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

Life Sciences Commons

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

Articles 1 - 29 of 29

Full-Text Articles in Life Sciences

Loss Of Enemy Resistance Among Introduced Populations Of St. John's Wort (Hypericum Perforatum), John L. Maron, Montserrat Vilà, John Arnason Dec 2004

Loss Of Enemy Resistance Among Introduced Populations Of St. John's Wort (Hypericum Perforatum), John L. Maron, Montserrat Vilà, John Arnason

Biological Sciences Faculty Publications

The Evolution of Increased Competitive Ability (EICA) hypothesis predicts that introduced plants should lose enemy resistance and in turn evolve increased size or fecundity. We tested the first prediction of this hypothesis by growing introduced North American and native European genotypes of St. John's Wort (Hypericum perforatum) in common gardens in the state of Washington, USA, and in Girona, Spain. In both gardens we measured levels of hypericin and pseudohypericin (and in Washington, hypericide)— compounds known to be toxic to generalist pathogens and herbivores. In a third common garden, in Spain, we experimentally manipulated native pathogen pressure (by treating ...


Soil Biota Facilitate Exotic Acer Invasions In Europe And North America, Kurt O. Reinhart, Ragan M. Callaway Dec 2004

Soil Biota Facilitate Exotic Acer Invasions In Europe And North America, Kurt O. Reinhart, Ragan M. Callaway

Biological Sciences Faculty Publications

The primary hypothesis for successful exotic plant invasions is that the invaders have escaped the specialist consumers that control them (Enemy Release Hypothesis). However, few studies have rigorously tested this assertion with biogeographical experiments or considered the effects of soil organisms. We tested the Enemy Release Hypothesis and the enhanced role of mutualisms by comparing density patterns of the North American Acer negundo and European A. platanoides trees in their native and nonnative ranges. Invaders that have escaped their natural enemies are predicted to attain greater densities in nonnative than native ranges. To determine whether interactions with soil biota could ...


Reconstitution Of Copii Vesicle Fusion To Generate A Pre-Golgi Intermediate Compartment, Dalu Xu, Jesse C. Hay Nov 2004

Reconstitution Of Copii Vesicle Fusion To Generate A Pre-Golgi Intermediate Compartment, Dalu Xu, Jesse C. Hay

Biological Sciences Faculty Publications

What is the first membrane fusion step in the secretory pathway? In mammals, transport vesicles coated with coat complex (COP) II deliver secretary cargo to vesicular tubular clusters (VTCs) that ferry cargo from endoplasmic reticulum exit sites to the Golgi stack. However, the precise origin of VTCs and the membrane fusion step(s) involved have remained experimentally intractable. Here, we document in vitro direct tethering and SNARE-dependent fusion of endoplasmic reticulum-derived COPII transport vesicles to form larger cargo containers. The assembly did not require detectable Golgi membranes, preexisting VTCs, or CON function. Therefore, COPII vesicles appear to contain all of ...


Evaluating Forensic Dna Evidence: Essential Elements Of A Competent Defense Review, Dan E. Krane Nov 2004

Evaluating Forensic Dna Evidence: Essential Elements Of A Competent Defense Review, Dan E. Krane

Biological Sciences Faculty Publications

No abstract provided.


The Effects Of Postfire Salvage Logging On Aquatic Ecosystems In The American West, J. R. Karr, Jj Rhodes, Gw Minshall, F. Richard Hauer, R. L. Beschta, C. A. Frissell, D. A. Perry Nov 2004

The Effects Of Postfire Salvage Logging On Aquatic Ecosystems In The American West, J. R. Karr, Jj Rhodes, Gw Minshall, F. Richard Hauer, R. L. Beschta, C. A. Frissell, D. A. Perry

Biological Sciences Faculty Publications

Recent changes in the forest policies, regulations, and laws affecting public lands encourage postfire salvage logging, an activity that all too often delays or prevents recovery. In contrast, the 10 recommendations proposed here can improve the condition of watersheds and aquatic ecosystems.


