Asbjørn Vøllestad - Academia.edu (original) (raw)

Papers by Asbjørn Vøllestad

Research paper thumbnail of Within-species variation in the gut microbiome of medaka (Oryzias latipes) is driven by the interaction of light intensity and genetic background

Peer Community Journal, Aug 20, 2023

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Editorial 2024

Ecology of Freshwater Fish, Oct 25, 2023

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Limnologisk og fiskeribiologisk undersøkelse av Einafjorden sommeren 1995. (Investigations of limnology and fish biology in lake Einafjord summer 1995)

Sommeren 1995 ble det i Einafjorden utført limnologiske og fiskeribiologiske undersøkelser samt r... more Sommeren 1995 ble det i Einafjorden utført limnologiske og fiskeribiologiske undersøkelser samt registrering av vannvegetasjon. Resultatene fra disse undersøkelser er jevnført med tidligere undersøkelser fra perioden 1977 - 1991. Undersøkelsen i 1995 viste at det hadde skjedd store forandringer i krepsdyreplankton- og fiskesamfunnet. Krepsdyrene er nå utsatt for stort beitepress fra fisk. Gjedde har kommet inn i innsjøen og etablert et rikt bestand, og røyen er på vei ut. Sik og krøkle har endret habitat. Videre har det kommet vasspest til Einafjorden som nå etablert bestander langs hele innsjøen. Det var små forandringer i vannkvaliteten. Innsjøen har fortsatt et klart oligotroft (næringsfattig) preg med relativt lave fosfor- og planteplanktonkonsentrasjoner. Nitrogeninnholdet er likevel fortsatt høyt og klart overstigende de naturgitte forhold. Arealavrenning fra omkringliggende jorder antas å være den største nitrogenkilden. Det er viktig å følge utviklingen i Einafjorden. Hard beskatning av gjedde og sik foreslås som tiltak for å kunne berge røyen. Videre er det ønskelig at fosfor- og særlig nitrogentilførselen ytterlige reduseres bl.a. ved tiltak som endret jordbearbeiding og endrede gjødselrutiner. Punktutslipp som boligkloakk og utsig fra gjødselkjellere og silonedleggelse må også kontrolleres.Vestre Toten kommun

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Modularity Facilitates Flexible Tuning Of Plastic And Evolutionary Gene Expression Responses During Early Divergence

Gene expression changes have been recognized as important drivers of adaptation to changing envir... more Gene expression changes have been recognized as important drivers of adaptation to changing environmental conditions. Little is known about the relative roles of plastic and evolutionary responses in complex gene expression networks during the early stages of divergence. Large gene expression data sets coupled with in silico methods for identifying co-expressed modules now enable systems genetics approaches also in non-model species for better understanding of gene expression responses during early divergence. Here, we combined gene co-expression analyses with population genetics to separate plastic and population (evolutionary) effects in expression networks using small salmonid populations as a model system. We show that plastic and population effects were highly variable among the six identified modules and that the plastic effects explained larger proportion of the total eigengene expression than population effects. A more detailed analysis of the population effects using a QST ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Mechanistic Evaluation of Brown Trout Performance Across Their Native and Exotic Habitat: Lessons Fro Managing Invasive Trout

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Within-species variation in the gut microbiome of medaka (Oryzias latipes) is driven by the interaction of light intensity and genetic background

Unravelling evolution-by-environment interactions on the gut microbiome is particularly relevant ... more Unravelling evolution-by-environment interactions on the gut microbiome is particularly relevant considering the unprecedented level of human-driven disruption of the ecological and evolutionary trajectories of species. Here, we aimed to evaluate whether an evolutionary response to size-selective mortality influences the gut microbiome of medaka (Oryzias latipes), how environmental conditions interact with the genetic background of medaka on their microbiota, and the association between microbiome diversity and medaka growth-related traits. To do so, we studied two lineages of medaka with known divergence in foraging efficiency and life history raised under antagonistic size-selective regimes for 10 generations (i.e. the largest or the smallest breeders were removed to mimic fishing-like or natural mortality). In pond mesocosms, the two lineages were subjected to contrasting population density and light intensity (used as proxies of resource availability). We observed significant di...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Editorial 2023

Ecology of Freshwater Fish

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Density-dependent consequences of size-selective induced life-history changes to population fitness in medaka (Oryzias latipes)

Canadian Journal of Fisheries and Aquatic Sciences, 2020

There is an increasing concern about the potential for size-selective harvest to impair populatio... more There is an increasing concern about the potential for size-selective harvest to impair population persistence. Yet little is known about the relative contribution of the evolutionary (shifts in life history) and demographic effects (decreased population density and size truncation) of harvesting to changes in fitness. Using medaka (Oryzias latipes), we experimentally investigated the fitness consequences of antagonistic size-dependent selection under contrasted levels of density (low versus high) and size structure (uniform versus truncated). The size-dependent selection generated large- and small-breeder lines with fast growth and late maturity versus slow growth and early maturity life histories, respectively. A decrease in density had a positive effect on almost all fitness components, while size truncation only had a positive effect on fish growth. Small-breeder fish grew slower and had a greater probability of reproducing, at least when considering small-sized females. The num...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Forekomsten av havniøye i norske elver

