Global ETD Search
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Showing 1 to 20 of 152 for “"Daphnia"”.
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Mathematical models of daphnia epidemics
… to fascinating dynamics. Our system of study, Daphnia has a lot of interesting and complex features that can be analyzed with precision both biologically and mathematically. By using mathematical models we can study the underlying biological mechanisms that drive and/or inhibit the spread of …
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Competition Between Native and Exotic Daphnia
… introduced exotic cladoceran zooplankter Daphnia lumholtzi offers an excellent opportunity to study the impact of an exotic species on invaded communities. Of particular concern are the possibilities that exotics may displace native taxa and alter trophic interactions. In situ field …
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Genetic variation within the Daphnia pulex genome
<p>Genetic variation within the diploid Daphnia pulex genome was examined using a high quality de novo assembly and shotgun reads from two distinct D. pulex clones. Patterns of variation and divergence at single nucleotides were examined in physical and functional regions of the genome using …
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Thermal Adaptation in <em>Daphnia pulex</em>.
… in freshwater planktonic crustacean <em>Daphnia pulex</em> has been investigated by means of heatshock (35°C) experiments using individuals acclimated to different water temperatures (18, 24, and 28°C). Retention of mobility and survival during the heatshock experiments differed among …
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QSAR studies of surfactant toxicity to Daphnia magna.
… of general formula R-CH(S03"Na +)-C02-R' to Daphnia magna. Due to structural similarities of this class of anionic surfactant to linear alkylbenzene sulphonate (LAS), it was considered that the log P based QSAR originally developed to describe the toxicity of LAS to D. magna (Roberts, 1989) …
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Novel approaches to toxicity testing in Daphnia magna
… as a novel method for toxicity testing using Daphnia magna. Initially I evaluated the potential application of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) based metabolomics for use in regulatory toxicity testing. Subsequently, I aimed to use this approach to …
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Evaluating Chemical Toxicity: A Novel Behavioral Assay Using Daphnia
… A behavioral assay utilizing freely swimming Daphnia pulex was developed to evaluate the sub-lethal chemical effects. Daphnia, a keystone species, are small planktonic invertebrate crustaceans (0.5-5.0mm) in freshwater ecosystems. They are commonly used for aquatic toxicity testing because of …
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Adaptation of an Invasive Cladoceran (Daphnia Lumholtzi) to Temperature
Daphnia lumholtzi, a cladoceran native to the Old World tropics, has successfully invaded lakes and rivers of North America. This invasive species has been successful, in part, due to similarities between native habitats and warm, eutrophic southern lakes and reservoirs, in which summer conditions …
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Acute and chronic effects of selenium on Daphnia pulex
… All data are expressed as selenite-selenium. Daphnia pulex had a 48 hr LC50 of 3.87 mg/l selenium. The 96 hr LC50 and EC50O values for Gambusia affinis and Physa sp. respectively, were 12.56 and 27.08 mg/l selenium. The sublethal effects of 0.2, 0.4, 0.6 and 0.8 mg/1 selenium on survival, …
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Daphnia Diel Vertical Migration and Chemical Cues from Fish Predators
… show a daily pattern of vertical migration. Daphnia undergo daily movements, migrating deeper during the day and rising toward the surface at night. To confirm this movement, field surveys were conducted in Bull Shoals Lake (Missouri–Arkansas) during the summer of 2007. Surveys showed …
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The consequences of predation by Chaoborus americanus on Daphnia pulex
… larva Chaoborus americanus on the crustacean Daphnia pulex were investigated with a combination of laboratory and field assessments. All approaches indicated that Chaoborus inflict a pattern of size-specific mortality on Daphnia that can be well approximated by a Gaussian function. Maximum …
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Evolution of asexuality in Daphnia pulex: Implications of mitochondrial-DNA analysis.
A large scale survey of natural populations of Daphnia pulex was undertaken in the spring of 1985. Seventy seven populations were sampled from southwestern Ontario and central Michigan. Clones were also collected from Churchill, Manitoba. Clonal characteristics were determined by protein …
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Behavioral Response to UVB Differs in Subalpine Populations of Daphnia Melanica
<em>Daphnia </em>are a genus of freshwater zooplankton that inhabit ponds and lakes. They are commonly used as a model organism because they can reproduce clonally and are considered a foundation species in pond ecosystems. <em>Daphnia melanica</em> that inhabit the subalpine ponds of the Olympic …
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Costs and benefits of Daphnia antipredator behavior and consequences on community stability
… I used the planktivorous fish - Chaoborus - Daphnia system. In the laboratory, I found that clonal variance of Daphnia antipredator defenses was high, and that behavioral, morphological, and life-history defenses were uncoupled. To estimate the costs and benefits of antipredator defenses in …
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The effects of diel vertical migration of Daphnia on zooplankton-phytoplankton interactions
… this study was to investigate effects of DVM of Daphnia on phytoplankton dynamics and Daphnia life history parameters in a lake. I conducted field and laboratory experiments in which I compared ‘migration’ with ‘no-migration’ situations. It is generally assumed that phytoplankton communities in …
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