Sökning: "Egg size"

Visar resultat 1 - 5 av 45 avhandlingar innehållade orden Egg size.

1. 1. 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

3. 2. Ontogenetic scaling and the development of within-cohort size structure

   Författare :Magnus Huss; Lennart Persson; Pär Byström; David Post; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; cannibalism; competition; density-dependence; resource feedbacks; hatching; growth; ontogenetic niche shifts; Perca fluviatilis; size variation; larval fish; Freshwater ecology; Limnisk ekologi; zooekologi; Animal Ecology;

   Sammanfattning : It is increasingly recognized that individuals of the same species differ from each other and influence and respond to their environment in unique ways. This thesis deals with size variation among individuals that not only are of the same species but also of similar age. LÄS MER

4. 3. Reproductive pattern and offspring performance in brown trout (Salmo trutta)

   Författare :Hans Olofsson; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology; Salmo trutta; spawning; egg size; fry competition; fry dispersion; Biologi; Biology; Biologi; limnologi; Limnology;

   Sammanfattning : This thesis deals with how reproductive traits and reproductive behaviour in femalebrown trout (Salmo trutta) are linked to offspring performance.In the small stream Tullviksbäcken, the choice of spawning sites was stronglyinfluenced by short-term fluctuations in stream flow and by substrate quality. LÄS MER

5. 4. Development and maintenance of quality indicators in pheasants

   Författare :Thomas Ohlsson; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; PHA; ELISA; immunocompetence; carotenoid coloration; male ornaments; fluctuating asymmetry; growth; early development; Phasianus colchicus; egg size; sexual selection; Animal ecology; Djurekologi; Ecology; Ekologi;

   Sammanfattning : Females often base their choice of mates on the expression, size or intensity, of male sexual ornaments. Indicator models of sexual selection assume that females assess male genetic quality through the expression of these secondary sexual characters. LÄS MER

7. 5. Effects of abiotic and biotic factors on hatching, emergence and survival in Baltic salmon (Salmo salar L.)

   Författare :Eva Brännäs; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Baltic salmon; salmo salar; eggs; egg colour; alevins; fry; photoperiod; temperature; hatching; emergence pattern; synchronization; survival;

   Sammanfattning : This thesis deals with important factors that affect the temporal organization of emergence and early survival of Baltic salmon (Salmo salar L.). The study population was obtained from the Norrfors hatchery (63°50'N,20°05'E), Umeälven (Ume river) in Northern Sweden. LÄS MER