Search for dissertations about: "directional natural selection"

Showing result 1 - 5 of 23 swedish dissertations containing the words directional natural selection.

2. 1. Tracing selection and adaptation along an environmental gradient in Populus tremula

   Author : David Hall; Pär Ingvarsson; Thomas Bataillon; Umeå universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Local adaptation; Selection; genetic differentiation; QST; FST; Association study; frequency spectra; recurrent hitchhiking; selective sweep; Tree; Populus; natural selection; quantitative genetics; Terrestrial ecology; Terrestrisk ekologi; Population Biology; populationsbiologi; genetik; Genetics;

   Abstract : The distribution of the expressed genotype is moved around in the population over time byevolution. Natural selection is one of the forces that act on the phenotype to change the patterns ofnucleotide variation underlying those distributions. READ MORE

4. 2. Self-Normalized Sums and Directional Conclusions

   Author : Fredrik Jonsson; Allan Gut; Josef Steinebach; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Self-normalized sums; heavy-tailedness; Student s t-statistic; distributional symmetry; exponential tilting; directional conclusions; reversal rates; multiple statistical inference; the Benjamini-Hochberg procedure;

   Abstract : This thesis consists of a summary and five papers, dealing with self-normalized sums of independent, identically distributed random variables, and three-decision procedures for directional conclusions. In Paper I, we investigate a general set-up for Student's t-statistic. READ MORE

5. 3. Postmating Sexual Selection and its Role in Population Divergence in Beetles

   Author : Claudia Fricke; Göran Arnqvist; David Hosken; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Biology; Callosobruchus maculatus; postmating sexual selection; speciation; laboratory selection experiment; divergence; Biologi; Biology; Biologi;

   Abstract : Speciation is the process describing the formation of new species and is at the heart of evolutionary biology. According to the biological species concept only reproductively isolated forms are regarded good species. This thesis aims at identifying evolutionary processes that cause population divergence and, ultimately, speciation. READ MORE

6. 4. Population differentiation in Lythrum salicaria along a latitudinal gradient

   Author : Katarina Olsson; Jon Ågren; Susan Kalisz; Umeå universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Ecology; additive genetic variance; clinal variation; evolutionary constraints; G matrix; genetic correlation; natural selection; pollen limitation; population differentiation; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi; ekologisk botanik; Ecological Botany;

   Abstract : In this thesis, quantitative genetic approaches, common-garden experiments, and field studies were combined to examine patterns of population differentiation and the genetic architecture of characters of putative adaptive significance in the widely distributed perennial herb Lythrum salicaria. In this work, I (1) documented patterns of population differentiation in phenology, life-history, and morphology along latitudinal gradients at different geographical scales, (2) investigated the genetic architecture of phenology, flower morphology, and inflorescence size, and (3) combined estimates of phenotypic selection in the field with information on the genetic variance-covariance matrix (G) to examine potential constraints to adaptive evolution. READ MORE

7. 5. The evolution of sexual dimorphism and its genetic underpinnings

   Author : Philipp Kaufmann; Elina Immonen; Tim Connallon; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Sexual conflict; sex-specific dominance; maintenance of genetic variance; sexual antagonism; sex chromosomes; Y haplotypes; artificial selection; sexual dimorphism; Callosobruchus maculatus; Biology with specialization in Evolutionary Genetics; Biologi med inriktning mot evolutionär genetik;

   Abstract : Sexual dimorphism often constitutes the largest phenotypic variance within species but it is puzzling how sexual dimorphisms evolve because most of the genome is shared between the sexes. Sexually antagonistic (SA) selection on a shared genome sets the stage for intralocus sexual conflict. READ MORE