23, 2021

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Atlantic Salmon Variability: The Effects of Ocean, Freshwater and Human Impacts Using Multiple Time-Series of Rod Catches from Norwegian and Scottish Rivers

participantAtlantic salmon (Salmo salar) fishing is one of the most important recreational fisher... more participantAtlantic salmon (Salmo salar) fishing is one of the most important recreational fisheries in both Norway and Scotland and it has become an important factor in outdoor activities, with salmon angling estimated annual value to be approximately 1 billion NOK in Norway and £70 million in Scotland. The Atlantic salmon is a charismatic anadromous fish utilizing freshwater habitats for spawning and early development, and marine habitats for its main somatic growth. This species is fairly long-lived and is exposed to a large number of human encroachments both in freshwaters and in the sea. It has experienced strong declines worldwide during the last century, although many viable populations remain in the central and northern parts of the species' range. The largest component of natural mortality in the marine environment occurs during the first year at sea, indeed, survival has often been associated with sea surface temperature, which presumably modulates growth rates and controls recruitment. Moreover, yearly fluctuations of one-sea-winter fish are related with sea temperature. Furthermore, the current ocean warming in the foraging areas contributes to delay maturation and decreases growth conditions. In addition, local extinction or strong reductions in production have been partly attributed to acidification and other kinds of pollution, damming, exotic parasites and the effects of increased aquaculture. Understanding the complexity on how within and among river factors affect the dynamics of Atlantic salmon populations will improve our ability to manage the wild resource effectively in the face of current changes in environmental trends

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A critical review of adaptive genetic variation in Atlantic salmon: implications for conservation

Biological Reviews, 2007

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Status of wild Atlantic salmon in Norway

The committee is appointed by the Norwegian Environment Agency. The mission of the committee is t... more The committee is appointed by the Norwegian Environment Agency. The mission of the committee is to evaluate status of salmon and the relative importance of different threat factors, give science-based catch advice and give advice on other subjects related to wild salmon management. The committee only gives advice related to biological questions, and do not consider socio-economic challenges in the management of salmon.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Slektskap og kolonisering hos ørekyt

Målet med dette prosjektet var å studere populasjonsgenetikken til ørekyt i Norge med sikte på å ... more Målet med dette prosjektet var å studere populasjonsgenetikken til ørekyt i Norge med sikte på å få økt kunnskap om artens spredningsmekanismer. Ørekyten utvider stadig sitt leveområde, og det er uklart hvordan spredningen skjer. Vi har kunnet fastslå at noen av ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Cross-Continental, Comparison of Factors Limiting the Endemic and Exotic Distribution of Brown Trout: How Can Estimating Bioenergetic Efficiency Inform Management and Conservation?

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Kan Gyrodactylus salaris utryddes fra Drammensregionen? Sluttrapport fra arbeidsgruppen for Drammensregionen

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Latitudinal Variation in Life-History Traits in Eurasian Perch

Ecology, 2005

Few studies have examined multiple life-history traits across a latitudinal gradient to test whet... more Few studies have examined multiple life-history traits across a latitudinal gradient to test whether variation in growth rate and mortality schedules induces trends predicted by life-history theory. We collected data for the following life-history traits for 75 Eurasian perch (Perca ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The ideal free pike: 50 years of fitness-maximizing dispersal in Windermere

… of the Royal …, 2006

The ideal free distribution (IFD) theory is one of the most influential theories in evolutionary ... more The ideal free distribution (IFD) theory is one of the most influential theories in evolutionary ecology. It predicts how animals ought to distribute themselves within a heterogeneous habitat in order to maximize lifetime fitness. We test the population level consequence of the IFD ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Life‐history variation in perch (Perca fluviatilis L.) in five neighbouring Norwegian lakes

Ecology of freshwater Fish, 2002

... tip of the tail when the fish was in a natural position to the nearest millimetres) and mass ... more ... tip of the tail when the fish was in a natural position to the nearest millimetres) and mass (nearest to 0.1 g), and assigned sex and maturation ... A low female age at maturity in perch may be a response to environmental stress (eg, water level regulation (Stehlík 1968; Chappaz et al ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Status of wild Atlantic salmon in Norway 2018

