Sökning: "predation pressure"

Visar resultat 6 - 10 av 30 avhandlingar innehållade orden predation pressure.

  1. 6. 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

  3. 7. Spatial and temporal population dynamics in the mountain tundra – mesopredator and prey

    Författare :Rasmus Erlandsson; Anders Angerbjörn; Dennis Murray; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; population dynamics; cyclic; mountain tundra; arctic fox; Norwegian lemming; small rodents; mesopredator; predation; survival; reproduction; zoologisk ekologi; Animal Ecology;

    Sammanfattning : It is well known that competition, predation and fluctuating food resources can have strong effect on individual fitness and population dynamics. The complexity of natural systems can make it complicate to disentangle those processes, but environments with relatively simple food webs, and strong cyclic population dynamics offer contrasting conditions resembling experimental treatments. LÄS MER

  4. 8. Phenotypic plasticity and the evolution of an inducible morphological defence in crucian carp

    Författare :Lars Pettersson; Biodiversitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Animal ecology; Benefits; Costs; Predation; Chemical cues; Fish; Djurekologi;

    Sammanfattning : In this thesis, I have investigated factors (cues, benefits, and costs) affecting the evolution of an inducible morphological defence in crucian carp (Carassius carassius). Inducible defences are favoured over permanent defences when prey have reliable cues to detect predators, when defences are effective but costly, and when predation pressure is variable and unpredictable, but sometimes strong. LÄS MER

  5. 9. The role of young-of-the-year fish in lake ecosystems

    Författare :Pia Romare; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Hydrobiology; Rutilus rutilus; Perca fluviatilis; diet-dependent growth; density dependent growth; behavioural cascade; 0 fish behaviour; horizontal echo sounding; biomanipulation; trophic cascade; predation pressure; young-of-the-year fish; trophic interactions; marine biology; aquatic ecology; limnology; Marinbiologi; limnologi; akvatisk ekologi; Ecology; Ekologi;

    Sammanfattning : Food chain theory is based on consumption; that is, presupposing that the only important interaction between organisms is that they actually meet in an unstructured environment and that one of them is consumed. Recently, studies, including biomanipulation projects, have indicated that trophic interactions are more complex than predicted by food chain theory. LÄS MER

  7. 10. Temporal and spatial variation in predation on roe deer fawns

    Författare :Jonas Nordström; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES;

    Sammanfattning : This thesis deals with variation in mortality of roe deer fawns, over time and in space, caused by red fox and Eurasian lynx predation in a boreal landscape. The thesis considers historic and recent effects of vole population dynamics on red fox predation on roe deer fawns, using long term time series from Grimsö Wildlife Research Area. LÄS MER