Sökning: "population density"

Visar resultat 6 - 10 av 501 avhandlingar innehållade orden population density.

  1. 6. Species interactions govern evolutionary and ecological effects of population harvesting

    Författare :Anna Gårdmark; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; population harvesting; species interactions; ecological community; Ekologi; Ecology; competition; predation; fisheries; spatial dynamics; maturation; population dynamics; life-history evolution; adaptation;

    Sammanfattning : Harvesting changes population abundance and can affect adaptation of several life-history traits. Harvesting can also have indirect effects ? effects on non-target species and secondary effects on target species ? because interactions between species in a community determine the relevant ecological and evolutionary feedback environment. LÄS MER

  3. 7. Population size, viability and genetic diversity in the orchid Gymnadenia conopsea

    Författare :Linus Söderquist; Nina Sletvold; Sophie Karrenberg; Hans Jacquemyn; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; demography; extinction probability; genetic diversity; genetic rescue; genetic structure; Gymnadenia conopsea; orchid conservation; population viability; population size; Biology with specialization in Ecological Botany; Biologi med inriktning mot ekologisk botanik;

    Sammanfattning : In this thesis, I combined controlled crosses with genetic and demographic data to examine how a main conservation value indicator, population size, was associated with estimates of population viability. I focused on the still common, but decreasing, perennial orchid Gymnadenia conopsea at two spatial scales—locally on the island Öland, in SE Sweden, and regionally across Scandinavia. LÄS MER

  4. 8. Foot lesions in diabetic patients aged 15-20 years : a population-based study

    Författare :Bengt Borssén; Folke Lithner; Umeå universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Diabetes mellitus; Foot deformities; Sensory threshold; M. extensor digitorum brevis;

    Sammanfattning : Foot problems are not only the most common but in general also the most severe of the diabetic complications. The age group 15-50 yrs in this study was chosen because these patients were considered to be at their most active age and were felt to require optimal foot function. LÄS MER

  5. 9. Population dynamics of tundra-living grey-sided voles

    Författare :Per Ekerholm; Lauri Oksanen; Rolf Anker Ims; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; Population dynamics; Tundra; Grey-sided vole; Cycles; Vole specialist predators; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi; zooekologi; Animal Ecology;

    Sammanfattning : This thesis deals with the dynamics of tundra living voles with emphasis on the most common one, the grey-sided vole (Clethrionomys rufocanus). The tundra area chosen for the study was Finnmarksvidda, a vast flatland in northernmost Norway. LÄS MER

  7. 10. Population biology of the clonal plant Ranunculus lingua

    Författare :Mats E. Johansson; Christer Nilsson; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; clonal fragmentation; emergent macrophytes; fungal pathogens; hydrochoiy; invertebrate grazing; marginal population; Peronospora gigantea Prasocuris phellandrt regional abundance; rhizome production; size-number trade-off; vegetative reproduction; water-level fluctuation;

    Sammanfattning : The scope of this thesis was to identify, describe and quantify important life-history traits for the pseudoannual aquatic plant Ranunculus lingua in different ecological settings, by comparing populations from geographically marginal vs. central habitats. LÄS MER