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 19 of 19 for “"latitudinal gradients"”.
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Abyssal polychaete assemblages along latitudinal gradients of productivity in the equatorial Pacific and North Atlantic Oceans
Patterns in polychaete abundance, body size and diversity were investigated at 12 sites between 4300 and 5000 m in the central Pacific and the north-east Atlantic. In the central Pacific, three of the sites (EqPac 0N, 2N and 5N) were observed to lie under high surface productivity regimes, and they …
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Biogeographical Approaches for Studying Species Invasion
… range. I also examined the evolution of latitudinal gradients in native and invasive genotypes of P. australis in relation to plant-herbivore interactions in North America. Common garden experiments revealed that the native and invasive genotypes of P. australis have evolved latitudinal …
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Early Life History Stage Dynamics Across the Elevational Ranges of Andean Trees
… ranges are predicted to occur along elevational gradients, particularly with respect to temperature, as latitudinal gradients in temperature are shallow or nonexistent. To move upslope species will have to disperse to new areas and contend with novel combinations of biotic and abiotic factors …
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Paleoclimate and mammal paleocology during the paleocene of North America: insights from stable isotopes.
… from well-structured patterns that exist today. Latitudinal gradients in Paleocene mammal species richness and body size differ from the patterns observed today among extant mammals. Differences between Paleocene and modern biogeographic patterns could be a function of unique Paleocene faunas …
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Palaeoenvironmental and palaeogeographic reconstruction of the Tequixquiac Basin, Central Eastern Mexico: Mid to late Pleistocene environments
… in the mean position of the ITCZ related to SST, latitudinal gradients, atmospheric surface pressure gradients, the extent of Northern Hemisphere land and sea ice cover, and oceanic circulation patterns. Fluctuations in the TOC content of sediments are thought to be related to El Niño-like (dry) …
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Latitudinal Variation in Thermal Tolerance and Preference of <i>Fundulus notatus</i> and <i>F. olivaceus</i>: Implications for Temperature Mediated Reproductive Isolation
… environments. Variable temperature regimes along latitudinal gradients might be responsible for adaptive differences in thermal biologies among populations. I examined whether latitude reflects intra- and interspecific differences in thermal preference and tolerance across a gradient of …
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The macroecological distribution of avian functional diversity: environment, extinction risk and protected area coverage
… macroecological distribution of FD. Old World latitudinal gradients of FD are found to reflect contemporary environment, particularly energy availability. Analyses restricted to sedentary species reveal the importance of migration (e.g. for breeding assemblages a positive association with …
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Environmental granularity, rivers and climate history as shaping factors for species' distribution and diversity patterns
… been explained by: environmental heterogeneity, latitudinal gradients, system energy, and biogeographic history among others. Several attempts have been made to replicate biodiversity using spatially and environmentally explicit null models with different degrees of success, but they do not …
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Phylogenetics of North American Psoraleeae (Leguminosae): Rates and Dates in a Recent, Rapid Radiation
… Rapoport's rule of species-richness following latitudinal gradients. Finally, estimated phylogenies are used to investigate divergence dates, nucleotide substitution rates, diversification rates, and the impact of climate change, past and present, on diversification of NAm Psoraleeae. Results …
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Biological and Ecological Trait Associations and Analysis of Spatial and Intraspecific Variation in Fish Traits
… large-scale life history trait variability along latitudinal gradients for twelve widely distributed fish species, including directionality of trait variation, and hypothesizing how optimal traits change with large-scale environmental factors. Strong positive and negative patterns found include …
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Investigating Causal Relationships between Global Change and Insect Interaction Networks: Insights into Dietary Specialization, Interaction Diversity, and Disturbances
… quantifying effects of biotic and abiotic gradients on dietary specialization, interaction diversity, and related attributes of arthropod communities. My focus on how specialization varies across gradients and is affected by global change addressed a classic hypothesis, the …
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Geographic variation in size at age of the coral reef fish, Thalassoma lunare (family: Labridae) : a contribution to life history theory.
… ranges, in particular those involving a latitudinal or altitudinal gradient. Temperature is likely to be a particularly important factor influencing life histories at these scales, especially for those animals that rely on external sources for body heat. Numerous studies of terrestrial …
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Coccolithophores in high latitude and Polar regions: Relationships between community composition, calcification and environmental factors
… Arctic Ocean and in the Southern Ocean. Large gradients in carbonate chemistry and other variables provided insights into coccolithophore response to concurrent changes in the future ocean. Freshwater inputs and biological processes were driving the carbonate chemistry changes in the surface …
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Coral adaptations across ecological and evolutionary scales
… distributions of conditions across large (e.g., latitudinal gradients) and small (e.g., different depths) scales. Populations that exist across these environments might be adapted to local conditions and exhibit genetic divergence between habitats, sometimes to the point of becoming different …
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Climate control on plant performance across an Andean altitudinal gradient
… challenges of biology. The use of altitudinal gradients as 'natural experiments' to test the influence of climate on species distributions and performance has a long history in ecology and biogeography. This approach is a powerful way to gain insight into how species and ecosystems respond to …
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An examination of temporal trends, regional variation, and habitat-type differences in site-level Floristic Quality, and their implications for the use of Floristic Quality Assessment
… than wetlands, which showed a weak, quadratic latitudinal relationship. Forests were the only habitat that varied in richness, exhibiting a weak decline to the north. Temporal Floristic Quality trends were compared using a 50-year, old-field succession study. Values in all fields followed the …
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Toward Ecological Holism: Discerning Pattern, Process and Scale Across the Productivity Landscape
… Increases in biomass were associated with latitudinal gradients and seasonal forcing at the regional scale, and more closely associated with topographic and edaphic characteristics at the forest-stand scale. My analyses indicated that we can accurately predict which forests will be less …
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Biodiversity and Biogeography of Amphipod Crustaceans
… I determined the regions of endemicity and latitudinal gradients for three measures of diversity (alpha, gamma, and beta diversity). The analysis of the spatial patterns of richness and endemicity, based on over 400,000 distribution records of 4,876 amphipod species, identified 12 regions of …