Sökning: "Lennart Persson"

Visar resultat 21 - 25 av 28 avhandlingar innehållade orden Lennart Persson.

  1. 21. Effects of size-dependent predation and competition on population and community dynamics

    Författare :Karin Nilsson; Lennart Persson; Volker Rudolf; Umeå universitet; []
    Nyckelord :size-structure; cannibalism; resource competition; predation; emergent facilitation; population regulation; population dynamics; overcompensation; density-dependence; cycles; zooekologi; Animal Ecology;

    Sammanfattning : Most animals grow substantially during their lifetime and change in competitive ability, predatory capacity and their susceptibility to predation as they grow. This thesis addresses the implications of this on regulation and dynamics within populations as well as between population interactions. LÄS MER

  3. 22. Ontogenetic bottlenecks : effects on intraguild predation systems and ecosystem efficiency

    Författare :Birte Reichstein; Lennart Persson; André M. De Roos; Priyanga Amarasekare; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; mixed interactions; cannibalism; life-history omnivory; ontogenetic niche shift; biomass overcompensation; biomass production; ontogenetic asymmetry; indirect effects; biology; biologi; zooekologi; Animal Ecology;

    Sammanfattning : Size-dependent differences between individuals in size-structured organisms have fundamental effect on population and community dynamics. Intraguild predation (IGP) is one specifically interesting constellation that often arises when two size-structured populations interact. LÄS MER

  4. 23. Alternative Stable States in Size-Structured Communities : Patterns, Processes, and Mechanisms

    Författare :Arne Schröder; Lennart Persson; André M. de Roos; Tim Benton; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; biomass overcompensation; Chaoborus; emergent Allee effect; Heterandria formosa; juvenile recruitment bottlenecks; ontogenetic niche shifts; Poecilia reticulata; Biology; Biologi;

    Sammanfattning : Alternative stable states have been, based on theoretical findings, predicted to be common in ecological systems. Empirical data from a number of laboratory and natural studies strongly suggest that alternative stable states also occur in real populations, communities and ecosystems. LÄS MER

  5. 24. Ecology and Evolution of Adaptive Morphological Variation in Fish Populations

    Författare :Richard Svanbäck; Peter Eklöv; Lennart Persson; Beren Robinson; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; competition; functional morphology; individual specialization; inter-individual variation; intra-population variation; morphological variation; ontogeny; Perca fluviatilis; perch; phenotypic plasticity; predation; trade-offs; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

    Sammanfattning : The work in this thesis deals with the ecology and evolution of adaptive individual variation. Ecologists have long used niche theory to describe the ecology of a species as a whole, treating conspecific individuals as ecological equivalent. LÄS MER

  7. 25. Malignancies in Sweden after the Chernobyl accident in 1986

    Författare :Martin Tondel; Bodil Persson; Lennart Hardell; Bengt Järvholm; Linköpings universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Epidemiology; Environmental; Chernobyl; ionising radiation; geographical information systems GIS; 8-OHdG; Malignancies; Low dose; Dose-response; Latency; Causalty; Epidemiology; Epidemiologi;

    Sammanfattning : On 26 April 1986 an accident occurred in the Chernobyl nuclear power plant resulting in the release of large amount of radionuclides. Almost five percent of the total released caesium-137 was deposited in Sweden. The incidence of malignancies in the most affected counties in Sweden was investigated in three epidemiological studies. LÄS MER