Sökning: "population fragmentation"

Visar resultat 1 - 5 av 74 avhandlingar innehållade orden population fragmentation.

  1. 1. European Black Grouse : MHC Genetic Diversity and Population Structure

    Författare :Tanja Strand; Jacob Höglund; Helena Westerdahl; David S. Richardson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Major Histocompatibility Complex; BLB; balancing selection; concerted evolution; bottleneck; fragmentation; 3 UTR; Biologi med inriktning mot populationsbiologi; Biology with specialization in Population Biology;

    Sammanfattning : Black grouse Tetrao tetrix is a bird species composed of large, continuous as well as severely reduced and fragmented populations, making it an optimal species to investigate how genetic diversity is affected by habitat fragmentation. I have focused on genetic diversity in the Major Histocompatibility Complex (MHC) to measure the ability of the black grouse to respond to environmental changes. LÄS MER

  3. 2. Population Fragmentation and Genetic Variation in Grouse

    Författare :Jobs Karl Larsson; Jacob Höglund; Stuart B. Piertney; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology; Bonasa sewerzowi; bottleneck; genetic drift; genetic variation; inbreeding; isolation; microsatellites; population structure; Tetrao tetrix; Biologi; Biology; Biologi;

    Sammanfattning : In this thesis the genetic variation of two grouse species, the Chinese grouse (Bonasa sewersowi) and the Black grouse (Tetrao tetrix) was examined with neutral genetic markers: microsatellites. Habitat fragmentation and isolation leads to structuring among and loss of genetic variation within populations. LÄS MER

  4. 3. Population biology of the clonal plant Ranunculus lingua

    Författare :Mats E. Johansson; Christer Nilsson; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; clonal fragmentation; emergent macrophytes; fungal pathogens; hydrochoiy; invertebrate grazing; marginal population; Peronospora gigantea Prasocuris phellandrt regional abundance; rhizome production; size-number trade-off; vegetative reproduction; water-level fluctuation;

    Sammanfattning : The scope of this thesis was to identify, describe and quantify important life-history traits for the pseudoannual aquatic plant Ranunculus lingua in different ecological settings, by comparing populations from geographically marginal vs. central habitats. LÄS MER

  5. 4. Paleolimnological reconstructions of fish population changes in acidified lakes

    Författare :Fredrik Palm; Göteborgs universitet; []
    Nyckelord :Acidification; Chaoborus; C. flavicans; C. obscuripes; Cyprinids; Daphnia; Fish loss; Fish community composition; Ephippia; Fragmentation; Mandibles; Perch; Roach; Sediments; 210-Pb chronology;

    Sammanfattning : This thesis deals with the potential of using subfossil Chaoborus spp. and Daphnia spp. remains preserved in lake sediments to reveal past fish community alterations related to progressive acidification. LÄS MER

  7. 5. Investigating genetic factors behind the decline of a threatened plant species – Tephroseris integrifolia (Asteraceae)

    Författare :Kerstin Isaksson; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; quantitative genetics.; AFLP; local genetic variation; relict populations; fragmentation; small populations; sporophytic self-incompatibility; extinction; threatened species; Inbreeding depression; population structure;

    Sammanfattning : Landscape change in Europe has caused the decline of many grassland species. Tephroseris integrifolia (Asteraceae) is one species which has declined rapidly in Sweden since the 19th century. LÄS MER