Sökning: "broods"

Visar resultat 1 - 5 av 15 avhandlingar innehållade ordet broods.

  1. 1. Survival patterns and density-dependent processes in breeding mallards Anas platyrhynchos

    Författare :Gunnar Gunnarsson; Kjell Sjöberg; Johan Elmberg; Per Lundberg; Robert Clark; Högskolan Kristianstad; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; broods; dabbling ducks; density dependence; ducklings; experiments; models; mortality; nest predation; regulation; survival; Terrestrial ecology; Terrestrisk ekologi;

    Sammanfattning : Measuring and assessing vital rates such as births and deaths are prerequisites for understanding population dynamics. Vital rates may be affected by the density of individuals, even though the importance of density dependence on population dynamics has been debated for a long time. LÄS MER

  3. 2. Paternal care and brood reduction in a pipefish

    Författare :Gry Sagebakken; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Parental care; brood reduction; embryo survival; parental condition; filial cannibalism; post-mating sexual selection; HSI; sexual conflicts; Syngnathus typhle; male brooding;

    Sammanfattning : From an evolutionary and adaptive perspective, the occurrence and extent of parental care in animals (investment in offspring beyond the genetic contribution) is expected to depend on an optimal (fitness-maximizing) balance of its costs and benefits. Males of the sex-role reversed broad-nosed pipefish, Syngnathus typhle, which care for eggs and embryos and may perform brood reduction, are particularly interesting in this respect. LÄS MER

  4. 3. 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

  5. 4. Infidelity in Birds – Causes and Consequences of Extra-pair Paternity

    Författare :Jakob Augustin; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; extra-pair paternity; genetic benefits; heterozygosity; sex ratio; Riparia riparia; Tringa totanus; Vanellus vanellus; Charadrius alexandrinus;

    Sammanfattning : Forty years ago, more than 90% of bird species were classified as monogamous and not very exciting systems for studies of e.g. sexual selection. LÄS MER

  7. 5. Female Reproductive Strategies in the Ruff (Philomachus pugnax)

    Författare :Katherine Thuman; Fredrik Widemo; Robert Montgommery; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi; Animal Ecology; zooekologi;

    Sammanfattning : Traditionally, females have been considered to be strictly monogamous. Today, we know that females in the majority of species actively seek out and mate with several males. Trying to understand female preferences, including what benefits mate choice entails, has been the focus of intense research during the last decades. LÄS MER