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Showing result 21 - 25 of 331 swedish dissertations matching the above criteria.

  2. 21. Food hoarding: Memory and social conditions - an evolutionary approach

    Author : Ken Lundborg; Biologiska institutionen; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Djurekologi; Animal ecology; Corvidae; Paridae; dominance rank; memory; food hoarding; foraging; hippocampus; birds; behavioural ecology;

    Abstract : Food hoarding is a widespread behavior among a large number of animals, and it exists in several different varieties, all of them used by the animals as a method of having a steady supply of food during periods of low food abundance such as the winter. This thesis concentrates mainly on two aspects of scatter food hoarding behavior, using small birds as study and model animals. READ MORE

  4. 22. Biology of Borrelia garinii Spirochetes

    Author : Pär Comstedt; Sven Bergström; Wolfram R. Zückert; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Borrelia garinii; Lyme borreliosis; birds; migration; reservoir host; complement; Ixodes ricinus; Europe; Asia; infection cycle; Molecular biology; Molekylärbiologi;

    Abstract : Lyme borreliosis is a tick-transmitted infectious disease. The causative agents are spiral-shaped bacteria and the most common sign of infection is a skin rash at the site of the tick bite. READ MORE

  5. 23. Bird orientation: external cues and ecological factors

    Author : Johan Bäckman; Evolutionär ekologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; tracking radar; Emlen funnel.; Animal ecology; Djurekologi; oscillatory orientation; roosting flight; scatter; concentration; heading; cue calibration; light dependent; magnetoreception; subcutaneous fat stores; body condition; energetics; geomagnetic field; visual cues; orientation; birds; migration;

    Abstract : Birds are generally capable of accurate orientation. In this thesis I present studies about the external cues and the ecological factors that influences bird orientation. A multitude of environmental cues are used to select and maintain a proper direction. READ MORE

  6. 24. The tempo and mode of evolution : a neontological reappraisal

    Author : Melanie Monroe; Folmer Bokma; Pär Ingvarsson; Mikael Fortelius; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; birds; extinction; macroevolution; mammals; microevolution; punctuated equilibrium; speciation;

    Abstract : The theory of “punctuated equilibrium” suggests that species evolve rapidly during or immediately upon speciation, “punctuating” long periods of little or no morphological evolution. Here I confirm that body size differences within clades of birds and mammals are best explained using a model of punctuated evolution. READ MORE

  7. 25. The exploration and evolution of the avian genomic dark matter

    Author : Valentina Peona; Alexander Suh; Hanna Johannesson; Rachel O'Neill; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; evolutionary genomics; genome assembly; sex chromosomes; birds; satellite DNA; transposable elements; endogenous retroviruses; Biology with specialization in Systematics; Biologi med inriktning mot systematik;

    Abstract : The development and improvement of genome sequencing technologies in the last decade revolutionised the entire field of biology with genome assemblies of virtually any organism. Despite this tremendous progress, complex genomic regions are systematically missing from genome assemblies and form the so-called "genomic dark matter". READ MORE