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A Fossil Blue Marlin (Makaira Nigricans Lacépède) From The Middle Facies Of The Trinidad Formation (Upper Miocene To Upper Pliocene), San José Del Cabo Basin, Baja California Sur, México, Harry L. Fierstine, Shelton P. Applegate, Gerardo González-Barba, Tobias Schwennicke, Luis Espinosa-Arrubarrena Jan 2001

A Fossil Blue Marlin (Makaira Nigricans Lacépède) From The Middle Facies Of The Trinidad Formation (Upper Miocene To Upper Pliocene), San José Del Cabo Basin, Baja California Sur, México, Harry L. Fierstine, Shelton P. Applegate, Gerardo González-Barba, Tobias Schwennicke, Luis Espinosa-Arrubarrena

Biological Sciences

A large fossil skull and several rostra of Makaira nigricans Lacépède, 1802 (Perciformes: Istiophoridae), as well as some less diagnostic istiophorid remains, have been recovered from the middle facies of the Trinidad Formation near Rancho Algodones, San José del Cabo Basin, Baja California Sur, México. These are the only bill fish specimens known from fossiliferous deposits located between southern California and Panama. Based on published accounts of the presence of nannofossils and planktonic foraminifera, and additional field work, we conclude that the age of the study area is late Miocene to late Pliocene. Based on the habitat preferences of recent …


Radiocesium In Fish From The Savannah River And Steel Creek: Potential Food Chain Exposure To The Public, Joanna Burger, Karen F. Gaines, J. D. Peles, W. L. Stephens Jr., C. Shane Boring, I. Lehr Brisbin Jr., J. Snodgrass, A. L. Bryan Jr., M. H. Smith, M. Gochfeld Jan 2001

Radiocesium In Fish From The Savannah River And Steel Creek: Potential Food Chain Exposure To The Public, Joanna Burger, Karen F. Gaines, J. D. Peles, W. L. Stephens Jr., C. Shane Boring, I. Lehr Brisbin Jr., J. Snodgrass, A. L. Bryan Jr., M. H. Smith, M. Gochfeld

Faculty Research & Creative Activity

This study examined radiocesium (137Cs) levels in fish from the vicinity of the Department of Energy's Savannah River Site (SRS), a former nuclear weapons production facility in South Carolina. Fish from the Savannah River were sampled above (upstream), along, and below (downstream) the SRS, and from Steel Creek, a tributary that runs through the SRS. There was some off-site contamination of 137Cs in the Savannah River watershed due to low-level releases from past nuclear production on the SRS. The null hypotheses tested were that there would be no differences in 137Cs levels as a function of location along the river, …


A New Wildlife Sighting Reporting And Database System For Lassen Volcanic National Park, John D. Perrine, Jonathan F. Arnold Jan 2001

A New Wildlife Sighting Reporting And Database System For Lassen Volcanic National Park, John D. Perrine, Jonathan F. Arnold

Biological Sciences

Visitors and employees in national parks may observe species of interest to wildlife biologists and resource managers. These sightings are useful to researchers and managers only if the data can be efficiently acquired, stored and retrieved for analysis.· We identified several problems in the wildlife sightings reporting system at Lassen Volcanic National Park, including a confusing array of reporting forms; incomplete contact information for the reporter; insufficient reporting of the animal's description, behavior and location; and a cumbersome data entry and retrieval system. We developed a new system to correct these problems. A single reporting form corrects the aforementioned data …


Effects Of Collection, Transport, And Redeployment Methods On Natural Mortality Of Rangia Cuneata (Mactridae) Used In Biomonitoring Studies, Eugene G. Maurakis, David V. Grimes, William C. Gretes Jan 2001

Effects Of Collection, Transport, And Redeployment Methods On Natural Mortality Of Rangia Cuneata (Mactridae) Used In Biomonitoring Studies, Eugene G. Maurakis, David V. Grimes, William C. Gretes

Virginia Journal of Science

Sporadic, high mortality in test populations of wedge clams (Rangia cuneata) has limited the potential for using this otherwise desirable test organism in biomonitoring studies. To determine whether high mortality was due to ontogenic or experimental variables, a two-phased study was conducted. In phase I, mortality of collected and re-deployed wedge clams, subjected to varying transport conditions, was determined at 7, 14, 21 and 60 days re-deployment. The use of three transport times (1, 2, 3 hr.), two vehicle conditions (open, closed) and three transport treatments (open, closed, iced containers) yielded 18 test groups. Individual test group mortalities …


Revisiting Women And Feminism In Developmental Biology, Scott F. Gilbert, K. A. Rader Jan 2001

Revisiting Women And Feminism In Developmental Biology, Scott F. Gilbert, K. A. Rader

Biology Faculty Works

No abstract provided.


