Sökning: "cohort competition"

Visar resultat 1 - 5 av 13 avhandlingar innehållade orden cohort competition.

  1. 1. Age-class interactions in Atlantic salmon and brown trout: Effects on habitat use and performance

    Författare :Rasmus Kaspersson; Göteborgs universitet; []
    Nyckelord :competition; inter-cohort; density-dependence; growth; habitat; Salmo trutta; Salmo salar; salmon; trout;

    Sammanfattning : This thesis investigates the underlying mechanisms and the density-regulatory effects of age-class interactions, using juvenile Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta L.) as study species. LÄS MER

  3. 2. Ontogenetic scaling and the development of within-cohort size structure

    Författare :Magnus Huss; Lennart Persson; Pär Byström; David Post; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; cannibalism; competition; density-dependence; resource feedbacks; hatching; growth; ontogenetic niche shifts; Perca fluviatilis; size variation; larval fish; Freshwater ecology; Limnisk ekologi; zooekologi; Animal Ecology;

    Sammanfattning : It is increasingly recognized that individuals of the same species differ from each other and influence and respond to their environment in unique ways. This thesis deals with size variation among individuals that not only are of the same species but also of similar age. LÄS MER

  4. 3. Criterion-referenced measurement for educational evaluation and selection

    Författare :Christina Wikström; Widar Henriksson; Roger Murphy; Umeå universitet; []
    Nyckelord :Assessment; Competition; Criterion-referenced; Education; Evaluation; Grading; Grade inflation; Measurement; Selection; Validity; Beteendevetenskapliga mätningar; pedagogik; Education;

    Sammanfattning : In recent years, Sweden has adopted a criterion-referenced grading system, where the grade outcome is used for several purposes, but foremost for educational evaluation on student- and school levels as well as for selection to higher education. This thesis investigates the consequences of using criterion-referenced measurement for both educational evaluation and selection purposes. LÄS MER

  5. 4. Climate change impacts on production and dynamics of fish populations

    Författare :Per Hedström; Pär Byström; Jan Karlsson; Peter Eklöv; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Temperature; terrestrial dissolved organic carbon; light extinction; GPP; recruitment; winter mortality; metabolism; cohort competition; fish production; fish biomass;

    Sammanfattning : Ongoing climate change is predicted to increase water temperatures and export of terrestrial dissolved matter (TDOM) to aquatic ecosystems influencing ecosystem productivity, food web dynamics and production of top consumers. Ecosystem productivity is mainly determined by the rates of primary production (GPP) in turn controlled by nutrients, light availability and temperature, while temperature alone affect vital rates like consumption and metabolic rates and maintenance requirements of consumers. LÄS MER

  7. 5. 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