Search for dissertations about: "ekologi"

Showing result 11 - 15 of 1545 swedish dissertations containing the word ekologi.

  2. 11. Investigations of species richness effects on ecosystem functioning using stream-living macroinvertebrates as model organisms

    Author : Micael Jonsson; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Ecology; Species richness; species loss; process rates; ecosystem function; streams; macroinvertebrates; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

    Abstract : The work in this thesis deals with effects of changed species richness on process rates among stream-living macroinvertebrates. Global biodiversity is decreasing rapidly and it is poorly known what the consequences of this loss may be for ecosystems and the services they provide. READ MORE

  4. 12. Food web dynamics in open and closed systems

    Author : Johan Lövgren; Lennart Persson; Jonathan Chase; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Ecology; allochtonous input; cross habitat foraging; donor control; heterogeneity within trophic level; compensation; food web; littoral; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

    Abstract : This thesis is a summary of enclosure and microcosm experiments that aimed to study the impact of allochtonous subsidies on food web dynamics in a heterogeneous food web. In the enclosure studies, a three trophic level littoral food web was used. READ MORE

  5. 13. Vegetation patterns and processes in riparian landscapes

    Author : Birgitta Malm Renöfält; Christer Nilsson; Peter Edwards; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Ecology; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

    Abstract : The objective of this study was to increase understanding of the processes structuring and controlling the species richness of riparian plant communities. In particular, I examined the unimodal relationship, found in many rivers, between plant species richness and location along the river corridor. READ MORE

  6. 14. Polyandry and the evolution of reproductive divergence in insects

    Author : Tina Nilsson; Göran Arnqvist; David Hosken; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Ecology; Bruchidae; cryptic female choice; multiple mating; sexual conflict; sexually antagonistic coevolution; sexual selection; speciation; sperm competition; Tenebrionidae; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

    Abstract : Multiple mating by females is common in nature. Yet, the evolution and maintenance of polyandry remains a bit of an evolutionary puzzle. It was my aim in this thesis to reach a greater understanding of this phenomenon as well as to investigate the consequences of polyandry on the evolution of reproductive divergence in insects. READ MORE

  7. 15. Population differentiation in Lythrum salicaria along a latitudinal gradient

    Author : Katarina Olsson; Jon Ågren; Susan Kalisz; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Ecology; additive genetic variance; clinal variation; evolutionary constraints; G matrix; genetic correlation; natural selection; pollen limitation; population differentiation; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi; ekologisk botanik; Ecological Botany;

    Abstract : In this thesis, quantitative genetic approaches, common-garden experiments, and field studies were combined to examine patterns of population differentiation and the genetic architecture of characters of putative adaptive significance in the widely distributed perennial herb Lythrum salicaria. In this work, I (1) documented patterns of population differentiation in phenology, life-history, and morphology along latitudinal gradients at different geographical scales, (2) investigated the genetic architecture of phenology, flower morphology, and inflorescence size, and (3) combined estimates of phenotypic selection in the field with information on the genetic variance-covariance matrix (G) to examine potential constraints to adaptive evolution. READ MORE