Oogenesis In Caenorhabditis Elegans, Eleanor M. Maine Jan 2001

Oogenesis In Caenorhabditis Elegans, Eleanor M. Maine

Biology - All Scholarship

Oogenesis is the process of forming the female gamete, i.e., the ovum or egg. In Caenorhabditis elegans, gametes derive from a tissue called the germ line, which is specified early in embryonic development. Two major events occur during oogenesis: the oocyte precursor germ cell undergoes meiotic division and it accumulates substantial cytoplasm. In meiosis, two sequential rounds of cell division produce a haploid egg, with only one copy of each chromosome, from the diploid oocyte precursor cell. Simultaneously, a large volume of cytoplasm is accumulated; it contains yolk and numerous other components that are essential for early embryonic development. Meiotic …


Rnai As A Tool For Understanding Germline Development In Caenorhabditis Elegans: Uses And Cautions, Eleanor M. Maine Jan 2001

Rnai As A Tool For Understanding Germline Development In Caenorhabditis Elegans: Uses And Cautions, Eleanor M. Maine

Biology - All Scholarship

RNA-mediated genetic interference (RNAi) has become a very useful tool for analyzing gene function in development and other processes. RNAi can be used as a complement to traditional genetic studies or as a primary means of determining biological function. However, the efficacy of RNAi depends on a variety of factors that the researcher must take into consideration. This review focuses on germline development in the nematode, Caenorhabditis elegans, and discusses the uses and limitations of RNAi in providing new information about gene function as well as the possible endogenous role RNAi plays in germline physiology.


Continuity And Change: Paradigm Shifts In Neural Induction, Scott F. Gilbert Jan 2001

Continuity And Change: Paradigm Shifts In Neural Induction, Scott F. Gilbert

Biology Faculty Works

No abstract provided.


Antipredator Response Of Red-Backed Salamanders (Plethodon Cinereus) To Chemical Cues From Garter Snakes (Thamnophis Sirtalis) Laboratory And Field Experiments, Aaron M. Sullivan, John C. Maerz, Dale M. Madison Jan 2001

Antipredator Response Of Red-Backed Salamanders (Plethodon Cinereus) To Chemical Cues From Garter Snakes (Thamnophis Sirtalis) Laboratory And Field Experiments, Aaron M. Sullivan, John C. Maerz, Dale M. Madison

Faculty Publications - Department of Biological & Molecular Science

Recent laboratory studies show that terrestrial salamanders exhibit anti-predatory behavior in response to chemical cues from predators, but no studies have confirmed these results in the field where environmental and social factors may influence responses. We examined the character and duration of anti-predator behavior of red-backed salamanders (Plethodon cinereus) exposed to control stimuli and chemical cues from garter snakes (Thamnophis sirtalis) in evening laboratory and field trials. In the laboratory, P. cinereus significantly avoided snake rinse for 36 h. In the field, P. cinereus exposed to the same cues delayed emergence from refugia for 2 h, …


Effects Of Hydroperiod On Metamorphosis In Rana Sphenocephala, Travis J. Ryan, Christopher T. Winne Jan 2001

Effects Of Hydroperiod On Metamorphosis In Rana Sphenocephala, Travis J. Ryan, Christopher T. Winne

Scholarship and Professional Work - LAS

Hydroperiod, the time a temporary pond holds water, is an important factor influencing recruitment in amphibian populations and structuring amphibian communities. We conducted an experiment to test the effect of hydroperiod on metamorphic traits of the southern leopard frog (Rana sphenocephala), a common amphibian in the southeastern United States. We reared larval R. sphenocephala in artificial ponds at a density of 32 larvae per tank (initial volume = approximately 650 liter). We dried the tanks according to natural patterns, using three different hydroperiods (60, 75 and 90 d). Experimental hydroperiods had a significant effect on the number of …


Fitness Trade-Offs Select For Semelparous Reproduction In An Extreme Environment, Felisa Smith, Eric Charnov Jan 2001

Fitness Trade-Offs Select For Semelparous Reproduction In An Extreme Environment, Felisa Smith, Eric Charnov

Biology Faculty & Staff Publications

No abstract provided.


