Sökning: "natural selection"

Visar resultat 41 - 45 av 1236 avhandlingar innehållade orden natural selection.

1. 41. Selection and ranking procedures based on likelihood ratios

   Författare :Jayanti Chotai; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Subset selection; likelihood ratio; hypothesis testing; order restrictions; normal distribution; uniform distribution; complete ranking; P* -condition; loss function;

   Sammanfattning : This thesis deals with random-size subset selection and ranking procedures• • • )|(derived through likelihood ratios, mainly in terms of the P -approach.Let IT , . .. LÄS MER

3. 42. Sexual selection in the collared flycatcher (Ficedula albicollis) : A life-history perspective

   Författare :Anna Qvarnström; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; Sexual selection; life-history; honest signalling; fighting ability; genotype-environment interaction; direct benefits; indirect benefits; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi; Animal Ecology; zooekologi;

   Sammanfattning : This thesis integrates sexual selection theory with life history theory to elucidate the causes and consequences of variation in a male secondary sexual trait. The model organism, the collared flycatcher (Ficedula albicollis), was studied on Gotland, Sweden. LÄS MER

4. 43. Sex, Sperm and Speciation : On sexual selection and fertility in hybridizing flycatchers

   Författare :Murielle Ålund née Podevin; Anna Qvarnström; Simone Immler; Leonie Moyle; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; sperm biology; sexual selection; speciation; hybridization; cryptic female choice; fertility; Ficedula flycatchers; Biologi med inriktning mot zooekologi; Biology with specialization in Animal Ecology;

   Sammanfattning : Sexual reproduction entails complex co-evolution between the sexes, necessary for successful fertilization, ensuring individual and population-level fitness. Interfertility is the main criterion for species definition and understanding speciation requires detailed studies of reproductive barriers. LÄS MER

5. 44. Genetic variation in natural populations: a modeller's perspective

   Författare :Marina Rafajlovic; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; coalescent process; site frequency spectrum; multiple paternity; dominant clone; divergent selection;

   Sammanfattning : Thanks to advances in genome sequencing, empirical patterns of within- and between-species genetic variation are readily available. By studying these patterns much has been learned about the evolutionary histories of species. But the causes and consequences of different evolutionary histories are still difficult to tell apart. LÄS MER

7. 45. Covariate selection and propensity score specification in causal inference

   Författare :Ingeborg Waernbaum; Xavier de Luna; Elena Stanghellini; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Covariate selection; graphical models; matching; observational studies; treatment effects; unconfoundedness; Statistics; Statistik;

   Sammanfattning : This thesis makes contributions to the statistical research field of causal inference in observational studies. The results obtained are directly applicable in many scientific fields where effects of treatments are investigated and yet controlled experiments are difficult or impossible to implement. LÄS MER