Sökning: "naturvetenskapliga teorier"

Visar resultat 1 - 5 av 11 avhandlingar innehållade orden naturvetenskapliga teorier.

1. 1. The balance between sex and asex: evolutionary genetic studies of reproductive variation in Allium vineale

   Författare :Alf Ceplitis; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ontogeny; growth animal ; Allium vineale; Development biology; evolution; sexual reproduction; reproductive systems; embryology; Utvecklingsbiologi; ontogeni; embryologi; Genetics; cytogenetics; Genetik; cytogenetik;

   Sammanfattning : Evolutionary theory predicts a disadvantage to sexual reproduction. This manifests itself either by the higher growth rate of asexual females in a dioecious species, or by the higher transmission rate of a gene conferring asexual female function to its carriers in a hermaphrodite species. LÄS MER

3. 2. Magnetic map sense in animals: effects of geographic and magnetic displacements

   Författare :Jannika Boström; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Oenanthe oenanthe; skylight polarization; geomagnetic map; geomagnetic field; endogenous migration programme; migratory fuelling; orientation; animal navigation;

   Sammanfattning : Migration research is a large and diverse field and in my thesis I have focused on the impact of geomagnetic cues on animal orientation, navigation and migratory fuelling. Several animal species from widely different taxa possess the ability to sense and make use of geomagnetic information during migratory or homing events. LÄS MER

4. 3. On the role of migration for the distribution of arctic birds - a circumpolar perspective

   Författare :Sara Henningsson; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; bird migration; broad-scale distributions; geographic breeding range; geography of migration; non-breeding range; barriers to migration; Arctic birds; evolution of migration routes;

   Sammanfattning : Flexibility as well as constraints to the evolution of migration routes has the possibility of affecting large-scale patterns of geographical ranges of animals both by facilitating, but sometimes restricting, accessibility to and colonization of new regions. This dissertation concerns the broad-scale effects migration has on the distributional patterns of birds in the Arctic. LÄS MER

5. 4. Community and food web assembly on virgin habitat islands - The nunatak saga

   Författare :Maria Ingimarsdottir; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; allochthonous material; arthropods; community assembly; corridor; dispersal; Iceland; metacommunity; nunataks; primary succession; stable isotopes.;

   Sammanfattning : The classical view of primary community assembly is that colonisation by plants is essential before invertebrates can establish. It has been recognised, however, that invertebrates can establish before plants, and that they may be important in the first steps of community assembly. LÄS MER

7. 5. Quantitative Genetics and Genome Structure in a Wild Population: the Use of a Great Reed Warbler Pedigree

   Författare :Mikael Åkesson; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; genome mapping ; AFLP; microsatellite; synteny; heterochiasmy; recombination; chicken; great reed warbler ; bird; Genetics; cytogenetics; Genetik; cytogenetik; Animal ecology; trait correlation ; Djurekologi; animal model ; selection; Djurs anatomi och morfologi; animal morphology; Animal anatomy; heritability;

   Sammanfattning : Long-term studies of birds play an important role in the understanding of quantitative traits in natural populations. The relative ease by which individual birds can be monitored and caught in the wild enable us collect detailed information from individuals throughout their life time, sometimes from several generations in a population. LÄS MER