Thirteen scientists from seven different institutes/universities are members of the committee: To... more Thirteen scientists from seven different institutes/universities are members of the committee: Torbjørn Forseth (leader), Bjørn T. Barlaup, Sigurd Einum, Bengt Finstad, Peder Fiske, Morten Falkegård, Åse Helen Garseth, Atle Hindar, Tor Atle Mo, Eva B. Thorstad, Kjell Rong Utne, Asbjørn Vøllestad and Vidar Wennevik. The committee is an independent body, and the members do not represent the institutions where they are employed when serving on the committee.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Six decades of pike and perch population dynamics in Windermere

Fisheries Research, Feb 2, 2011

We use six decades of catch-at-age data for perch (Perca fluviatilis) and pike (Esox lucius) in W... more We use six decades of catch-at-age data for perch (Perca fluviatilis) and pike (Esox lucius) in Windermere (UK) to estimate age-and sex-specific population sizes, natural mortalities and catchabilities in both species. Population sizes are estimated by fitting age structured population models to the catch-at-age data using standard maximum likelihood methods. We validate our methods using data simulations, and use our estimates of vital rates (natural mortality, recruitment and catahability) to address important aspects of fisheries biology. ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Within-species variation in the gut microbiome of medaka (Oryzias latipes) is driven by the interaction of light intensity and genetic background

Peer Community Journal, Aug 20, 2023

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Editorial 2024

Ecology of Freshwater Fish, Oct 25, 2023

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Limnologisk og fiskeribiologisk undersøkelse av Einafjorden sommeren 1995. (Investigations of limnology and fish biology in lake Einafjord summer 1995)

Sommeren 1995 ble det i Einafjorden utført limnologiske og fiskeribiologiske undersøkelser samt r... more Sommeren 1995 ble det i Einafjorden utført limnologiske og fiskeribiologiske undersøkelser samt registrering av vannvegetasjon. Resultatene fra disse undersøkelser er jevnført med tidligere undersøkelser fra perioden 1977 - 1991. Undersøkelsen i 1995 viste at det hadde skjedd store forandringer i krepsdyreplankton- og fiskesamfunnet. Krepsdyrene er nå utsatt for stort beitepress fra fisk. Gjedde har kommet inn i innsjøen og etablert et rikt bestand, og røyen er på vei ut. Sik og krøkle har endret habitat. Videre har det kommet vasspest til Einafjorden som nå etablert bestander langs hele innsjøen. Det var små forandringer i vannkvaliteten. Innsjøen har fortsatt et klart oligotroft (næringsfattig) preg med relativt lave fosfor- og planteplanktonkonsentrasjoner. Nitrogeninnholdet er likevel fortsatt høyt og klart overstigende de naturgitte forhold. Arealavrenning fra omkringliggende jorder antas å være den største nitrogenkilden. Det er viktig å følge utviklingen i Einafjorden. Hard beskatning av gjedde og sik foreslås som tiltak for å kunne berge røyen. Videre er det ønskelig at fosfor- og særlig nitrogentilførselen ytterlige reduseres bl.a. ved tiltak som endret jordbearbeiding og endrede gjødselrutiner. Punktutslipp som boligkloakk og utsig fra gjødselkjellere og silonedleggelse må også kontrolleres.Vestre Toten kommun

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Modularity Facilitates Flexible Tuning Of Plastic And Evolutionary Gene Expression Responses During Early Divergence

Gene expression changes have been recognized as important drivers of adaptation to changing envir... more Gene expression changes have been recognized as important drivers of adaptation to changing environmental conditions. Little is known about the relative roles of plastic and evolutionary responses in complex gene expression networks during the early stages of divergence. Large gene expression data sets coupled with in silico methods for identifying co-expressed modules now enable systems genetics approaches also in non-model species for better understanding of gene expression responses during early divergence. Here, we combined gene co-expression analyses with population genetics to separate plastic and population (evolutionary) effects in expression networks using small salmonid populations as a model system. We show that plastic and population effects were highly variable among the six identified modules and that the plastic effects explained larger proportion of the total eigengene expression than population effects. A more detailed analysis of the population effects using a QST ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Mechanistic Evaluation of Brown Trout Performance Across Their Native and Exotic Habitat: Lessons Fro Managing Invasive Trout

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Within-species variation in the gut microbiome of medaka (Oryzias latipes) is driven by the interaction of light intensity and genetic background

Unravelling evolution-by-environment interactions on the gut microbiome is particularly relevant ... more Unravelling evolution-by-environment interactions on the gut microbiome is particularly relevant considering the unprecedented level of human-driven disruption of the ecological and evolutionary trajectories of species. Here, we aimed to evaluate whether an evolutionary response to size-selective mortality influences the gut microbiome of medaka (Oryzias latipes), how environmental conditions interact with the genetic background of medaka on their microbiota, and the association between microbiome diversity and medaka growth-related traits. To do so, we studied two lineages of medaka with known divergence in foraging efficiency and life history raised under antagonistic size-selective regimes for 10 generations (i.e. the largest or the smallest breeders were removed to mimic fishing-like or natural mortality). In pond mesocosms, the two lineages were subjected to contrasting population density and light intensity (used as proxies of resource availability). We observed significant di...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Editorial 2023

