Large-effect loci mediate rapid adaptation of salmon body size after river regulation.

Understanding the potential of natural populations to adapt to altered environments is becoming increasingly relevant in evolutionary research. Currently, our understanding of adaptation to human alteration of the environment is hampered by lack of knowledge on the genetic basis of traits, lack of time series, and little or no information on changes in optimal trait values. Here, we used time series data spanning nearly a century to investigate how the body mass of Atlantic salmon () adapts to river regulation.

Effects of Episodic Exposure to High-pH Water on Survival of Atlantic Salmon Eggs and Juveniles: Results from Laboratory and Field Studies.

Although effects of acidification on salmonid fish are well studied and documented, effects of episodic high pH have rarely received attention. In the present study, we investigated effects of high-pH events on Atlantic salmon (Salmo salar) using both field and laboratory data. Effects of an episodic high-pH event on juvenile densities in a Norwegian river were studied using data from several electrofishing surveys conducted both before and after the event.

Passing a seawater challenge test is not indicative of hatchery-reared Atlantic salmon Salmo salar smolts performing as well at sea as their naturally produced conspecifics.

Despite satisfactory reactions to seawater challenge tests indicative of appropriate physiological state, hatchery-reared Atlantic salmon Salmo salar smolts stocked in the Eira River in Norway between 2001 and 2011 performed less well at sea in terms of growth, age at maturity and survival than smolts of natural origin. The mean rates of return to the river for hatchery-reared and naturally produced S. salar were 0·98 and 2·35%.

Multilocus heterozygosity and inbreeding depression in an insular house sparrow metapopulation.

Inbreeding causes reduction of genetic variability that may have severe fitness consequences. In spite of its potentially huge impact on viability and evolutionary processes especially in small populations, quantitative demonstrations of genetic and demographic effects of inbreeding in natural populations are few. Here, we examine the relationship between individual inbreeding coefficients (F) and individual standardized multilocus heterozygosity (H) in an insular metapopulation of house sparrows (Passer domesticus) in northern Norway in order to evaluate whether H is a good predictor for F.

Three-dimensional microhabitat use by young pool-dwelling Atlantic salmon and brown trout.

This study, conducted in deep pools in three rivers, is the first to show a clear three-dimensional habitat segregation in size groups (equivalent to age groups) of juvenile Atlantic salmon, Salmo salar, and brown trout, S. trutta. Young-of-the-year (YOY) held position near the river bed and the river bank; height above bottom and distance from river bank increased significantly with fish size.