Sökning: "Speciation"

Visar resultat 21 - 25 av 281 avhandlingar innehållade ordet Speciation.

1. 21. Hybrid zones and speciation – insights from the European crow hybrid zone

   Författare :Fredrik Haas; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; microsatellites; mc1r; introgression; hybrid zone; speciation; European crow; Corvus corone; habitat preferences; neural network; sexual imprinting; assortative mating;

   Sammanfattning : In hybrid zones genetically differentiated populations meet and interbreed. As they result from ongoing divergence and potential speciation, such zones provide opportunities to study how different factors affect this process. The hybrid zone between the all black carrion crow (Corvus corone corone) and the grey and black hooded crow (Corvus c. LÄS MER

3. 22. The role of Assortative Mating in the Initial Stages of Sympatric and Parapatric Speciation

   Författare :Emma Rova; Mats Björklund; Göran Arnqvist; James Mallet; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Callosobruchus maculatus; host fidelity; assortative mating; inbreeding; experimental evidence; sympatric speciation; parapatric speciation; Biology; Biologi; Biologi med inriktning mot zooekologi; Biology with specialization in Animal Ecology;

   Sammanfattning : Divergence in the face of gene flow is perhaps the most wildly disputed subject among researchers through time. The debate is an old one and we find its origin as far back as the era of Darwin. LÄS MER

4. 23. Liquid Membrane Techniques for Trace Metal Analysis and Speciation in Environmental and Biological Matrices

   Författare :Kuria Ndung'u; Centrum för analys och syntes; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Analytical chemistry; Pb and Organotin species; MMLLE; SLM; GC MS; PSA; GFAS; FAAS; ICP-MS; Speciation; DEHPA; Aliquat-336; trace metals; Cr III ; Cr VI ; Analytisk kemi;

   Sammanfattning : In this thesis, liquid-membrane-based methods for the analysis of trace metal species in samples of environmental and biological origin were developed. By incorporating extracting reagents in the membrane liquid, trace metal ions were selectively separated from humic-rich natural waters and urine samples, prior to their determination using various instrumental techniques. LÄS MER

5. 24. Modeling of glyphosate and metal-glyphosate speciation in solution and at solution-mineral interfaces

   Författare :Caroline Jonsson; Staffan Sjöberg; Per Persson; Bernd Nowack; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; herbicide; glyphosate; surface complexation model; speciation; goethite; aged gamma-alumina; bayerite; manganite; cadmium II ; aluminium III ; potentiometric titration; adsorption; Chemistry; Kemi;

   Sammanfattning : Glyphosate (N-(phosphonomethyl)glycine, PMG, H3L) is a widely used organophosphorous herbicide. It interacts with metal ions and mineral surfaces, which may affect its mobility, degradation and bioavailability in the environment. However, these interactions are far from fully understood. LÄS MER

7. 25. Unraveling the importance of thiol compounds on mercury speciation, uptake and transformation by the iron-reducer Geobacter sulfurreducens

   Författare :Mareike Franziska Gutensohn; Erik Björn; Ulf Skyllberg; Jeffra K. Schaefer; Vera Slaveykova; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; mercury; low molecular mass thiols; speciation; uptake; methylation; reduction; Hg 0 ; Hg II ; MeHg; Geobacter sulfurreducens; ICP-MS; LC-MS MS; X-ray absorption spectroscopy; cell physiology;

   Sammanfattning : The biogenic methylation of inorganic, divalent mercury (Hg(II)) by methylating microorganisms leads to formation and bioaccumulation of monomethyl mercury (MeHg) in the environment and can cause severe damage to ecosystems and human health. Diverse microorganisms carry the gene sequence hgcAB and are able to methylate Hg(II) intracellularly. LÄS MER