Sökning: "extinction risk"
Visar resultat 16 - 20 av 43 avhandlingar innehållade orden extinction risk.
16. Genetic gating of human fear, fear learning and extinction : psychophysiological, brain imaging (fMRI) and clinical studies
Sammanfattning : Individuals differ in their reaction to the same environmental stressor. After being opposed to the same trauma, some individuals will develop affective pathologies, while others will not. This is assumed to result, at least partly, from a differential genetic vulnerability. LÄS MER
17. Population dynamics in variable environments – impacts of noise colour and synchrony
Sammanfattning : Environmental variation is an essential part of population dynamics, and two characteristics of such variation—variance and the temporal autocorrelation termed ‘noise colour’—are essential for determining the persistence of a population. In addition, the spatial correlation of local environmental variation between habitat patches (i.e. LÄS MER
18. Dynamics of ecological communities in variable environments : local and spatial processes
Sammanfattning : The ecosystems of the world are currently facing a variety of anthropogenic perturbations, such as climate change, fragmentation and destruction of habitat, overexploitation of natural resources and invasions of alien species. How the ecosystems will be affected is not only dependent on the direct effects of the perturbations on individual species but also on the trophic structure and interaction patterns of the ecological community. LÄS MER
19. Extinctions in Ecological Communities : direct and indirect effects of perturbation on biodiversity
Sammanfattning : In the dawning of what may become Earth’s 6th mass extinction the topic of this thesis, understanding extinction processes and what determines the magnitude of species loss, has become only too relevant. The number of known extinctions (~850) during the last centuries translates to extinction rates elevated above the background rate, matching those of previous mass extinction events. LÄS MER
20. Distribution and persistence of epiphyte metapopulations in dynamic landscapes
Sammanfattning : Habitat loss is a major cause of species extinction. Old trees have declined, and this continues because of poor management. Examples are development of secondary woodland in semi-open grasslands, and lack of natural tree regeneration. We therefore can expect that species associated with old tree are declining. LÄS MER