Nitric Oxide And Cnidarian-Dinoflagellate Symbioses: Pieces Of A Puzzle, Henry G. Trapido-Rosenthal, Katherine H. Sharp Jan 2001

Nitric Oxide And Cnidarian-Dinoflagellate Symbioses: Pieces Of A Puzzle, Henry G. Trapido-Rosenthal, Katherine H. Sharp

Arts & Sciences Faculty Publications

The presence of nitric oxide synthase (NOS) activity is demonstrated in the tropical marine cnidarian Aiptasia pallida and in its symbiotic dinoflagellate algae, Symbiodinium bermudense. Enzyme activity was assayed by measuring the conversion of arginine to citrulline. Biochemical characterization of NOS from Aiptasia was characterized with respect to cellular localization, substrate and cofactor requirements, inhibitors, and kinetics. In response to acute temperature shock, anemones retracted their tentacles. Animals subjected to such stress had lower NOS activities than did controls. Treatment with NOS inhibitors caused tentacular retraction, while treatment with the NOS substrate L-arginine inhibited this response to stress, as did …


Microsatellite Analysis Of Female Mating Behaviour In Lek-Breeding Sage Grouse, Katy Semple, Robert K. Wayne, Robert M. Gibson Jan 2001

Microsatellite Analysis Of Female Mating Behaviour In Lek-Breeding Sage Grouse, Katy Semple, Robert K. Wayne, Robert M. Gibson

School of Biological Sciences: Faculty Publications

We used microsatellite DNA markers to genotype chicks in 10 broods of lek-breeding sage grouse, Centrocercus urophasianus, whose mothers’ behaviour was studied by radio tracking and observing leks. Previous behavioural studies suggested that almost all matings are performed by territorial males on leks and that multiple mating is rare. Two broods (20%) were sired by more than one male. Genetic analyses of the broods of eight females that visited an intensively studied lek were consistent with behavioural observations. Four females observed mating produced singly sired broods and males other than the individual observed copulating were excluded as sires for most …


Fisheries Occasional Publication No. 31 - Feeding Lupins To Fish: A Review Of The Nutritional And Biological Value Of Lupins In Aquaculture Feeds, Brett Glencross Jan 2001

Fisheries Occasional Publication No. 31 - Feeding Lupins To Fish: A Review Of The Nutritional And Biological Value Of Lupins In Aquaculture Feeds, Brett Glencross

Fisheries Occasional Publications

Lupins are the harvested seed of species from the Lupinus genus, a group within the leguminous bean and pea family Fabaceae. Legumes are particularly valuable agricultural crops because of their capacity to provide a grain crop and also fix and return nitrogen to soils and improve the soil value for further cropping. The oilseeds, soybeans and peanuts are also leguminous plants, though traditionally they have been cropped for their oil value, whereas lupins, are cropped for both their protein and nitrogen fixing value (Gladstones, 1998; Perry et al., 1998).

The three key commercial species of lupins are L. angustifolius (Narrow-leafed …


Using Upper Boundary Constraints To Quantify Competitive Response Of Desert Annuals, Laura M. Lessin, Andrew R. Dyer, Deborah E. Goldberg Jan 2001

Using Upper Boundary Constraints To Quantify Competitive Response Of Desert Annuals, Laura M. Lessin, Andrew R. Dyer, Deborah E. Goldberg

Faculty Publications

Using a target-neighborhood approach with six annual dicot species in the Negev Desert of Israel, we tested whether neighborhood biomass constrained the upper limit of plant performance and if the slope of the upper boundary was correlated to species trait means, such as relative growth rate (RGR) and seed mass. Target individuals were measured in early spring and then collected at the onset of the dry season along with all naturally occurring neighbors within a 5-cm radius of the target. Using a minimum of 50 samples for each of the six target species, we found no significant relationships between target …


Application Of Green Fluorescent Protein As A Marker For Selection Of Transgenic Mouse Embryos Before Implantation, Haydar Bağiş, Levent Keski̇ntepe Jan 2001

Application Of Green Fluorescent Protein As A Marker For Selection Of Transgenic Mouse Embryos Before Implantation, Haydar Bağiş, Levent Keski̇ntepe

Turkish Journal of Biology

In this study, we evaluated the application of green fluorescent protein (GFP) from the jellyfish Aequorea victoria, for efficient selection of possible transgenic and non-mosaic mouse embryos after microinjection. We injected 353 one-cell mouse zygotes with a DNA fragment carrying Gfp gene under the control of \beta-actin gene promoter. Eighty-seven per cent (307 embryos) of the injected embryos survived after microinjection. The surviving embryos were cultured for an additional day and then analysed for detection of GFP expression using a standard fluorescein isothiocyanate (FITC) filter set attached to a microscope. In this analysis, 34 % of the two-cell stage embryos …


