Sökning: "seed size"

Visar resultat 1 - 5 av 82 avhandlingar innehållade orden seed size.

1. 1. The role of regeneration in plant niche differentiation and habitat specialization

   Författare :Dirk-Jan ten Brink; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; seed mass; seed size; drought; shade; seed germination; seed dormancy; seedling establishment; plant community ecology; assembly rules; habitat specialization; plant recruitment; Regeneration; niche differentiation; phylogenetic independent contrasts; plant traits; soil fertility; comparative ecology;

   Sammanfattning : To predict the effects of environmental change and nature management on the distribution of plant species, it is crucial to understand the mechanisms of plant niche differentiation and habitat specialization. The importance to habitat specialization of particular plant traits and requirement of the regenerative phase of the plants life has received scanty interest. LÄS MER

3. 2. Effects of seed size and habitat on recruitment patterns in grassland and forest plants

   Författare :Karin Lönnberg; Ove Eriksson; Per Milberg; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Seed size; seedling establishment; seedling survival; recruitment; seed removal; co-existence; game-theory; Plant Ecology; växtekologi;

   Sammanfattning : A trade-off between seed size and seed number is central in seed ecology, and has been suggested to be related to a trade-off between competition and colonization, as well as to a trade-off between stress tolerance and fecundity. Large seeds endure hazards during establishment, such as shading, drought, litter coverage and competition from other plants, better than do small seeds, due to a larger amount of stored resources in the seed. LÄS MER

4. 3. Plant-animal interactions and seed output of two insectpollinated herbs

   Författare :Anna R. Waites; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; plant reproduction; pollen limitation; pollinator behaviour; heterostyly; seed predation; Lythrum salicaria; Pedicularis palustris; stigma receptivity; self-pollen; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

   Sammanfattning : I combined comparative and experimental studies in the field and in the greenhouse to examine factors influencing reproductive success in two insect-pollinated herbs, the tristylous, selfincompatible perennial Lythrum salicaria and the self-compatible, biennial Pedicularis palustris. More specifically, I explored (i) the effects of plant population characteristics on the intensity and outcome of interactions with pollinators and seed predators, (ii) whether flower morphology affects duration of stigma receptivity, and (iii) whether damage-induced reduction in floral display reduces pollinator visitation and increases pollen limitation. LÄS MER

5. 4. Selection during Early Life Stages and Local Adaptation in Arabidopsis thaliana

   Författare :Froukje M. Postma; Jon Ågren; Kathleen Donohue; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Dormancy cycling; Germination timing; Maternal effects; Natural variation; QTL mapping; Seed bank; Seed dormancy; Structural Equation Modeling; Biology with specialization in Ecological Botany; Biologi med inriktning mot ekologisk botanik;

   Sammanfattning : Organisms are often adapted to their local environment, but the role of early life stages in adaptive differentiation among populations remains poorly known. The aim of my thesis was to investigate the contribution of early life stages to the magnitude and genetic basis of local adaptation, and to identify the underlying adaptive traits. LÄS MER

7. 5. Adaptation and Constraint in the Plant Reproductive Phase

   Författare :Kjell Bolmgren; Ove Eriksson; Bengt Oxelman; Jeff Ollerton; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; phenology; fleshy fruits; phylogenetic comparative methods; phylogenetic constraints; Rhamnus; Frangula; Frangula alnus; key innovations; allometry; diversity; phylogeny; seed size; frugivory; germination; recruitment; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

   Sammanfattning : Conservatism is a central theme of organismic evolution. Related species share characteristics due to their common ancestry. Some concern have been raised among evolutionary biologists, whether such conservatism is an expression of natural selection or of a constrained ability to adapt. LÄS MER