Sökning: "sex ratio"

Visar resultat 1 - 5 av 280 avhandlingar innehållade orden sex ratio.

  1. 1. Brood sex ratio and sex differences in Tengmalm’s owl : (Aegolius funereus)

    Författare :Tim Hipkiss; Gary Bortolotti; Umeå universitet; []
    Nyckelord :Aegolius funereus; avian CHD1 genes; brood sex ratio; differential mortality; nomadism; northern Sweden; sexual size dimorphism; sibling rivalry; supplementary feeding; vole cycles; zooekologi; Animal Ecology;

    Sammanfattning : Males and females differ in morphology and behaviour, so that selection acts differently on the two sexes. This changes the relative reproductive success of males and females, and it is beneficial for parents to bias the sex ratio of their broods in favour of the sex with the best survival and breeding prospects. LÄS MER

  3. 2. Sex, hormonal factors and pancreatic cancer

    Författare :Gustav Andersson; Tumörmikromiljö; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Pancreatic cancer; Sex; Anthropometry; Hormonal factors; Tamoxifen treatment;

    Sammanfattning : Pancreatic cancer represents three percent of all incident cancer cases in developed countries, but stands the 7th most common cause of cancer related death. Worldwide, pancreatic cancer is more common among men, however in Sweden, the incidence ratio between sexes is levelling. LÄS MER

  4. 3. Sex and symbionts : New discoveries in local and regional patterns of coral ecology and reproduction

    Författare :Micaela Hellström; Michael Tedengren; Mats Grahn; John A. H. Benzie; Nancy Knowlton; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Indo-Pacific; S. elegans; G. fascicularis; Symbiodinium; size; reproduction; allozymes; ITS2; mtDNA; geography; environment; Marine ecology; Marin ekologi; marin ekotoxikologi; Marine Ecotoxicology;

    Sammanfattning : Coral reefs belong to the most diverse and the most threatened ecosystems on earth. Anthropogenic stressors and climate change have led to mortalities at levels unprecedented in modern times. The aims of this thesis are to investigate aspects of the corals’ ability to reproduce, disperse, adapt and survive. LÄS MER

  5. 4. 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

  7. 5. Endocrine Disruption in Amphibians : Developmental Effects of Ethynylestradiol and Clotrimazole on the Reproductive System

    Författare :Irina Gyllenhammar; Cecilia Berg; Ingvar Brandt; Lena Holm; Joakim Larsson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Test system; Xenopus tropicalis; Rana temporaria; sex ratio; sex differentiation; fertility; aromatase; ovary; testis; oviduct; Biology; Biologi;

    Sammanfattning : Amphibian populations are declining world-wide and one of the suggested reasons is environmental pollutants. Studies of long-term effects on the reproductive system in frogs following larval exposure to environmental pollutants are scarce. It is therefore important to develop methods to study developmental reproductive toxicity in amphibians. LÄS MER