Search for dissertations about: "pollen limitation"

Showing result 1 - 5 of 15 swedish dissertations containing the words pollen limitation.

2. 1. To Bee or Not to Be : Critical Floral Resources of Wild-Bees

   Author : Magnus Larsson; Anders L Nilsson; Jon Ågren; Björn Cederberg; James H Cane; Uppsala universitet; []
   Keywords : Ecology; Andrena hattorfiana; Andrena marginata; Andrenidae; Knautia arvensis; limitation; oligolecty; pollen; pollination; solitary bee; specialist bee; Succisa pratensis; Ekologi;

   Abstract : In recent decades, the development of strategies to prevent or slow the loss of biodiversity has become an important task for ecologists. In most terrestrial ecosystems wild-bees play a key role as pollinators of herbs, shrubs and trees. The scope of this thesis was to study 1) pollinator effectiveness of specialist bees vs. READ MORE

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

   Author : Anna R. Waites; Umeå universitet; []
   Keywords : 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;

   Abstract : 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. READ MORE

5. 3. Reproductive patterns of birches (Betula spp.) in northern Sweden

   Author : Stig-Olov Holm; Umeå universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Reproduction; Betula; seed-quality; seed-set; pollination; pollen-limitation; pollen-competition; tree-line; environmental gradient; seed weight; seedling survival; Semudobia;

   Abstract : The aim of this thesis was to study patterns of reproduction of Betula pendula and B. pubescens coll. along an altitudinal, coastal-inland, gradient in northern Sweden. The altitudinal variation was related to the distribution of the birch taxa along the gradient. READ MORE

6. 4. Herbivory, pollen limitation and population dynamics in Lathyrus vernus

   Author : Johan Ehrlén; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Vårärt; Ekologi; Botanik; Växtekologi;

   Abstract : .... READ MORE

7. 5. 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