Nitric Oxide Synthase In The Skeletal Muscle And Arterioles Of Rats With Streptozotosin-Induced Diabetes Mellitus, Ci̇han Demi̇rci̇, Kadri̇ye Akgün Dar, İlhan Uyaner Jan 2001

Nitric Oxide Synthase In The Skeletal Muscle And Arterioles Of Rats With Streptozotosin-Induced Diabetes Mellitus, Ci̇han Demi̇rci̇, Kadri̇ye Akgün Dar, İlhan Uyaner

Turkish Journal of Biology

Nitric oxide synthase (NOS) that uses NADPH as a cofactor is an enzyme which produces nitric oxide (NO) from L-arginine. Endothelial-derived (eNOS), inducible (iNOS) and neuronal (nNOS) nitric oxide synthase are 3 known isoforms. Endothelial NO regulates the vascular tonus and causes the dilatation of vessels, while NOS localized in the sarcolemma of striated muscle plays a role in the regulation of muscle hemodynamics. Many authors have found differences in NO production in some pathological conditions such as diabetes mellitus (DM), hypertension and atherosclerosis. In this study, NADPH-diaphorase (NADPH-d) was histochemically employed to explore any changes in NO production associated …


Effects Of Photoperiod And Melatonin Infusions On Body Weight In Pinealectomized Juvenile Siberian Hamsters (Phodopus Sungorus), Bülent Gündüz, Alper Karakaş Jan 2001

Effects Of Photoperiod And Melatonin Infusions On Body Weight In Pinealectomized Juvenile Siberian Hamsters (Phodopus Sungorus), Bülent Gündüz, Alper Karakaş

Turkish Journal of Biology

We examined the effects of daily melatonin (Mel) infusions in pinealectomized prepubertal male Siberian hamsters in three different conditions. In one study we investigated the body weight maturation response to one hour daily infusions of 10 ng, 25 ng, or 50 ng of Mel in pinealectomized hamsters. Animals received, at day 15 of life, programmed subcutaneous infusions of Mel or vehicle at one of five time points (1900-2000, 2000-2100, 2100-2200, 2400-0100, and 0300-0400 hours) for 30 days. In long-day-born (16L) animals, Mel infusion right after lights off (2000-2100 hours) significantly inhibited body growth; this dose was ineffective at other times. …


Molecular Characterization Of The Gene Encoding For The Salivaricin B Activity And Its Flanking Sequences, Osman Çataloluk Jan 2001

Molecular Characterization Of The Gene Encoding For The Salivaricin B Activity And Its Flanking Sequences, Osman Çataloluk

Turkish Journal of Biology

Lactic acid bacteria (LAB) produce many different antimicrobial proteins, some of which have potential in food preservation. The molecular analysis of bacteriocins has gained much attention and has advanced rapidly in recent years, and it became routine to analyze the way in which bacteriocins are expressed and translocated. Since they are associated with foods of plant and animal origins, the shared interest is that they can be utilized as a vector to deliver the active constituents at the target in the gastrointestinal tract after digestion and be used in therapy. In this respect, the molecular pattern of the expression and …


Hydrologic Events And Water Quality In The Pigeon River, Ottawa County, Michigan, Neil W. Macdonald, Richard R. Rediske, Jonathan E. Van Denend Jan 2001

Hydrologic Events And Water Quality In The Pigeon River, Ottawa County, Michigan, Neil W. Macdonald, Richard R. Rediske, Jonathan E. Van Denend

Peer Reviewed Publications

The Pigeon River drains a 16,765-ha agricultural watershed in western Ottawa County, Michigan and discharges into south-central Lake Michigan. Extensive areas of wetlands in the upper watershed were drained in the 1920s, causing significantly altered hydrology characteristics by flashy discharges during storms and periods of snowmelt. We studied stream chemistry and hydrology for a four-year period between September, 1996, and October, 2000, to determine water quality status, to estimate annual nutrient exports, and to evaluate the effects of different seasonal flow types. Results of our study confirmed that the upper reaches of the Pigeon River experience chronically degraded water quality, …


Contrasts In Tick Innate Immune Responses To Borrelia Burgdorferi Challenge: Immuno-Tolerance In Ixodes Scapularis Versus Immunocompetence In Dermacentor Variabilis (Acari: Ixodidae)., Robert Johns, Jun Ohnishi, Anne Broadwater, Daniel E. Sonenshine, Aravinda M. Desilva, Wayne L. Hynes Jan 2001