Evaluating Forensic Dna Evidence, Dan E. Krane Oct 2004

Evaluating Forensic Dna Evidence, Dan E. Krane

Biological Sciences Faculty Publications

No abstract provided.


Forensic Dna Evidence: Collection, Mixtures, And Degradation, Dan E. Krane Oct 2004

Forensic Dna Evidence: Collection, Mixtures, And Degradation, Dan E. Krane

Biological Sciences Faculty Publications

No abstract provided.


The Signal Peptide Of The Junín Arenavirus Envelope Glycoprotein Is Myristoylated And Forms An Essential Subunit Of The Mature G1-G2 Complex, Joanne York, Victor Romanowski, Min Lu, Jack H. Nunberg Oct 2004

The Signal Peptide Of The Junín Arenavirus Envelope Glycoprotein Is Myristoylated And Forms An Essential Subunit Of The Mature G1-G2 Complex, Joanne York, Victor Romanowski, Min Lu, Jack H. Nunberg

Biological Sciences Faculty Publications

Arenaviruses comprise a diverse family of rodent-borne viruses that are responsible for recurring and emerging outbreaks of viral hemorrhagic fevers worldwide. The Junin virus, a member of the New World arenaviruses, is endemic to the pampas grasslands of Argentina and is the etiologic agent of Argentine hemorrhagic fever. In this study, we have analyzed the assembly and function of the Junin virus envelope glycoproteins. The mature envelope glycoprotein complex is proteolytically processed from the GP-C precursor polypeptide and consists of three noncovalently associated subunits, G1, G2, and a stable 58-amino-acid signal peptide. This tripartite organization is found both on virions ...


Novel Weapons: Invasive Success And The Evolution Of Increased Competitive Ability, Ragan M. Callaway, Wendy M. Ridenour Oct 2004

Novel Weapons: Invasive Success And The Evolution Of Increased Competitive Ability, Ragan M. Callaway, Wendy M. Ridenour

Biological Sciences Faculty Publications

When introduced to new habitats by humans, some plant species become much more dominant. This is primarily attributed to escape from specialist consumers. Release from these specialist enemies is also thought by some to lead to the evolution of increased competitive ability, driven by a decrease in the plant's resource allocation to consumer defense and an increase in allocation to size or fecundity. Here, we discuss a new theory for invasive success – the “novel weapons hypothesis”. We propose that some invaders transform because they possess novel biochemical weapons that function as unusually powerful allelopathic agents, or as mediators of ...


Facultative Altitudinal Movements By Mountain White-Crowned Sparrows (Zonotrichia Leucophrys Oriantha) In The Sierra Nevada, Thomas P. Hahn, Keith W. Sockman, Creagh W. Breuner, Martin L. Morton Oct 2004

Facultative Altitudinal Movements By Mountain White-Crowned Sparrows (Zonotrichia Leucophrys Oriantha) In The Sierra Nevada, Thomas P. Hahn, Keith W. Sockman, Creagh W. Breuner, Martin L. Morton

Biological Sciences Faculty Publications

Mountain White-crowned Sparrows (Zonotrichia leucophrys oriantha) winter in Mexico and often arrive in the vicinity of their breeding grounds in the Sierra Nevada well before nesting is possible. Arrival at Tioga Pass, Califomia (elevation 3,030 m), usually occurs in early May, but residual winter snow and adverse weather can delay nesting for weeks. We used radiotelemetry to determine whether prebreeding Mountain White-crowned Sparrows engaged in weather-related altitudinal movements during the waiting period between the end of spring migration and onset of breeding during 1995-2001, with a range of residual winter snowpacks. Interannual variation in arrival date and onset of ...


