Sökning: "Daphnia pulex"

Visar resultat 1 - 5 av 7 avhandlingar innehållade orden Daphnia pulex.

  1. 1. Genetic Disequilibria and the Interpretation of Population Genetic Structure in Daphnia

    Författare :Lars M. Berg; Xavier Vekemans; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Developmental biology; breeding system; linkage disequilibrium; dispersal; genetic structure; Daphnia pulex; Utvecklingsbiologi; Developmental biology; Utvecklingsbiologi; naturvårdsbiologi; Conservation Biology;

    Sammanfattning : Understanding the processes that shape the spatial distribution of genetic variation within species is central to the evolutionary study of diversification and demography. Neutral genetic variation reflects past demographic events as well as current demographic characteristics of populations, and the correct interpretation of genetic data requires that the relative impact of these forces can be identified. LÄS MER

  3. 2. On the evolutionary effects of linkage and deleterious mutations in small populations

    Författare :Snæbjörn Pálsson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Developmental biology; Breeding systems; Daphnia pulex; deleterious mutations; linkage; neutral variation; Utvecklingsbiologi; Developmental biology; Utvecklingsbiologi; Genetics; genetik;

    Sammanfattning : The aim of this thesis is to evaluate the effect of deleterious mutations and linkage on variation in neutral markers and fitness in small populations. The study is based on two main approaches, one by using computer simulations, the other by exploring genetic variation in a cyclical parthenogen, Daphnia pulex (Crustacea: Cladocera). LÄS MER

  4. 3. Daphnids adaptive strategies to UV radiation

    Författare :Carla Eloisa Fernández; Avdelningen för Teknisk vattenresurslära; []
    Nyckelord :Cladocera; Zooplankton; Andean lakes; Daphnia; Ultraviolet radiation; Migration strategy; Photo-protection;

    Sammanfattning : This thesis focuses on the adaptive strategies of daphnids that allows them to maintain stable populations while deal with UV radiation, highlighting the differences in the responses that populations with different evolutionary histories may have.Although exposition to lethal doses in nature is unlikely, sub-lethal UV-B radiation doses may have strong impacts on zooplankton. LÄS MER

  5. 4. Hierarchical responses to organic contaminants in aquatic ecotoxicological bioassays: from microcystins to biodegradation

    Författare :Katia Montenegro; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; grazing efficiency; potential trade-off; glyphosate mineralization; DDE; potential denitrification; microcystin production; potential nitrification; DDE biodegradation; water stable isotopes; groundwater apparent age; fenthion; Chlorophyta; Daphnia pulex; diversity productivity relationship; glyphosate;

    Sammanfattning : In this thesis I explore the ecotoxicological responses of aquatic organisms at different hierarchical levels to organic contaminants by means of bioassays. The bioassays use novel endpoints or approaches to elucidate the effects of exposure to contaminants and attempt to give mechanistic explanations that could be used to interpret effects at higher hierarchical scales. LÄS MER

  7. 5. Food web dynamics in open and closed systems

    Författare :Johan Lövgren; Lennart Persson; Jonathan Chase; Umeå universitet; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER