Sökning: "Current evolution"

Visar resultat 1 - 5 av 356 avhandlingar innehållade orden Current evolution.

1. 1. Phylogenomic Analysis of Vertebrate Evolution

   Författare :Björn Hallström; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; mammals; phyogenetics; phylogenomics; vertebrates; evolution;

   Sammanfattning : The field of phylogenomics has emerged during the last five years, as the number of fully or partially sequenced genomes has increased rapidly. Using whole genomes for phylogenetic studies greatly increases the accuracy of the trees determined, and can potentially resolve phylogenetic questions that could not be resolved bu studies using only a few gene sequences. LÄS MER

3. 2. Supporting Software Architecture Evolution

   Författare :Mikael Svahnberg; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Software Architecture; Software Evolution; Software Engineering Decision Support;

   Sammanfattning : Today it is more a rule than an exception that software systems have a lifecycle of more than several years. Hence, software evolution is inevitable. During the life span of a software system the domain in which the system is working evolves and changes. LÄS MER

4. 3. Molecular aspects of pheromone evolution in moths

   Författare :David Abraham; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ekologi; 28S genephylogenetic reconstruction pheromone types; ND1 genes; PBP; Pheromone-binding protein genes; Drepanidae; Noctuidae; Geometridae; Lepidoptera; Insect; Evolution; Olfaction; Ecology;

   Sammanfattning : Moths rely on the sense of smell (olfaction) as the main sensory input system in search for potential food sources and in selection of suitable females by males. Specific pheromones are fundamental to the reproductive isolation of species and consequently the olfactory system of moths has evolved to a high level of sensitivity and specificity. LÄS MER

5. 4. 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

7. 5. On the Origin and Evolution of the Mitochondrial Ribosome

   Författare :Victor Tobiasson; Alexey Amunts; Loren Williams; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ribosome; mitochondria; evolution; structural biology; biokemi; Biochemistry;

   Sammanfattning : The ribosome is among the most ancient, intricate and well studied macromolecular complexes in biology. Predating the earliest divergence of life, its core molecular structure has remained mostly unchanged for more than three billion years. LÄS MER