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Visar resultat 1 - 5 av 22 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Embryonic Mortality and Sex Ratios in the Tree Sparrow

    Författare :Magnus Svensson; Jan Ekman; Jacob Höglund; Kathryn Arnold; Uppsala universitet; []
    Nyckelord :Ecology; Hatching success; Embryonic mortality; Sex ratio; Density dependence; Parasites; Ekologi; Passer montanus;

    Sammanfattning : Tree sparrows (Passer montanus) have been studied in two areas in Sweden since 1997. At both sites, tree sparrow eggs had remarkably low hatching success. On average only 60% of the eggs hatched. Analyses have shown that this was caused by embryonic mortality, which was highly sex biased. LÄS MER

  3. 2. Female coloration, egg carotenoids and reproductive success: gobies as a model system

    Författare :P. Andreas Svensson; Trond Amundsen; Jonathan Blount; Trondheim NTNU Department of Biology; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Akvatisk ekologi; Aquatic Ecology; Evolutionary Biology; Evolutionsbiologi;

    Sammanfattning : In two-spotted gobies (Gobiusculus flavescens), females develop an orange belly as they approach sexual maturity. Toward the end of the single breeding season, males become rare and females compete for spawnings. Nest-holding males then prefer females with more colourful bellies and this trait has been suggested to act as a female ornament. LÄS MER

  4. 3. Population dynamics and demography - inferences from stochastic models

    Författare :Jonas Knape; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : Time series analysis of population abundances is a common approach to making inferences about population dynamics, and especially for estimating density dependence. Traditionally the impact of potential errors in observations or measurements of the abundances on inference has been ignored. LÄS MER

  5. 4. The influence of food abundance patterns and predation on breeding ducks with a special emphasis on the interactions between ducklings and fish

    Författare :Lisa Dessborn; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : Ducks breeding in Fennoscandia represent a large part of the total population in Europe, and variations in reproductive success can affect continental population trajectories. It is therefore essential to understand processes affecting breeding success. LÄS MER

  7. 5. Dispersal, inbreeding and fitness in natural populations

    Författare :Bengt Hansson; MEMEG; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; immigration; inbreeding; inbreeding depression; heterozygosity; microsatellite; great reed warbler; bird; Djurekologi; Animal ecology; philopatry; heritability; founder event; dispersal; bottleneck;

    Sammanfattning : To evaluate how inbreeding affects the viability of small populations, it is crucial to determine what constitutes a population (i.e., the number of breeders in local patches and the degree of dispersal), and also to estimate the reproductive consequences of philopatry and emigration. LÄS MER