We explore the long-term developments in population biology and life history during the invasion and establishment of the fish species vendace Coregonus albula in a subarctic watercourse by comparing life-history traits and molecular genetic estimates between the source and the colonist population. The two populations exhibited highly contrasting life-history strategies. Relative to the source ...

In adaptive radiations, ecological opportunity (i.e. niche availability) is considered to be an important driver to increase phenotypic variation, but diversity may also be constrained by historical factors related to colonization events. How do ecological opportunity and post-glacial colonization history affect the phenotypic diversity in a young species lineage? We quantified phenotypic diversity ...

Introduced species can alter the topology of food webs. For instance, an introduction can aid the arrival of free-living consumers using the new species as a resource, while new parasites may also arrive with the introduced species. Food-web responses to species additions can thus be far more complex than anticipated. In a subarctic pelagic food web with free-living and parasitic species, two fish ...

Overbefolka fiskebestander er et stort problem i mange av våre innsjøer. Det typiske kjennetegnet er en stor tetthet av gammel, småvokst og mager fisk, gjerne med en høy infeksjon av parasitter. Hardt uttynningsfiske har vært foreslått som et mulig botemiddel, men selv om det har vært gjort mange forsøk på å komme problemet til livs, er det få som har lyktes. Denne rapporten ...

Prey preference of top predators and energy flow across habitat boundaries are of fundamental importance for structure and function of aquatic and terrestrial ecosystems, as they may have strong effects on production, species diversity, and food-web stability. In lakes, littoral and pelagic food-web compartments are typically coupled and controlled by generalist fish top predators. However, the ...

Morphological divergence was evident among three sympatric morphs of Arctic charr (Salvelinus alpinus (L.)) that are ecologically diverged along the shallow-, deep-water resource axis in a subarctic postglacial lake (Norway). The two deep-water (profundal) spawning morphs, a benthivore (PB-morph) and a piscivore (PP-morph), have evolved under identical abiotic conditions with constant low light ...

Pasvikvassdraget har siden 1991 vært gjenstand for omfattende økologiske studier i regi av Ferskvannsøkologisk faggruppe ved Universitetet i Tromsø. Undersøkelsene har særlig vært rettet mot å undersøke effektene av at lagesilda, en fremmed fiskeart for Nord-Norge, kom inn i vassdraget på slutten av 1980-tallet. For å få en grundig forståelse av økologien i vassdraget har studiene også omfattet ...

Parallel phenotypic evolution occurs when independent populations evolve similar traits in response to similar selective regimes. However, populations inhabiting similar environments also frequently show some phenotypic differences that result from non-parallel evolution. In this study, we quantified the relative importance of parallel evolution to similar foraging regimes and nonparallel lake-specific ...

Species interactions can influence ecosystem functioning by enhancing or suppressing the activities of species that drive ecosystem processes, or by causing changes in biodiversity. However, one important class of species interactions – parasitism – has been little considered in biodiversity and ecosystem functioning (BD-EF) research. Parasites might increase or decrease ecosystem processes by ...

The new data on the parasites fauna of the Lake Kronotskoe sympatric charr forms (genus Salvelinus (Nilsson) Richardson, 1836) is presented. Parasites fauna of Bigmouth and Smallmouth charr forms are described for the first time. The information about Longhead charr, Nosed charr and White charr parasites is added. 29 species of parasites from 9 classes were found: Oligohymenophorea, Myxosporåà, ...