Contrasts In Tick Innate Immune Responses To Borrelia Burgdorferi Challenge: Immuno-Tolerance In Ixodes Scapularis Versus Immunocompetence In Dermacentor Variabilis (Acari: Ixodidae)., Robert Johns, Jun Ohnishi, Anne Broadwater, Daniel E. Sonenshine, Aravinda M. Desilva, Wayne L. Hynes

Biological Sciences Faculty Publications

The blacklegged tick, Ixodes scapularis Say, transmits the Lyme disease spirochete (Borrelia burgdorferi), whereas the American dog tick, Dermacentor variabilis (Say), is unable to transmit the bacterium. We compared the innate immune response of these ticks against spirochetes directly inoculated into the hemocoel cavity of ticks. In I. scapularis, some Borrelia were found associated with hemocytes, while numerous other spiral-shaped, intact bacteria remained free in the hemolymph. In contrast, in D. variabilis only remnants of the bacteria were evident in the hemolymph, indicating lysis; intact spirochetes were rare. Spirochetes were observed bound to or within the organs …


Production Of Single-Cell Protein From Ram Horn Hydrolysate, Esabi̇ Başaran Kurbanoğlu Jan 2001

Production Of Single-Cell Protein From Ram Horn Hydrolysate, Esabi̇ Başaran Kurbanoğlu

Turkish Journal of Biology

Candida utilis NRRL Y-900 was grown on horn hydrolysate for single-cell protein production. First, ram horns obtained from slaughterhouse in Erzurum were hydrolyzed by physical and chemical methods and crude horn hydrolysate (CHH) was obtained. The contents of protein, nitrogen, ash, some minerals, total sugars and amino acids of CHH were determined and it was seen that it has sufficient organic and inorganic materials to allow its use as a substrate source in the production of single-cell protein. The CHH was enriched by addition of yeast extract, glucose and KH_2PO_4. The effects of different CHH concentrations (1, 2, 3, 4, …


Viral Control Of The European Pine Sawfly, Neodiprion Sertifer (Geoffroy) In Turkey, Mustafa Yaman, Remzi̇ye Nalçacioğlu, Zi̇hni̇ Demi̇rbağ Jan 2001

Viral Control Of The European Pine Sawfly, Neodiprion Sertifer (Geoffroy) In Turkey, Mustafa Yaman, Remzi̇ye Nalçacioğlu, Zi̇hni̇ Demi̇rbağ

Turkish Journal of Biology

The European pine sawfly, Neodiprion sertifer (Geoffr.) (Hymenoptera: Diprionidae), is a serious pest of pine plantations and ornamentals. Chemical pesticides used to control this pest have a detrimental effect on the environment. The Neodiprion sertifer nuclear polyhedrosis virus (NsNPV) frequently causes considerable decreases in the populations but doses not harm other animals or plants. In this study, we tested five different concentrations of NsNPV against the larvae of N. sertifer and showed viral infection using Giemsa staining. When a viral concentration of 5x10^9 PIB/ml (Polyhedral Inclusion Body) was utilized, larval mortality started on the fourth day and reached 90.4% on …


Invasion Of Mouse Fibroblasts And Macrophages By Human Isolates Of Agrobacterium, Karmon Leigh Kriechbaum Jan 2001

Invasion Of Mouse Fibroblasts And Macrophages By Human Isolates Of Agrobacterium, Karmon Leigh Kriechbaum

Honors Theses

In the past few decades there has been growing evidence that species of Agrobacterium can be opportunistic animal pathogens. One of these species is Agrobacterium tumefaciens, which for years has been studied as a plant pathogen. The results of one published experiment suggested that an Agrobacterium toxin could kill mice (12). Other strong evidence for Agrobacterium as an opportunistic human pathogen is the over fifty published clinical cases in which humans were infected by Agrobacterium species (3, 13-25). In almost all of these cases the patient was immunocompromised in some way and they often had an invasive procedure such as …


Aquaporin 5-Deficient Mouse Lungs Are Hyperresponsive To Cholinergic Stimulation, Carissa M. Krane, Christopher N. Fortner, Arthur R. Hand, Dennis W. Mcgraw, John N. Lorenz, Susan E. Wert, Jennifer E. Towne, Richard J. Paul, Jeffrey A. Whitsett, Anil G. Menon Jan 2001

