 100-fold improvement in DNA cleavage activity. A detailed characterization of the evolved response in these populations reveals at least two distinct phenotypic trajectories emerging as a result of the imposed selection. Not only do these distinct solutions exhibit …

Go to article

Energetics Of Larval Swimming And Metamorphosis In Four Species Of Bugula (Bryozoa), Dean E. Wendt Jun 2000

Energetics Of Larval Swimming And Metamorphosis In Four Species Of Bugula (Bryozoa), Dean E. Wendt

Biological Sciences

The amount of energy available to larvae during swimming, location of a suitable recruitment site, and metamorphosis influences the length of time they can spend in the plankton. Energetic parameters such as swimming speed, oxygen consumption during swimming and metamorphosis, and elemental carbon and nitrogen content were measured for larvae of four species of bryozoans, Bugula neritina, B. simplex, B. stolonifera, and B. turrita. The larvae of these species are aplanktotrophic with a short free-swimming phase ranging from less than one hour to a maximum of about 36 hours. There is about a fivefold difference in larval volume …

Go to article

Delivering Copper Within Plant Cells, Edward Himelblau, Richard M. Amasino Jun 2000

Delivering Copper Within Plant Cells, Edward Himelblau, Richard M. Amasino

Biological Sciences

Two genes recently identified in Arabidopsis thaliana may be involved in sequestering free copper ions in the cytoplasm and delivering copper to post-Golgi vesicles. The genes COPPER CHAPERONE and RESPONSIVE TO ANTAGONIST1 are homologous to copper-trafficking genes from yeast and humans. This plant copper-delivery pathway is required to create functional ethylene receptors. The pathway may also facilitate the transport of copper from senescing leaf tissue. In addition, several other genes have been identified recently that may have a role in copper salvage during senescence.

Go to article

A Biochemical Mechanism For Nonrandom Mutations And Evolution, Barbara E. Wright Jun 2000

A Biochemical Mechanism For Nonrandom Mutations And Evolution, Barbara E. Wright

Biological Sciences Faculty Publications

No abstract provided.

Go to article

An Est-Enriched Comparative Map Of Brassica Oleracea And Arabidopsis Thaliana, Tien-Hung Lan, Terrye A. Delmonte, Kim P. Reischmann, Joel Hyman, Stanley P. Kowalski, Jim Mcferson, Stephen Kresovich, Andrew H. Paterson Jun 2000

An Est-Enriched Comparative Map Of Brassica Oleracea And Arabidopsis Thaliana, Tien-Hung Lan, Terrye A. Delmonte, Kim P. Reischmann, Joel Hyman, Stanley P. Kowalski, Jim Mcferson, Stephen Kresovich, Andrew H. Paterson

Faculty Publications

A detailed comparative map of Brassica oleracea and Arabidopsis thaliana has been established based largely on mapping of Arabidopsis ESTs in two Arabidopsis and four Brassica populations. Based on conservative criteria for inferring synteny, “one to one correspondence” between Brassica and Arabidopsis chromosomes accounted for 57% of comparative loci. Based on 186 corresponding loci detected in B. oleracea and A. thaliana, at least 19 chromosome structural rearrangements differentiate B. oleracea and A. thaliana orthologs. Chromosomal duplication in the B. oleracea genome was strongly suggested by parallel arrangements of duplicated loci on different chromosomes, which accounted for 41% of loci …

Go to article

The Mayfly Newsletter, Peter M. Grant Jun 2000

The Mayfly Newsletter, Peter M. Grant

The Mayfly Newsletter

The Mayfly Newsletter is the official newsletter of the Permanent Committee of the International Conferences on Ephemeroptera.

Go to article

Reflections On Scientific And Religious Metaphor, Ursula Goodenough Jun 2000

Reflections On Scientific And Religious Metaphor, Ursula Goodenough

Biology Faculty Research

The importance of scientific conflicts for theology and philosophy is difficult to judge. In many disputes of significance, prominent scientists can be found on both sides. Profound philosophical and religious implications are sometimes said to be implied by the new theory as well. This article examines the dispute over natural selection between Richard Dawkins and Stephen Jay Gould as a contemporary instance of such a conflict. While both claim that profound philosophical conclusions flow from their own alternative account of evolution, I suggest that the implication is not as great as is claimed and that the alleged implications have as …

Go to article

Effects Of Elevated Carbon Dioxide And Nitrogen Fixation On A Legume-Based System: A Test With Soybean And The Soybean Looper, Pseudoplusia Includens, Angela M. Spickard Jun 2000

Effects Of Elevated Carbon Dioxide And Nitrogen Fixation On A Legume-Based System: A Test With Soybean And The Soybean Looper, Pseudoplusia Includens, Angela M. Spickard

Masters Theses

Wild-type and non-nodulated soybean were grown at 367 ± 10 ppm [ambient] and 756 ± 10 ppm [elevated] CO2 to determine whether nitrogen fixation could minimize the effects of elevated CO2 on plant nutritional and defensive chemistry. Relative to non-nodulated soybean, wild-type soybean had higher concentrations of leaf nitrogen and proteinase inhibitors, as well as lower C:N ratios and lower phenolics. Elevated CO2 resulted in decreased leaf nitrogen and proteinase inhibitor contents, and increased C:N ratios and phenolics in both soybean strains. Constitutive levels of phenolics and proteinase inhibitors occurred as predicted by the Carbon/Nutrient Balance hypothesis …

Go to article

The Occurrence Of The Freshwater Clams, Musculium Partumeium (Say) And Pisidium Casertanum (Poli) (Bivalvia: Sphaeriidae), In The Hawaiian Islands, Albert J. Burky, Carl M. Way, Skippy Hau, M. Eric Benbow Jun 2000

The Occurrence Of The Freshwater Clams, Musculium Partumeium (Say) And Pisidium Casertanum (Poli) (Bivalvia: Sphaeriidae), In The Hawaiian Islands, Albert J. Burky, Carl M. Way, Skippy Hau, M. Eric Benbow

Biology Faculty Publications

Sphaeriid clams were collected from an ancient, continuously cultivated taro pond complex at Ke‘anae Peninsula, Maui. Both species are known for adaptations for temporary pond habitats and could have been initially introduced by the earliest Hawaiian settlers transported with moist taro root stock from other areas of Oceania.

