Search for dissertations about: "predation limitation"

Showing result 1 - 5 of 12 swedish dissertations containing the words predation limitation.

2. 1. Mechanisms structuring the pelagic microbial food web : Importance of resource and predation

   Author : Kristina Samuelsson; Agneta Andersson; Christiane Lancelot; Umeå universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Ecology; pelagic microbial food web; bacteria; flagellates; ciliates; phytoplankton; mixotrophy; nutrient status; predation limitation; resource limitation; Baltic Sea; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

   Abstract : Temporal and spatial variations of pelagic microorganisms in the northern Baltic Sea were studied, as well as factors influencing their abundance and growth rates. Three main questions were asked 1) How does increased productivity influence the structure of the microbial food web? 2) Does predation limitation vary between trophic levels? 3) What is the relative importance of resource and predation limitation at different trophic levels?A field study in the northern Baltic Sea showed that dominating protozoa, flagellates and ciliates, increased with increasing primary productivity from north to south. READ MORE

4. 2. Pelagic microorganisms in the northern Baltic Sea : Ecology, diversity and food web dynamics

   Author : Johnny Berglund; Agneta Andersson; Ramon Massana; Umeå universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; resource limitation; predation limitation; microbial food web; heterotrophic microorganisms; nanoflagellates; ciliates; protists; resource heterogeneity; chrysomonads; chrysophytes; group-specific PCR-DGGE primers; Baltic Sea; Marine ecology; Marin ekologi;

   Abstract : Heterotrophic microorganisms are important for the flow of carbon and nutrients in the sea. Bacteria, nanoflagellates and ciliates are relevant components of the pelagic food web. In order to be able to predict the outcome of e.g. READ MORE

5. 3. Plant-animal interactions and seed output of two insectpollinated herbs

   Author : Anna R. Waites; Umeå universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; plant reproduction; pollen limitation; pollinator behaviour; heterostyly; seed predation; Lythrum salicaria; Pedicularis palustris; stigma receptivity; self-pollen; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

   Abstract : I combined comparative and experimental studies in the field and in the greenhouse to examine factors influencing reproductive success in two insect-pollinated herbs, the tristylous, selfincompatible perennial Lythrum salicaria and the self-compatible, biennial Pedicularis palustris. More specifically, I explored (i) the effects of plant population characteristics on the intensity and outcome of interactions with pollinators and seed predators, (ii) whether flower morphology affects duration of stigma receptivity, and (iii) whether damage-induced reduction in floral display reduces pollinator visitation and increases pollen limitation. READ MORE

6. 4. Body Size Evolution in Butterflies

   Author : David Berger; Karl Gotthard; Wolf Blanckenhorn; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Body size evolution; age- and size at maturity; life history theory; fecundity; predation risk; juvenile growth rate; Lepidoptera; Biology; Biologi; zoologisk ekologi; Animal Ecology;

   Abstract : Life history research deals with the scheme of resource partitioning to a wide spectra of processes and the trade-offs shaping these events. One of the most fundamental life history trade-offs is the one of at which age- and size an organism should start to reproduce; reaching a large size at maturity is often advantageous in terms of high adult survival and reproductive potential, while to attain a larger size the organisms must prolong juvenile development which is assumed costly in terms of mortality. READ MORE

7. 5. Survival patterns and density-dependent processes in breeding mallards Anas platyrhynchos

   Author : Gunnar Gunnarsson; Kjell Sjöberg; Johan Elmberg; Per Lundberg; Robert Clark; Högskolan Kristianstad; []
   Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; broods; dabbling ducks; density dependence; ducklings; experiments; models; mortality; nest predation; regulation; survival; Terrestrial ecology; Terrestrisk ekologi;

   Abstract : Measuring and assessing vital rates such as births and deaths are prerequisites for understanding population dynamics. Vital rates may be affected by the density of individuals, even though the importance of density dependence on population dynamics has been debated for a long time. READ MORE