Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 18 of 18 for “"species concept"”.
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Hybridization Between the Watersnakes <i>Nerodia sipedon</i> and <i>Nerodia fasciata,</i> in the Carolinas: A Morphological and Molecular Approach
… was successful in separating both taxa. Species-specific nuclear markers, identified by the AFLP (Amplified Fragment Length Polymorphism) technique were nearly fixed and served as diagnostic markers. They revealed extensive introgression between the two species not recognizable …
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Isozyme patterns of selected isolates of Pholiota in the stirps "Adiposa"
The species concept in Pholiota, stirp Adiposa Smith and Hesler, has been investigated by applying electrophoretic techniques to isolates that have previously been examined for their morphology and mutual mating compatibility. Crude protein extracts of soluble proteins from mycelium grown in liquid …
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Extending Regulatory Network Modeling with Multistate Species
… any automation or aid. Using the multistate-species concept we can reduce the number of reactions needed to represent certain systems and thus, lessen the cognitive load on modelers. A multistate species is an entity with a defined range for state variables, which refers to a group of …
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EVALUATION OF POTENTIAL PRE-MATING REPRODUCTIVE ISOLATION IN TIGER BEETLES (CARABIDAE: CICINDELINAE)
The biological species concept depends on mechanisms isolating reproduction to taxonomically define a species and to explain the disadvantages, and subsequent lack, of hybridization. In co-occurring tiger beetles (Carabidae: Cicindelinae), these between-species barriers are not readily apparent. To …
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The Evolution of the Glenoid Region in the Hominidae: Implications for Hominid Phylogenetics
… problematic. Moreover, because individual species of Homo exhibit a wide range of morphological variation, with considerable overlap between species, it is not possible to reject or accept the multiple species hypotheses for either H. habilis or H. erectus. In fact, the recent trend of …
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Systematics and Evolution of the Californian Trapdoor Spider Genus Aptostichus Simon (Araneae: Mygalomorphae: Euctenizidae)
… genus Aptostichus Simon, 1890 describes 28 species, 25 of which are newly described: A. atomus, A. improbulus, A. insulanus, A. icenoglei, A. ebriosus, A. muiri, A. cahuillus, A. luiseni, A. serranos, A. calientus, A. chemehuevi, A. shoshonei, A. pauitei, A. tipai, A. cochesensis, A. …
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Molecular phylogeny of Melanospora and Diaporthales, and population genetics of dogwood anthracnose fungus
… Discula destructiva and four other Discula species were derived from within Diaporthales according to the SSU and LSU nrDNA and RPB2 phylogenies. There were three clades in the LSU nrDNA phylogeny. The five Discula species were in one of the clades but they were not monophyletic. This …
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Evolutionary dynamics of speciation and extinction
… dictates offspring placement, and it defines a species based on reproductive isolation (known as the biological species concept), while a globally enforced death process ensues within each generation. This system is shown to exhibit nonequilibrium, continuous phase transitions as a function of …
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Phylogeography of the Night Lizard, Xantusia henshawi, from Southern California
… little morphological variation is seen in this species over a variety of habitats throughout its range, from elevations near sea level to approximately 2000 meters, and from Mediterranean habitats near the Pacific coast to arid desert habitat in the Colorado Desert of California. One exception …
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Identidade e alocação taxonômica de duas formas simpátridas de Oxymycterus (Rodentia: Sigmodontinae) do sudeste do Brasil: uma avaliação de hipóteses sobre a diversidade do gênero
… difficulties in the morphological definition of species and to the controversies on the application of a biological species concept to alopatric samples. Therefore, several authors have considered the species described from Brazil as synonyms of O. rufus (Fischer, 181 4), including O. dasytrichus …
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Shifts in Myxomycete Community Structure in Selected Microhabitats Across Nutrient Treatments in a Lowland Tropical Forest of Panama
… with two major contributions. Identifying species is a fundamental step toward characterizing the diversity of a community. Given the unique challenge of identifying species of myxomycetes imposed by their unique biology, this dissertation begins in chapter two with a review of the …
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Molecular Systematics of <i>Isoëtes</i> (Isoëtaceae) in Eastern North America
… 200 total taxa, about half are in a clade of species mostly occurring in North and South America. Eastern North America accounts for 22% of global taxonomic diversity, containing 32 fertile taxa and 16 named hybrids. This taxonomic diversity is built upon relatively little morphological …
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Emiliania huxleyi and climate change: a genetic and biogeographic investigation of bloom dynamics for a key phytoplankton species in the global carbon cycle
… of genetic variability within the E. huxleyi species concept, which may translate into phenotypic plasticity, such as differing levels of viral resistance. In the SO, the spatial and temporal biogeography of the three most numerous mineralizing nannoplankton groups, the coccolithophore E. …
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Integrative approach to discovering species diversity within the Mediterranean group of the Bemisia tabaci complex
Bemisia tabaci is a complex of cryptic whitefly species, which includes some of the world’s most damaging agricultural pests. The Mediterranean (MED) putative species is globally invasive and its populations are often resistant to insecticides. The intra-species genetic variability identified in …
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Biodiversity of phytoparasitic nematodes associated with Musaceae and fruit crops in Colombia
… on two composition components of biodiversity (species and genes) as a contribution to the analyses of biodiversity of economically important plant-parasitic nematodes in Colombia. Samples were taken from 16 different regions of the country. Identification, characterization, and description of …
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Advancing the use of evolutionary considerations in spatial conservation planning
… planning remain rare, with metrics such as species richness (which ignore differences in evolutionary distinctiveness between species) more often used. This work aims to address this by focusing on the inclusion of phylogenetic diversity (PD), which measures evolutionary diversity by summing …
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Genome evolutionary studies of the Salmonella enterica serovars: implications for the dynamics of horizontal gene transfer, the pangenome concept, and bacterial and archaeal taxonomy
… in microbial taxonomy, including as to if a species concept is even possible for microbes. Gene loss also plays a significant role in the evolution of microbial genomes. If free-living and facultative organisms are constantly subject to gene gain via horizontal gene transfer, then their …
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Evolution of the Neckeraceae (Bryopsida)
… mosses comprises approximately 5000 species, which corresponds to about half of all mosses. The pleurocarpous mosses (i.e. “the Core Pleurocarps”) form a monophylum, which consists typically of perennial mosses with creeping stems and abundant lateral branches. In pleurocarpous mosses …