Sökning: "trait variation"

Visar resultat 11 - 15 av 141 avhandlingar innehållade orden trait variation.

1. 11. Population genomic analyses of regulatory variation and selection in Brassicaceae species

   Författare :Robert Horvath; Tanja Slotte; Peter Hambäck; Douglas G. Scofield; Matthew Webster; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Capsella grandiflora; Arabidopsis thaliana; Arabidopsis lyrata; natural selection; gene expression variation; DNA and gene body methylation; transposable elements; DNA accessibility; gene expression noise; epigenetic silencing; linked selection; ekologi och evolution; Ecology and Evolution;

   Sammanfattning : The impact of selection on regulatory variation and the contribution of regulatory changes to phenotypic variation has long been debated in evolutionary genetics. Because cis-regulatory elements such as promoters and enhancers can be difficult to identify, it has been more challenging to quantify the impact of selection on variation in cis-regulatory regions than in protein-coding regions. LÄS MER

3. 12. Plant polyploidy and interactions with insect herbivores

   Författare :Leena Arvanitis; Johan Ehrlén; Christer Wiklund; John N. Thompson; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; diversicifation; herbivory; host plant preference; plant galls; plant-insect interactions; plant polyploidy; selection; spatial variation; trait-fitness relationship; Terrestrial ecology; Terrestisk ekologi; Plant Ecology; växtekologi;

   Sammanfattning : Polyploidization has been suggested to be a common mechanism for plant speciation. Polyploidy is associated with changes in plant traits and altered habitat preference. LÄS MER

4. 13. Pollinator-mediated selection and the evolution of floral traits in orchids

   Författare :Judith Trunschke; Jon Ågren; Nina Sletvold; Allan G. Ellis; Uppsala universitet; []
   Nyckelord :Among-population variation; Ecotype; Field experiment; Floral evolution; Germination; Local adaptation; Orchidaceae; Platanthera bifolia; Phenotypic selection; Pollination; Reciprocal transplant; Trait manipulation; Biology with specialization in Ecological Botany; Biologi med inriktning mot ekologisk botanik;

   Sammanfattning : In this thesis, I combined manipulations of traits and pollination environment with analysis of phenotypic selection to examine causes of variation in strength and mode of selection on floral traits, and I conducted a reciprocal sowing experiment to test for local adaptation in germination success. I tested the following predictions (1) the opportunity for selection, and the strength of pollinator-mediated and net selection increase with increasing pollen limitation, (2) the effects of traits affecting pollinator attraction and traits affecting pollination efficiency are non-additive and this leads to pollinator-mediated correlational selection, (3) the effects of spur length on pollen removal, pollen receipt, and female fitness differ between populations with short-tongued and populations with long-tongued pollinators, and (4) local adaptation at the stage of germination contributes to the maintenance of ecotypes growing in grasslands and woodlands, respectively. LÄS MER

5. 14. Causes and consequences of quantitative trait variation for reproductive performance in hole nesting birds

   Författare :Robert Przybylo; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; timing of breeding; climate change; parental and territorial quality; morphology; sexual size dimorphism; intersexual niche differentiation; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi; Animal Ecology; zooekologi;

   Sammanfattning : This thesis examines the causes and consequences of environmental variability and individual morphological differences on breeding success and survival in three hole nesting birds.An analysis of directional and stabilising natural selection in Collared Flycatchers (Ficedula albicollis) suggested that forces of selection acting on quantitative traits are weak and cannot explain the observed sexual size dimorphism (SSD) in this species. LÄS MER

7. 15. Genetic and Genomic Analysis of DNA Sequence Variation

   Författare :Per Erik Lundmark; Ann-Christine Syvänen; Karl Michaelsson; Gert-Jan B. van Ommen; Uppsala universitet; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; SNP; NPC1; association study; allele specific expression; tagSNP; non-coding RNA; Molecular medicine genetics and pathology ; Molekylär medicin genetik och patologi ; Molekylär medicin; Molecular Medicine;

   Sammanfattning : The studies in this thesis describe the application of genotyping and allele specific expression analysis to genetic studies. The role of the gene NPC1 in Triglyceride metabolism was explored in mouse models and in humans on the population level in study I. LÄS MER