Go to article

Expression Of Smooth Muscle Myosin Light Chain 17 And Unloaded Shortening In Single Smooth Muscle Cells, Thomas J. Eddinger, A. A. Korwek, Daniel P. Meer, Jennifer J. Sherwood Jun 2000

Expression Of Smooth Muscle Myosin Light Chain 17 And Unloaded Shortening In Single Smooth Muscle Cells, Thomas J. Eddinger, A. A. Korwek, Daniel P. Meer, Jennifer J. Sherwood

Biological Sciences Faculty Research and Publications

These experiments were performed to test the hypotheses that myosin light chain 17 (MLC17) a and b isoform expression varies between individual vascular smooth muscle (SM) cells and that their expression correlates with cell unloaded shortening velocity. Single SM cells isolated from rabbit aorta and carotid arteries were used to measure unloaded shortening velocity and subsequently were analyzed via RT-PCR for MLC17 a and b mRNA ratio. The MLC17b/a mRNA and protein ratios from adjacent tissue sections correlate very well (R2 = 0.68), allowing use of the mRNA ratio to predict the protein ratio. …

Go to article

Identification Of Human Rap1: Implications For Telomere Evolution, Bibo Li, Stephanie Oestreich, Titia De Lange May 2000

Identification Of Human Rap1: Implications For Telomere Evolution, Bibo Li, Stephanie Oestreich, Titia De Lange

Biological, Geological, and Environmental Faculty Publications

It has been puzzling that mammalian telomeric proteins, including TRF1, TRF2, tankyrase, and TIN2 have no recognized orthologs in budding yeast. Here, we describe a human protein, hRap1, that is an ortholog of the yeast telomeric protein, scRap1p. hRap1 has three conserved sequence motifs in common with scRap1, is located at telomeres, and affects telomere length. However, while scRap1 binds telomeric DNA directly, hRap1 is recruited to telomeres by TRF2. Extending the comparison of telomeric proteins to fission yeast, we identify S. pombe Taz1 as a TRF ortholog, indicating that TRFs are conserved at eukaryotic telomeres. The data suggest that …

Go to article

Protozoan Free Colonies Of Lepidoptera, Kingston L. H. Leong May 2000

Protozoan Free Colonies Of Lepidoptera, Kingston L. H. Leong

Biological Sciences

A method for the establishment and maintenance of colonies of Lepidoptera which are free of contamination with protozoa is provided. The colonies consists of individuals capable of breeding and producing viable, noncontaminated butterflies.

Go to article

Sickle Cell Disease: Animal Models And Gene Therapy, Francesca M. Mellion May 2000

Sickle Cell Disease: Animal Models And Gene Therapy, Francesca M. Mellion

Electronic Dissertations and Theses

Sickle cell disease is a worldwide health problem in countries ranging from its origin, Africa, to the United States of America. The understanding of sickle cell disease dates to Zimbabwe in the 1940's. Sickle cell trait is the term used to describe healthy unaffected carriers (heterozygous) of the genetic condition known as Sickle Cell Disease. It is estimated that there are about 100,000 genes in the human body and each of them codes for a different trait. About 5,000 of these genes are known to carry mutations serious enough to cause genetic diseases. This research deal with sickle cell mice …

Go to article

Effects Of Forced Weaning On Mother-Daughter Associations And Reproduction In Bison (Bos Bison), Jennifer S. Brookshier May 2000

Effects Of Forced Weaning On Mother-Daughter Associations And Reproduction In Bison (Bos Bison), Jennifer S. Brookshier

Biology

While the social organization of ungulates has received much attention, the nature and extent of the mother-daughter association is still not fully known for some species. In bison, mothers and daughters have a long-term association that may extend beyond the age of weaning. This association is believed to facilitate the daughters' social integration into the herd. I compared the mother-daughter association for 29 yearling females that were forcibly weaned from their mothers to that of 19 yearling females that were naturally weaned. Forcibly weaned yearlings did not reassociate with their mothers following winter separation, while naturally weaned yearlings associated with …

Go to article

Sexual Dichromatism In Bohemian Waxwings, James Brian Burns May 2000

Sexual Dichromatism In Bohemian Waxwings, James Brian Burns

Biology

If a species of birds is monomorphic, how do individuals identify members of the opposite sex? Birds may use cues in the ultraviolet wavelengths (350-400 nm), which are invisible to humans. This thesis presents evidence of sexual dichromatism in Bohemian Waxwings (Bombycilla garrulus). The strongest differences occurred in the tail coverts, the yellow tail tips, and the red waxy tips of the secondaries. Like other birds, waxwings derive colors from diet-based pigments and from synthesized colors. Because these color types differ in origin, each could provide different visual information about a bird's condition. This led to the testing …

Go to article

First Prev Next Last