Determining Rates Of Change And Evaluating Group-Level Resiliency Differences In Hyporheic Microbial Communities In Response To Fluvial Heavy-Metal Deposition, Kevin P. Feris, Philip W. Ramsey, Matthias Rillig, Johnnie N. Moore, James E. Gannon, William E. Holben Aug 2004

Determining Rates Of Change And Evaluating Group-Level Resiliency Differences In Hyporheic Microbial Communities In Response To Fluvial Heavy-Metal Deposition, Kevin P. Feris, Philip W. Ramsey, Matthias Rillig, Johnnie N. Moore, James E. Gannon, William E. Holben

Biological Sciences Faculty Publications

Prior field studies by our group have demonstrated a relationship between fluvial deposition of heavy metals and hyporheic-zone microbial community structure. Here, we determined the rates of change in hyporheic microbial communities in response to heavy-metal contamination and assessed group-level differences in resiliency in response to heavy metals. A controlled laboratory study was performed using 20 flowthrough river mesocosms and a repeated-measurement factorial design. A single hyporheic microbial community was exposed to five different levels of an environmentally relevant metal treatment (0, 4, 8, 16, and 30% sterilized contaminated sediments). Community-level responses were monitored at 1, 2, 4, 8, and ...


High Polymorphism In The K-Casein (Csn3) Gene From Wild And Domestic Caprine Species Revealed By Dna Sequencing, Oliver C. Jann, Eva-Maria Prinzenberg, Gordon Luikart, Ana Caroli, Georg Erhardt Jun 2004

High Polymorphism In The K-Casein (Csn3) Gene From Wild And Domestic Caprine Species Revealed By Dna Sequencing, Oliver C. Jann, Eva-Maria Prinzenberg, Gordon Luikart, Ana Caroli, Georg Erhardt

Biological Sciences Faculty Publications

We assessed polymorphisms in exon IV of the k-casein gene (CSN3) in ten different breeds of domestic goat (Capra hircus) from three continents and in three related wild caprine taxa (Capra ibex, Capra sibirica and Capra aegagrus). Thirty-five DNA samples were sequenced within a 558 bp fragment of exon IV. Nine polymorphic sites were identified in domestic goat, including four new polymorphisms. In addition to four previously described polymorphic positions, a total of 13 polymorphisms allowed the identification of 13 DNA variants, corresponding to 10 protein variants. Because of conflicting nomenclature of these variants, we propose a standardized allele designation ...


Evolution Of Morphological Integration. I. Functional Units Channel Stress-Induced Variation In Shrew Mandibles, Alexander V. Badyaev, Kerry R. Foresman Jun 2004

Evolution Of Morphological Integration. I. Functional Units Channel Stress-Induced Variation In Shrew Mandibles, Alexander V. Badyaev, Kerry R. Foresman

Biological Sciences Faculty Publications

Stress-induced deviations from normal development are often assumed to be random, yet their accumulation and expression can be influenced by patterns of morphological integration within an organism. We studied within-individual developmental variation ( fluctuating asymmetry) in the mandible of four shrew species raised under normal and extreme environments. Patterns of among-individual variation and fluctuating asymmetry were strongly concordant in traits that were involved in the attachment of the same muscles (i.e., functionally integrated traits), and fluctuating asymmetry was closely integrated among these traits, implying direct developmental interactions among traits involved in the same function. Stress-induced variation was largely confined to ...


Role Of Hydrophobic Residues In The Central Ectodomain Of Gp41 In Maintaining The Association Between Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Subunits Gp120 And Gp41, Joanne York, Jack H. Nunberg May 2004

Role Of Hydrophobic Residues In The Central Ectodomain Of Gp41 In Maintaining The Association Between Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Subunits Gp120 And Gp41, Joanne York, Jack H. Nunberg

Biological Sciences Faculty Publications

The interaction between the gp120 and gp41 subunits of the human immunodeficiency virus envelope glycoprotein serves to stabilize the virion form of the complex and to transmit receptor-induced conformational changes in gp120 to trigger the membrane fusion activity of gp41. In this study, we used site-directed mutagenesis to identify amino acid residues in the central ectodomain of gp41 that contribute to the stability of the gp120-gp41 association. We identified alanine mutations at six positions, including four tryptophan residues, which result in mutant envelope glycoprotein complexes that fail to retain gp120 on the cell surface. These envelope glycoproteins readily shed their ...


