Sökning: "invertebrate predators"

Visar resultat 1 - 5 av 11 avhandlingar innehållade orden invertebrate predators.

  1. 1. The importance of predation in benthic stream communities

    Författare :Jonas Dahl; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Ekologi; Ecology; invertebrate predators; vertebrate predators; Predation; streams;

    Sammanfattning : There has been considerable debate whether or not predators has any significant effects on prey densities in streams. This thesis examines the importance of predation in stream communities. I have conducted both field and laboratory studies where I have studied how both vertebrate and invertebrate predators affects benthic prey. LÄS MER

  3. 2. Morphological antipredator adaptations in water fleas

    Författare :Hans Lord; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Body drag; Daphnia cristata; Reynolds number; viscosity; zooplankton; Bosmina; swimming velocity; cyclomorphosis; sexual dimorphism; head area; helmet angle; trophic condition; allometry; invertebrate predator; fish;

    Sammanfattning : Some Bosmina and Daphnia species have the ability to develop extreme morphological antipredator defences, such as long antennules, high carapaces and helmets. The relative sizes of these plastic traits may differ substantially between populations, and also between individuals within a population, between sexes and during ontogeny. LÄS MER

  4. 3. Causes and consequences of niche differentiation between color morphs of pygmy grasshoppers

    Författare :Einat Karpestam; Anders Forsman; Birgitta Tullberg; Linnéuniversitetet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; color polymorphism; visual predators; Tetrix subulata; differential habitat use; niche; thermoregulation; feeding preferences; stable isotopes; Evolutionary Biology; Evolutionsbiologi;

    Sammanfattning : In this thesis, I used the color polymorphic pygmy grasshopper, Tetrix subulata, as a model system in order to investigate the degree of niche differentiation between alternative color morphs that are present within a single population. First, I hypothesized that individuals belonging to different color morphs differ in their innate food preference due to somewhat dissimilar physiology, and in their actual food consumption due in part to differential habitat use. LÄS MER

  5. 4. The prey perspective - behaviour and appearance in a world of predators

    Författare :Johan Ahlgren; Enhet akvatisk ekologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Local adaptation; predator regime; phenotypic plasticity; inducible defence; mortality; animal personality; predator; trait-compensation;

    Sammanfattning : The varieties of prey phenotypes that have been revealed in nature are vast and many of these phenotypes are the result of the selective force that predators have had on prey traits in the past. Even within species and populations we see variations due to both differences in the selection forces they live under but also due to individual trait variation. LÄS MER

  7. 5. Interactions between gray-sided voles (Clethrionomys rufocanus) and vegetation in the Fennoscandian tundra

    Författare :Jonas Dahlgren; Lauri Oksanen; Johan Olofsson; John Terborgh; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; gray-sided voles; tundra vegetation; trophic cascades; plant-herbivore interactions; bilberry; plant communities; herbivory; plant resistance; Terrestrial ecology; Terrestisk ekologi;

    Sammanfattning : I have, in this thesis, studied the interactions between gray-sided voles (Clethrionomys rufocanus) and tundra vegetation, on islands in, and mainland sites close to the lake Iešjávri, in northern Norway. As isolated islands are virtually free of predation, I have been able to compare plant-herbivore interactions in the presence and absence of predators. LÄS MER