Sökning: "natural selection"

Visar resultat 26 - 30 av 1236 avhandlingar innehållade orden natural selection.

1. 26. The Interplay Between Selection And Constraints On Adaptive Divergence And Phenotypic Evolution

   Författare :Fabrice Eroukhmanoff; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Selection; Constraints; Adaptive Divergence; G-matrix; Gene Flow.; Speciation;

   Sammanfattning : Under natural or sexual selection, individuals with advantageous traits or combinations of traits will be more successful than their peers at surviving and/or reproducing. Provided these traits are heritable, meaning that they have a genetic basis, the traits combinations which are selected for, will increase in frequency in the population. LÄS MER

3. 27. Genetic response to pollution in sticklebacks; natural selection in the wild

   Författare :Emma Lind; Mats Grahn; Marjorie Oleksiak; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Population genomics; genome scan; divergent selection; Gasterosteus aculeatus; Baltic Sea; pollution; funktionell zoomorfologi; Functional Zoomorphology;

   Sammanfattning : The last century, humans have been altering almost all natural environments at an accelerating rate, including the Baltic Sea that has highly eutrophicated areas and many coastal industries such as Pulp-mills. For animals living in a habitat that changes there are basically two alternatives, either to cope with the change or become locally extinct. LÄS MER

4. 28. Detecting Sex and Selection in Ancient Cattle Remains Using Single Nucleotide Polymorphisms

   Författare :Emma M Svensson; Anders Götherström; Juha Kantanen; Uppsala universitet; []
   Nyckelord :HUMANIORA; HUMANITIES; NATURVETENSKAP; NATURAL SCIENCES; aurochs; cattle; ancient DNA; SNP; pyrosequencing; selection; Bos taurus; Historical osteology; Historisk osteologi; Genetics; Genetik; Biology with specialization in Evolutionary Genetics; Biologi med inriktning mot evolutionär genetik;

   Sammanfattning : All contemporary taurine cattle originated some 10,000 years ago when their wild ancestor, the aurochs, was domesticated in the Near East. Although the aurochs was widespread also in Europe, there is no evidence for a local domestication. The aurochs has been extinct since 1627 and therefore little is known about its biology. LÄS MER

5. 29. Life History and Tolerance and Resistance against Herbivores in Natural Populations of Arabidopsis thaliana

   Författare :Reiko Akiyama; Jon Ågren; Arjen Biere; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Arabidopsis thaliana; life history evolution; flowering time; germination; phenology; plant-herbivore interactions; natural selection; tolerance to leaf damage; resistance to herbivory; Plutella xylostella; Mamestra brassicae; Biology with specialization in Ecological Botany; Biologi med inriktning mot ekologisk botanik;

   Sammanfattning : In this thesis, I combined observational studies with field and greenhouse experiments to examine selection on life history traits and variation in tolerance and resistance against herbivores in natural populations of the annual herb Arabidopsis thaliana in its native range. I investigated (1) phenotypic selection on flowering time and plant size, (2) the effects of timing of germination on plant fitness, (3) the effect of leaf damage on seed production, and (4) correlations between resistance against a specialist and a generalist insect herbivore. LÄS MER

7. 30. In vitro selection of DNA sequences with extreme affinities for the nucleosome core particle

   Författare :Hui Cao; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TATA-tetrad; TGGA-repeat; nucleosome; selection;

   Sammanfattning : .... LÄS MER