Rapid Evolution Of An Invasive Plant, John L. Maron, Montserrat Vilà, Riccardo Bommarco, Sarah Elmendorf, Paul Beardsley May 2004

Rapid Evolution Of An Invasive Plant, John L. Maron, Montserrat Vilà, Riccardo Bommarco, Sarah Elmendorf, Paul Beardsley

Biological Sciences Faculty Publications

Exotic plants often face different conditions from those experienced where they are native. The general issue of how exotics respond to unfamiliar environments within their new range is not well understood. Phenotypic plasticity has historically been seen as the primary mechanism enabling exotics to colonize large, environmentally diverse areas. However, new work indicates that exotics can evolve quickly, suggesting that contemporary evolution may be more important in invasion ecology than previously appreciated. To determine the influence of contemporary evolution, phenotypic plasticity, and founder effects in affecting phenotypic variation among introduced plants, we compared the size, fecundity, and leaf area of ...


Gc Fractionation Enhances Microbial Community Diversity Assessment And Detection Of Minority Populations Of Bacteria By Denaturing Gradient Gel Electrophoresis, William Holben, Keving P. Feris, Anu Kettunen, Juha H. A. Apajalahti Apr 2004

Gc Fractionation Enhances Microbial Community Diversity Assessment And Detection Of Minority Populations Of Bacteria By Denaturing Gradient Gel Electrophoresis, William Holben, Keving P. Feris, Anu Kettunen, Juha H. A. Apajalahti

Biological Sciences Faculty Publications

Effectively and accurately assessing total microbial community diversity is one of the primary challenges in modern microbial ecology. This is particularly true with regard to the detection and characterization of unculturable populations and those present only in low abundance. We report a novel strategy, GC fractionation combined with denaturing gradient gel electrophoresis (GC-DGGE), which combines mechanistically different community analysis approaches to enhance assessment of microbial community diversity and detection of minority populations of microbes. This approach employs GC fractionation as an initial step to reduce the complexity of the community in each fraction. This reduced complexity facilitates subsequent detection of ...


Soil Fungi Alter Interactions Between The Invader Centaurea Maculosa And North American Natives, Ragan M. Callaway, Giles C. Thelen, Sara Barth, Philip W. Ramsey, James E. Gannon Apr 2004

Soil Fungi Alter Interactions Between The Invader Centaurea Maculosa And North American Natives, Ragan M. Callaway, Giles C. Thelen, Sara Barth, Philip W. Ramsey, James E. Gannon

Biological Sciences Faculty Publications

Soil microbes may affect the way exotic invasive plants interact with native neighbors. We investigated the effects of soil fungi on interactions between the invasive weed Centaurea maculosa (spotted knapweed) and six species native to the intermountain prairies of the northwestern United States. We also compared the effect of C. maculosa on the composition of the soil microbial community to that of the native species. In the field, fungicide (Benomyl) reduced AM mycorrhizal colonization of C. maculosa roots by >80%. Fungicide did not significantly reduce non-AM fungi. When grown alone, the biomass of C. maculosa was not affected by the ...


