Sökning: "extinction risk"

Visar resultat 11 - 15 av 43 avhandlingar innehållade orden extinction risk.

  1. 11. Empirical and theoretical studies of population trends and extinction risks

    Författare :Tobias Jeppsson; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : Empirical and theoretical approaches are needed to solve the current problem of increased extinction risk for many species. Thus, this thesis focuses on: (1) ways to estimate population trends for a large number of species, and (2) a predictive framework for identifying vulnerable populations from species traits or life history traits to allow for more proactive conservation actions. LÄS MER

  3. 12. Population-level consequences of variation

    Författare :Lena Wennersten; Anders Forsman; Olof Leimar; Deepa Agashe; Linnéuniversitetet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; colour polymorphism; diversity; establishment success; evolutionary changes; population-level consequences; predation risk; Tetrix subulata; variation; Evolutionary Biology; Evolutionsbiologi;

    Sammanfattning : Consequences of within population variation have recently attracted an increased interest in evolutionary ecology research. Theoretical models suggest important population-level consequences, but many of these predictions still remain to be tested. LÄS MER

  4. 13. Biodiversity and Species Extinctions in Model Food Webs

    Författare :Charlotte Borrvall; Bo Ebenman; Owen Petchey; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; biodiversity; food webs; redundancy; relaxation time; stability; stochasticity; species deletion; species extinction; Biology; Biologi;

    Sammanfattning : Many of the earth’s ecosystems are experiencing large species losses due to human impacts such as habitat destruction and fragmentation, climate change, species invasions, pollution, and overfishing. Due to the complex interactions between species in food webs the extinction of one species could lead to a cascade of further extinctions and hence cause dramatic changes in species composition and ecosystem processes. LÄS MER

  5. 14. Metapopulation ecology of Osmoderma eremita - dispersal, habitat quality and habitat history

    Författare :Jonas Hedin; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; extinction debt; habitat history; habitat quality; pheromone; telemetry; capture-mark-recapture; metapopulation; dispersal; oak; Osmoderma eremita; beetle; Animal ecology; Djurekologi;

    Sammanfattning : This thesis starts with a review of different biodiversity assessment methods in forests and the rest deals with the metapopulation ecology of Osmoderma eremita, a threatened beetle living in hollow trees. I concentrate on the effect of dispersal, habitat quality and habitat history for the presence, population size and future survival of this species. LÄS MER

  7. 15. Habitat selection, nest predation and conservation biology in a Black-tailed Godwit (Limosa limosa) population

    Författare :Tomas Johansson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Developmental biology; Black-tailed godwit; Limosa limosa; nest site selection; nest predation; philopatry; risk analysis; Utvecklingsbiologi; Developmental biology; Utvecklingsbiologi; populationsbiologi; Population Biology;

    Sammanfattning : This thesis focuses on a black-tailed godwit (Limosa limosa) population, consisting of 35-40 pairs, that breeds on a grazed shore meadow on SE Gotland, Sweden. The small size of the population makes it more prone to extinction due to chance events, than a larger population.The godwits showed microhabitat preferences when choosing nest sites. LÄS MER