Sökning: "comparative ecology"

Visar resultat 1 - 5 av 48 avhandlingar innehållade orden comparative ecology.

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. The ecological significance of cleistogamy

   Författare :Henrik Berg; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; bet-hedging; chasmogamous; enviromnental variation; fitness; outcrossing; progeny; selling; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi; ekologisk botanik; Ecological Botany;

   Sammanfattning : Various aspects of cleistogamy, a reproductive system combining selfing in closed (cleistogamous) flowers and potential outcrossing in open (chasmogamous) flowers, were investigated in four perennial species. The main purpose was to shed some light on the adaptive value of having a dual reproductive strategy, and to test some hypotheses on the maintenance of xenogamy. LÄS MER

4. 3. Getting to know Trioza apicalis (Homoptera: Psylloidea) – a Specialist Host-Alternating Insect with a Tiny Olfactory System

   Författare :Lina Kristoffersen; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physiology of invertebrates; Djurs anatomi och morfologi; Entomologi; plant parasitology; Entomology; Ekologi; Ecology; glomeruli; antennal lobe; olfactory receptor neurons electrophysiology; antennae; behaviour; olfaction; Sternorrhyncha; psyllid; Ryggradslösa djurs fysiologi; animal morphology; Animal anatomy; växtparasitologi;

   Sammanfattning : This thesis comprises ecological, morphological and physiological studies of the carrot psyllid Trioza apicalis (Homoptera: Psylloidea) with particular focus on olfaction. Data from inventories of winter habitats suggest that T. apicalis prefer Picea abies over Pinus sylvestris and Juniperus communis as winter hosts. LÄS MER

5. 4. Pollinators, Enemies, Drought, and the Evolution of Reproductive Traits in Primula farinosa

   Författare :Per Toräng; Jon Ågren; Johan Ehrlén; Rebecca Irwin; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Ecology; Alternative reproductive strategies; climate change; facilitation; floral display; flowering phenology; frequency-dependent selection; genetic diversity; life-history strategies; local adaptation; pollination; predation; Primula farinosa; reproductive effort; soil disturbance; stochastic growth rate; Ekologi;

   Sammanfattning : In this thesis, I combined comparative and experimental approaches to examine selection on reproductive traits and population differentiation in the insect-pollinated, self-incompatible, perennial herb Primula farinosa. More specifically, I (1) determined whether the effects of floral display and interactions with pollinators and seed predators, and plant reproductive success were frequency-dependent and affected by surrounding vegetation context, (2) examined the consequences of intermittent drought years on population dynamics using numerical simulations based on demographic data collected over seven years, (3) analyzed among-population differentiation in flowering phenology and reproductive allocation, and its relationship to soil-depth at the site of origin. LÄS MER

7. 5. Circadian Rhythms in Moth Sex Pheromone Communication

   Författare :Germund von Wowern; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physiology of invertebrates; växtparasitologi; Entomologi; plant parasitology; Entomology; Ecology; Ekologi; locomotor activity; social synchronisation; PDH; corazonin; PBAN; pheromone response; sex phermone; Lepidoptera; Ryggradslösa djurs fysiologi; calling behaviour; circadian rhythm;

   Sammanfattning : Sex pheromone communication and related physiological processes are regulated by circadian clock mechanisms in many moth species. This thesis includes studies of circadian rhythms in sexually relevant behaviours and communication in the Egyptian cotton leafworm Spodoptera littoralis, the turnip moth Agrotis segetum, the Indian meal moth Plodia interpunctella and the Mediterranean flour moth Ephestia kuehniella. LÄS MER