Seasonal Dynamics Of Shallow-Hyporheic-Zone Microbial Community Structure Along A Heavy-Metal Contamination Gradient, Kevin P. Feris, Philip W. Ramsey, Chris Frazar, Matthias Rillig, Johnnie N. Moore, William E. Holben Apr 2004

Seasonal Dynamics Of Shallow-Hyporheic-Zone Microbial Community Structure Along A Heavy-Metal Contamination Gradient, Kevin P. Feris, Philip W. Ramsey, Chris Frazar, Matthias Rillig, Johnnie N. Moore, William E. Holben

Biological Sciences Faculty Publications

Heavy metals contaminate numerous freshwater streams and rivers worldwide. Previous work by this group demonstrated a relationship between the structure of hyporheic microbial communities and the fluvial deposition of heavy metals along a contamination gradient during the fall season. Seasonal variation has been documented in microbial communities in numerous terrestrial and aquatic environments, including the hyporheic zone. The current study was designed to assess whether relationships between hyporheic microbial community structure and heavy-metal contamination vary seasonally by monitoring community structure along a heavy-metal contamination gradient for more than a year. No relationship between total bacterial abundance and heavy metals was ...


Variation In Sulfide Tolerance Of Photosystem Ii In Phylogenetically Diverse Cyanobacteria From Sulfidic Habitats, Scott R. Miller, Brad M. Bebout Feb 2004

Variation In Sulfide Tolerance Of Photosystem Ii In Phylogenetically Diverse Cyanobacteria From Sulfidic Habitats, Scott R. Miller, Brad M. Bebout

Biological Sciences Faculty Publications

Physiological and molecular phylogenetic approaches were used to investigate variation among 12 cyanobacterial strains in their tolerance of sulfide, an inhibitor of oxygenic photosynthesis. Cyanobacteria from sulfidic habitats were found to be phylogenetically diverse and exhibited an approximately 50-fold variation in photosystem II performance in the presence of sulfide. Whereas the degree of tolerance was positively correlated with sulfide levels in the environment, a strain's phenotype could not be predicted from the tolerance of its closest relatives. These observations suggest that sulfide tolerance is a dynamic trait primarily shaped by environmental variation. Despite differences in absolute tolerance, similarities among ...


Splicing Affects Presentation Of Rna Dimerization Signals In Hiv-2 In Vitro, Jean-Marc Lanchy, Quenna N. Szafran, J. Stephen Lodmell Jan 2004

Splicing Affects Presentation Of Rna Dimerization Signals In Hiv-2 In Vitro, Jean-Marc Lanchy, Quenna N. Szafran, J. Stephen Lodmell

Biological Sciences Faculty Publications

During retroviral replication, full-length viral RNAs are encapsidated into new virus particles, while spliced RNAs are excluded. The Retroviridae are unique among viruses in that infectious viral particles contain a dimer of two identical genomic RNA strands. A variety of experimental data has suggested that dimerization and encapsidation of full-length viral RNAs are linked processes, although whether dimerization is a prerequisite for encapsidation, or conversely, dimerization follows encapsidation, has not been firmly established. If dimerization was the sole determinant for encapsidation, then spliced viral RNAs might be expected to display a reduced capacity for dimerization, resulting in their exclusion from ...


Chemical Defenses In Garlic Mustard (Alliaria Petiolata) And Their Potential Role In Species Interactions In Forest Understories, Don Cipollini Jan 2004

Chemical Defenses In Garlic Mustard (Alliaria Petiolata) And Their Potential Role In Species Interactions In Forest Understories, Don Cipollini

Biological Sciences Faculty Publications

Garlic mustard [Alliaria petiolata [(M. Bieb) Cavara & Grande; Brassicaceae] is a European native biennial herb, first recorded on Long Island, NY in the 1860s, and is expanding rapidly in northeastern and midwestern forests in the U.S. and in southern Canada. Garlic mustard flourishes in moist woodlands with moderate exposure to light, but it can grow in a diversity of other habitats. It is found in natural areas, woodlots, and along edges of agricultural fields and lawns throughout North America. Several life history traits likely contribute to the invasiveness of this species. It has a high inbreeding rate and can produce ...


