Sökning: "brood sex ratio"

Hittade 3 avhandlingar innehållade orden brood 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. 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

  4. 3. Egg size evolution and paternal care in pipefishes

    Författare :Inês Braga Gonçalves; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Egg size; embryo development; embryo survival; hypoxia; male quality; mate choice; mating constraints; oxygen; parental care; parental effects; paternal care; reproductive compensation; sex-role reversal; sexual conflict; Syngnathidae; Syngnathus typhle;

    Sammanfattning : In this thesis I explore how sexual selection, sexual conflicts, coevolution with parental care and an environmental selective agent (hypoxia) affect the evolution of different egg characteristics and embryo survival and size in pipefishes (Syngnathidae). In the broad-nosed pipefish, Syngnathus typhle Linnaeus, both sexes prefer to mate with large partners; large females produce more and larger eggs and large males can care for more young, and, as shown in this thesis, invest more per embryo and provide better oxygenation during brooding. LÄS MER