Sökning: "Predation"

Visar resultat 11 - 15 av 253 avhandlingar innehållade ordet Predation.

  1. 11. 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. 12. Predation as a driver of reproductive isolation - from adaptive divergence to hybrid inviability

    Författare :Varpu Pärssinen; Enhet akvatisk ekologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; reproductive isolation; ecological speciation; predation; adaptive radiation; evolution; behaviour; fish;

    Sammanfattning : Natural selection can play an important role in the origin of new species. When reproductive isolation evolves as a result of ecologically-based divergent natural selection, the process is referred to as ecological speciation. In most organisms, sufficient reproductive isolation is considered to be essential for the establishment of new species. LÄS MER

  4. 13. Direct and indirect effects of fish predation and excretion in aquatic food webs

    Författare :José Luiz Attayde; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; marine biology; Hydrobiology; zooplankton; resilience; predation; phytoplankton; nutrient enrichment; nutrient recycling; interaction strength; herbivory; food webs; food chain; excretion; fish; detritus; detritivory; aquatic ecology; limnology; Marinbiologi; limnologi; akvatisk ekologi; Ecology; Ekologi;

    Sammanfattning : The aim of this thesis was to elucidate the mechanisms by which planktivorous fish can affect planktonic communities in lakes and how they may affect benthic communities through their effects on planktonic communities. In a laboratory experiment, nutrients released by fish increased algal biomass and altered phytoplankton community structure, suggesting that fish can affect phytoplankton by directly releasing nutrients. LÄS MER

  5. 14. On the origin of polymorphism - consequences of competition and predation in heterogeneous environments

    Författare :Jennie Holmér; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; source-sink dynamics; predation; competition; dispersal; polymorphism; evolution; crypsis; adaptive dynamics;

    Sammanfattning : In this thesis, I have studied when an initially monomorphic population can diverge into two morphs in a heterogeneous environment. Evolution is driven by competition for resources or predation. In Paper I, we studied source-sink dynamics during evolution in an environment with two types of resource of different abundance in two habitats. LÄS MER

  7. 15. Shell repair as a response to attempted predation in some Palaeozoic and younger gastropods

    Författare :Anna Lindström; John S. Peel; Jan Ove R. Ebbestad; Euan N. K. Clarkson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Gastropoda; predation; shell morphology; shell repair; Palaeozoic; Geovetenskap; Earth sciences; Geovetenskap;

    Sammanfattning : Traces of unsuccessful predatory attacks can be found in the hard parts of shell-bearing organisms as repaired shell injuries and are often preserved in the fossil record. These repaired shell injuries can help to deduce the relationship between predator and prey in the past. LÄS MER