Isolation And Characterization Of Mycobacteria From Striped Bass Morone Saxatilis From The Chesapeake Bay, Martha W. Rhodes, Howard Kator, Ilsa Kaattari, David Gauthier, Wolfgang Vogelbein, Christopher A. Ottinger Jan 2004

Isolation And Characterization Of Mycobacteria From Striped Bass Morone Saxatilis From The Chesapeake Bay, Martha W. Rhodes, Howard Kator, Ilsa Kaattari, David Gauthier, Wolfgang Vogelbein, Christopher A. Ottinger

Biological Sciences Faculty Publications

Mycobacteriosis in striped bass Morone saxatilisof Chesapeake Bay, USA, was first diagnosed in 1997 based on the presence of granulomatous inflammation and acid-fast bacteria in skin and spleen. To confirm histopathology, bacteriological detection and identification of mycobacteria were begun using splenic tissue from fish with and without skin ulcerations. On the basis of initial studies using a variety of selective and nonselective media, decontamination, homogenization and incubation conditions, a simple and quantitative recovery method using aseptic necropsy of splenic tissue was developed. Optimal recovery was obtained by spread-plating homogenates on Middlebrook 7H10 agar with incubation for 3 mo at ...


A New Pathogenic Virus In The Caribbean Spiny Lobster Panulirus Argus From The Florida Keys, Jeffrey D. Shields, Donald C. Behringer Jr. Jan 2004

A New Pathogenic Virus In The Caribbean Spiny Lobster Panulirus Argus From The Florida Keys, Jeffrey D. Shields, Donald C. Behringer Jr.

Biological Sciences Faculty Publications

A pathogenic virus was diagnosed from juvenile Caribbean spiny lobsters Panulirus argus from the Florida Keys. Moribund lobsters had characteristically milky hemolymph that did not clot. Altered hyalinocytes and semigranulocytes, but not granulocytes, were observed with light microscopy. Infected hemocytes had emarginated, condensed chromatin, hypertrophied nuclei and faint eosinophilic Cowdry-type-A inclusions. In some cases, infected cells were observed in soft connective tissues. With electron microscopy, unenveloped, nonoccluded, icosahedral virions (182 +/- 9 nm SD) were diffusely spread around the inner periphery of the nuclear envelope. Virions also occurred in loose aggregates in the cytoplasm or were free in the hemolymph. Assembly ...


Identification And Characterization Of A Nontypeable Haemophilus Influenzae Putative Toxin-Antitoxin Locus, Dayle A. Daines, Justin Jarisch, Arnold L. Smith Jan 2004

Identification And Characterization Of A Nontypeable Haemophilus Influenzae Putative Toxin-Antitoxin Locus, Dayle A. Daines, Justin Jarisch, Arnold L. Smith

Biological Sciences Faculty Publications

Background: Certain strains of an obligate parasite of the human upper respiratory tract, nontypeable Haemophilus influenzae (NTHi), can cause invasive diseases such as septicemia and meningitis, as well as chronic mucosal infections such as otitis media. To do this, the organism must invade and survive within both epithelial and endothelial cells. We have identified a facilitator of NT(Hi) survival inside human cells, virulence-associated protein D (vapDHi, encoded by gene H10450). Both vapDHi and a flanking gene, H10451, exhibit the genetic and physical characteristics of a toxin/antitoxin ( TA) locus, with VapDHi serving as the toxin ...


Ultrastructure Of Mycobacterium Marinum Granuloma In Striped Bass Morone Saxatilis, D. T. Gauthier, W. K. Vogelbein, C. A. Ottinger Jan 2004

Ultrastructure Of Mycobacterium Marinum Granuloma In Striped Bass Morone Saxatilis, D. T. Gauthier, W. K. Vogelbein, C. A. Ottinger

Biological Sciences Faculty Publications

An emerging epizootic of mycobacteriosis currently threatens striped bass Morone saxatilis populations in Chesapeake Bay, USA. Several species of mycobacteria, including Mycobacterium marinum, species resembling M. avium, M. gordonae, M. peregrinum, M. scrofulaceum and M. terrae, and the new species M. shottsii have been isolated from diseased and healthy bass. In this study, we describe the ultrastructure of developing M. marinum granulomas in experimentally infected bass over a period of 45 wk. The primary host response to injected mycobacteria was formation of large macrophage aggregations containing phagocytosed bacilli. M. marinum were always contained within phagosomes. Close association of lysosomes with ...


