Sökning: "population cycles"

Visar resultat 6 - 10 av 85 avhandlingar innehållade orden population cycles.

  1. 6. Business Cycles, Unemployment and Job Search : Essays in Macroeconomics and Labor Economics

    Författare :Andreas Mueller; Per Krusell; Mark Aguiar; Stockholms universitet; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Business Cycles; Unemployment; Unemployment Insurance; Wage Dispersion; Time Use; Job Search; Economics; Nationalekonomi; Economics; nationalekonomi;

    Sammanfattning : This thesis consists of four essays. The first essay, "Separations, Sorting and Cyclical Unemployment", establishes a new fact about the compositional changes in the pool of unemployed over the U.S. business cycle and evaluates a number of theories that can potentially explain it. LÄS MER

  3. 7. Cycles of voles, predators, and alternative prey in boreal Sweden

    Författare :Birger Hörnfeldt; S. Erlinge; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; 3-4 year cycles; Clethrionomys glareolus; Clethrionomys rufocanus; Microtus agrestis; snap-trapping; rate of change; population regulation; delayed density-dependence; time-lag mechanism; seasonality; predation; food; predator avoidance; foraging behaviour; Aegolius funereus; nest boxes; numerical response; nomadism; Vulpes vulpes; Sarcoptes scabiei vulpes; Lepus timidus; Francisella tularensis; Tetraonidae; hunting statistics; zooekologi; Animal Ecology;

    Sammanfattning : Bank voles, grey-sided voles, and field voles had synchronous 3-4 year density cycles with variable amplitudes which averaged about 200-fold in each species. Cycles of vole predators (red fox and Tengmalm's owl), and their (foxes') alternative prey (mountain hare and forest grouse) lagged behind the vole cycles. LÄS MER

  4. 8. Life histories and population dynamics

    Författare :Annie Jonsson; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : During the last decades there has been a growing interest and attention to random variation in population densities and their causes. It has been shown that even in constant environments (deterministic population growth) the dynamics of populations can display random like behaviour depending on parameter values. LÄS MER

  5. 9. Geographic variation in life cycles : Local adaptation and ecological genetics in a temperate butterfly

    Författare :Olle Lindestad; Karl Gotthard; Sören Nylin; Christopher W Wheat; Greg Ragland; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; voltinism; local adaptation; insect; life cycle; seasonality; genomics; life history; zoologisk ekologi; Animal Ecology;

    Sammanfattning : Conditions in nature change with the seasons, necessitating seasonal adaptations that synchronize the life cycles of organisms with their surroundings. Such regulatory adaptations must vary between populations to track local variation in climate and seasonality; this local adaptation is facilitated by locally specific seasonal cues, but may be hampered by gene flow and genetic history. LÄS MER

  7. 10. Distribution and abundance of genetic variation in the arctic fox

    Författare :Love Dalén; Anders Angerbjörn; Robert K. Wayne; Stockholms universitet; []
    Nyckelord :population genetics; DNA; ecology; population history; gene flow; Alopex lagopus;

    Sammanfattning : This thesis investigates how changes in population size and spatial movements of individuals have shaped the distribution and abundance of neutral genetic variation in the arctic fox. This is done through mitochondrial and microsatellite DNA analyses on samples covering most of the species’ distribution, but with special emphasis on Scandinavia. LÄS MER