Sökning: "arctic char"

Visar resultat 1 - 5 av 9 avhandlingar innehållade orden arctic char.

1. 1. Evolutionary ecology of arctic char (Salvelinus alpinus (L.)) : Intra- and interspecific interactions in circumpolar populations

   Författare :Johan Hammar; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; Arctic char; Salvelinus alpinus; biogeography; niche; life history; population ecology; intra- and interspecific interactions; cannibalism; competition; landlocked; marginal populations; species border; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi; Animal Ecology; zooekologi;

   Sammanfattning : This thesis examines a suite of ecological and genetic mechanisms influencing the fundamental and realized niche borders of European and North American populations of the Arctic char (Salvelinus alpinus (L.)) species complex in allopatry as well as in sympatry with brown trout (Salmo trutta) or brook trout (Salvelinus fontinalis). LÄS MER

3. 2. Invasion of top and intermediate consumers in a size structured fish community

   Författare :Per Ask; Lennart Persson; Daniel E Schindler; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Invasion; intraguild predation; size-structure; cannibalism; climate; temperature; Arctic char; ninespine stickleback; Freshwater ecology; Limnisk ekologi; biology; biologi;

   Sammanfattning : In this thesis I have investigated the effects of invading top and intermediate consumers in a size-structured fish community, using a combination of field studies, a lake invasion experiment and smaller scale pond and aquaria experiments. The lake invasion experiment was based on introductions of an intermediate consumer, ninespine stickleback (Pungitius pungitius L. LÄS MER

4. 3. Lake bathymetry as driver of salmonid population size structure and biomass

   Författare :Sven Norman; Pär Byström; Karin A. Nilsson; Jan Karlsson; Per-Arne Amundsen; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Lake bathymetry; habitat-specific resource production; ontogenetic niche shifts; size structure; Arctic char; brown trout; populationsbiologi; Population Biology; Limnology; limnologi; zooekologi; Animal Ecology;

   Sammanfattning : Most fish species undergo ontogenetic niche shifts from feeding on pelagic zooplankton, to larger benthic invertebrates and in some cases also to fish. These ontogenetic niche shifts have strong impact on the interactions within and between species, with effects on individual growth, population abundance and food web dynamics. LÄS MER

5. 4. Developmental and reproductive regulation of NR5A genes in teleosts

   Författare :Jonas von Hofsten; Per-Erik Olsson; Gregory Kelly; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Cell and molecular biology; FTZ-F1; NR5A; zebrafish; teleost; arctic char; SF-1; LRH-1; fushi tarazu; Cell- och molekylärbiologi; Cell and molecular biology; Cell- och molekylärbiologi; molekylärbiologi; Molecular Biology;

   Sammanfattning : In mammals sex chromosomes direct and initiate the development of male and female gonads and subsequently secondary sex characteristics. In most vertebrates each individual is pre-destined to either become male or female. LÄS MER

7. 5. Teleost reproduction: Aspects of Arctic char (Salvelinus alpinus) oocyte growth and maturation

   Författare :Håkan Berg; Per-Erik Olsson; Birgitta Norberg; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Zoophysiology; Salmonid; oocyte growth; vitellogenin; vitelline envelope protein; stress; cortisol; oocyte maturation; membrane receptor; Zoofysiologi; Animal physiology; Zoofysiologi; Zoophysiology; zoofysiologi;

   Sammanfattning : In all vertebrate species, reproduction is a hormonally controlled process, important for growth and maturation of gonads and germ cells. Production of functional germ cells is of outmost importance to secure the survival of a species. Fish comprises 50% of the known vertebrates and are found in aquatic habitats all over the world. LÄS MER