Sökning: "rare species"
Visar resultat 21 - 25 av 142 avhandlingar innehållade orden rare species.
21. Community Robustness Analysis : Theoretical Approaches to Identifying Keystone Structures in Ecological Communities
Sammanfattning : Most of the world’s ecosystems suffer from stress caused by human activities such as habitat destruction, fragmentation, overexploitation of species and climate change. These factors affect the reproduction and/or survival of individual species as well as interactions between species in ecological communities. LÄS MER
22. Mechanisms and mediators of apoptosis : with special reference to hematological disorders
Sammanfattning : Life and death are inextricably entwined. Naturally occurring cell death or apoptosis is essential for the of homeostasis and serves to remove extraneous or dangerous cells in a swift and unobtrusive manner. work has demonstrated that such cell death is genetically regulated and transpires according to evolutionarily conserved pathways. LÄS MER
23. Genetic variation, clonal diversity and breeding system in sedges (Carex)
Sammanfattning : In this thesis I investigate genetic variation in clonal plants within the wind-pollinated plant family Cyperaceae and, in particular, in species of Carex. Clonal diversity and the spatial distribution of clones (genets) within populations was investigated in Carex bigelowii (in Iceland and Scandinavia) and C. LÄS MER
24. Island biogeography of young land uplift islands - viewed through the lens of bryophytes in a northern Swedish archipelago
Sammanfattning : Increasing habitat fragmentation and rapid global warming is changing the conditions for species populations and ecological communities around the world. This presents challenges for the maintenance of biodiversity and a dominant paradigm for conservation in fragmented habitats is given by island biogeography and metapopulation (or metacommunity) ecology. LÄS MER
25. Rarity in boreal stream: patterns, causes and consequences
Sammanfattning : Patterns of site occupancy among boreal stream insects were studied in central Sweden with focus on sparsely distributed species and the role of dispersal and niche limitations.In the study of dispersal limitation, I found that effects of an extraordinarily harsh winter in small to medium-sized streams were strongest in sites located in small streams and far from lake outlets. LÄS MER