Aquaporin 5-Deficient Mouse Lungs Are Hyperresponsive To Cholinergic Stimulation, Carissa M. Krane, Christopher N. Fortner, Arthur R. Hand, Dennis W. Mcgraw, John N. Lorenz, Susan E. Wert, Jennifer E. Towne, Richard J. Paul, Jeffrey A. Whitsett, Anil G. Menon

Biology Faculty Publications

Although aquaporin 5 (AQP5) is the major water channel expressed in alveolar type I cells in the lung, its actual role in the lung is a matter of considerable speculation. By using immunohistochemical staining, we show that AQP5 expression in mouse lung is not restricted to type I cells, but is also detected in alveolar type II cells, and in tracheal and bronchial epithelium. Aqp5 knockout (Aqp5−/−) mice were used to analyze AQP5 function in pulmonary physiology. Compared with Aqp5+/+ mice, Aqp5−/− mice show a significantly increased concentration-dependent bronchoconstriction to intravenously administered Ach, as shown by …


The Prevalence Of Human Granulocytic Ehrlichiae In Ixodes Scapularis Ticks In Southeastern Georgia, Heather Anne Merten Jan 2001

The Prevalence Of Human Granulocytic Ehrlichiae In Ixodes Scapularis Ticks In Southeastern Georgia, Heather Anne Merten

College of Graduate Studies: Theses & Dissertations (1964–2006)

Human granulocytic ehrlichiosis (HGE) is a newly emerging, tick-borne zoonosis in North America. The agent that causes HGE is very similar to Ehrlichia phagocytophilia and Ehrlichia equi, but has yet to be classified as a separate species.

This study was carried out in order to determine the prevalence rate of HGE infection in blacklegged ticks (Ixodes scapularis) in insular and mainland sites in southeastern Georgia using nested PCR techniques. Four locations were studied representing 2 barrier islands and 2 mainland sites. We hypothesized that areas that have low levels of human disturbance and are somewhat isolated will …


Density-Dependent Invariance, Dimensionless Life Histories, And The Energy-Equivalence Rule, Eric Charnov, John Haskell, S.K.M. Ernest Jan 2001

Density-Dependent Invariance, Dimensionless Life Histories, And The Energy-Equivalence Rule, Eric Charnov, John Haskell, S.K.M. Ernest

Biology Faculty & Staff Publications

Damuth's energy equivalence rule for mammals is studied in a population dynamic framework.


Rationale For A Focus On Biomphalaria Glabrata, Coen M. Adema, Eric S. Loker, Fred Lewis, Matty Knight Jan 2001

Rationale For A Focus On Biomphalaria Glabrata, Coen M. Adema, Eric S. Loker, Fred Lewis, Matty Knight

Biomphalaria Genome Initiative

No abstract provided.


Acclimation To Hypoxia Increases Survival Time Of Zebrafish, Danio Rerio, During Lethal Hypoxia, Bernard B. Rees, F Sudradjat, J W. Love Jan 2001

Acclimation To Hypoxia Increases Survival Time Of Zebrafish, Danio Rerio, During Lethal Hypoxia, Bernard B. Rees, F Sudradjat, J W. Love

Biological Sciences Faculty Publications

Survivorship of zebrafish, Danio rerio, was measured during lethal hypoxic stress after pretreatment in water at either ambient oxygen or at a lowered, but nonlethal, level of oxygen. Acclimation to nonlethal hypoxia (pO2 @ 15 Torr; ca. 10% air-saturation) for 48 hr significantly extended survival time during more severe hypoxia (pO2 @ 8 Torr; ca. 5% air-saturation) compared to survival of individuals with no prior hypoxic exposure. The magnitude of the acclimation effect depended upon the sex of the fish: hypoxia pretreatment increased the survival times of males by a factor of approximately 9 and that of females by a …


Mean Time To Extinction Of A Metapopulation With An Allee Effect, Chad Brassil Jan 2001

Mean Time To Extinction Of A Metapopulation With An Allee Effect, Chad Brassil

School of Biological Sciences: Faculty Publications

The incorporation of Allee effects into a simple metapopulation extinction model reveals a large non-linear reduction in mean time to extinction with small changes in an Allee limit. The extent of this reduction is dependent on the level of migration in the metapopulation. With small amounts of migration, small changes in the Allee limit result in large changes in the meantime to extinction. With higher levels of migration, the mean time to extinction is not as sensitive to changes in the Allee limit, becoming more similar to the single population case. The metapopulation modeled here is a set of nine …