Dissecting The Loci Of Low-Level Quinine Resistance In Malaria Parasites, Michael T. Ferdig, Roland A. Cooper, Jianbing Mu, Bingbing Deng, Deirdre A. Joy, Xin-Zhuan Su, Thomas E. Wellems Jan 2004

Dissecting The Loci Of Low-Level Quinine Resistance In Malaria Parasites, Michael T. Ferdig, Roland A. Cooper, Jianbing Mu, Bingbing Deng, Deirdre A. Joy, Xin-Zhuan Su, Thomas E. Wellems

Biological Sciences Faculty Publications

Quinine (QN) remains effective against Plasmodium falciparum, but its decreasing efficacy is documented from different continents. Multiple genes are likely to contribute to the evolution of QN resistance. To locate genes contributing to QN response variation, we have searched a P. falciparum genetic cross for quantitative trait loci (QTL). Results identify additive QTL in segments of chromosomes (Chrs) 13, 7 and 5, and pairwise effects from two additional loci of Chrs 9 and 6 that interact, respectively, with the QTL of Chrs 13 and 7. The mapped segments of Chrs 7 and 5 contain pfcrt, the determinant of chloroquine resistance ...


Metabolic Rate Models And The Substitutability Of Predator Populations, David R. Chalcraft, William J. Resetarits Jr. Jan 2004

Metabolic Rate Models And The Substitutability Of Predator Populations, David R. Chalcraft, William J. Resetarits Jr.

Biological Sciences Faculty Publications

1. Much of the debate surrounding the consequences of biodiversity loss centres around the issue of whether different species are functionally similar in their effects on ecological processes. In this study, we examined whether populations consisting of smaller, more abundant individuals are functionally similar to populations of the same species with larger, fewer individuals.
2. We manipulated the biomass and density of banded sunfish (Enneacanthus obesus) and measured their impact on populations of Southern leopard frog (Rana sphenocephala) larvae. We also evaluated the ability of models relating metabolic rate to body size to predict the relative impacts of populations that ...


Comparative Life Histories Of Georgia And Virginia Cotton Rats, Bradley J. Bergstrom, Robert K. Rose Jan 2004

Comparative Life Histories Of Georgia And Virginia Cotton Rats, Bradley J. Bergstrom, Robert K. Rose

Biological Sciences Faculty Publications

Adult hispid cotton rats (Sigmodon hispidus) were collected from the field monthly for >2 years from populations near the northern edge of their range in Virginia and contemporaneously from south-central Georgia. Body measurements and weights were taken at capture, and after dissection embryos, corpora lutea, and placental scars were counted and measured; testes and seminal vesicles were dissected out, measured, and weighed. This allowed comparison of several life-history parameters between the populations and tests of several life-history hypotheses. The breeding season was up to 2 months longer in Georgia than in Virginia, where there was typically a 3-month or longer ...


On The Ecological Status Of The Concept "Boundary Conditions" - A Few Methodological Remarks, Lubomira Burchardt, Krzystof Lastowski, Harold G. Marshall Jan 2004

On The Ecological Status Of The Concept "Boundary Conditions" - A Few Methodological Remarks, Lubomira Burchardt, Krzystof Lastowski, Harold G. Marshall

Biological Sciences Faculty Publications

Plant and animal populations are frequently found in habitats where the environmental conditions are considered extreme or challenging for life form to exist. These conditions may be classified as either: (1) Supreme: a situation characteristic of degradation conditions where only a few species live under stress, and (2) Extra-ordinary: habitats that provide high biodiversity that are under stress conditions. Due to the differences in what we consider extreme conditions, it is necessary to distinguish between these two categories, because they are not comparable. Our presentation will include examples of these two extreme environmental categories.