Ecology of Freshwater Fish

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Density-dependent consequences of size-selective induced life-history changes to population fitness in medaka (Oryzias latipes)

Canadian Journal of Fisheries and Aquatic Sciences, 2020

There is an increasing concern about the potential for size-selective harvest to impair populatio... more There is an increasing concern about the potential for size-selective harvest to impair population persistence. Yet little is known about the relative contribution of the evolutionary (shifts in life history) and demographic effects (decreased population density and size truncation) of harvesting to changes in fitness. Using medaka (Oryzias latipes), we experimentally investigated the fitness consequences of antagonistic size-dependent selection under contrasted levels of density (low versus high) and size structure (uniform versus truncated). The size-dependent selection generated large- and small-breeder lines with fast growth and late maturity versus slow growth and early maturity life histories, respectively. A decrease in density had a positive effect on almost all fitness components, while size truncation only had a positive effect on fish growth. Small-breeder fish grew slower and had a greater probability of reproducing, at least when considering small-sized females. The num...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Forekomsten av havniøye i norske elver

23, 2021

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Atlantic Salmon Variability: The Effects of Ocean, Freshwater and Human Impacts Using Multiple Time-Series of Rod Catches from Norwegian and Scottish Rivers

participantAtlantic salmon (Salmo salar) fishing is one of the most important recreational fisher... more participantAtlantic salmon (Salmo salar) fishing is one of the most important recreational fisheries in both Norway and Scotland and it has become an important factor in outdoor activities, with salmon angling estimated annual value to be approximately 1 billion NOK in Norway and £70 million in Scotland. The Atlantic salmon is a charismatic anadromous fish utilizing freshwater habitats for spawning and early development, and marine habitats for its main somatic growth. This species is fairly long-lived and is exposed to a large number of human encroachments both in freshwaters and in the sea. It has experienced strong declines worldwide during the last century, although many viable populations remain in the central and northern parts of the species' range. The largest component of natural mortality in the marine environment occurs during the first year at sea, indeed, survival has often been associated with sea surface temperature, which presumably modulates growth rates and controls recruitment. Moreover, yearly fluctuations of one-sea-winter fish are related with sea temperature. Furthermore, the current ocean warming in the foraging areas contributes to delay maturation and decreases growth conditions. In addition, local extinction or strong reductions in production have been partly attributed to acidification and other kinds of pollution, damming, exotic parasites and the effects of increased aquaculture. Understanding the complexity on how within and among river factors affect the dynamics of Atlantic salmon populations will improve our ability to manage the wild resource effectively in the face of current changes in environmental trends

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A critical review of adaptive genetic variation in Atlantic salmon: implications for conservation

Biological Reviews, 2007

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Status of wild Atlantic salmon in Norway

The committee is appointed by the Norwegian Environment Agency. The mission of the committee is t... more The committee is appointed by the Norwegian Environment Agency. The mission of the committee is to evaluate status of salmon and the relative importance of different threat factors, give science-based catch advice and give advice on other subjects related to wild salmon management. The committee only gives advice related to biological questions, and do not consider socio-economic challenges in the management of salmon.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Slektskap og kolonisering hos ørekyt

Målet med dette prosjektet var å studere populasjonsgenetikken til ørekyt i Norge med sikte på å ... more Målet med dette prosjektet var å studere populasjonsgenetikken til ørekyt i Norge med sikte på å få økt kunnskap om artens spredningsmekanismer. Ørekyten utvider stadig sitt leveområde, og det er uklart hvordan spredningen skjer. Vi har kunnet fastslå at noen av ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Cross-Continental, Comparison of Factors Limiting the Endemic and Exotic Distribution of Brown Trout: How Can Estimating Bioenergetic Efficiency Inform Management and Conservation?

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Kan Gyrodactylus salaris utryddes fra Drammensregionen? Sluttrapport fra arbeidsgruppen for Drammensregionen

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Latitudinal Variation in Life-History Traits in Eurasian Perch

Ecology, 2005

Few studies have examined multiple life-history traits across a latitudinal gradient to test whet... more Few studies have examined multiple life-history traits across a latitudinal gradient to test whether variation in growth rate and mortality schedules induces trends predicted by life-history theory. We collected data for the following life-history traits for 75 Eurasian perch (Perca ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The ideal free pike: 50 years of fitness-maximizing dispersal in Windermere

… of the Royal …, 2006

The ideal free distribution (IFD) theory is one of the most influential theories in evolutionary ... more The ideal free distribution (IFD) theory is one of the most influential theories in evolutionary ecology. It predicts how animals ought to distribute themselves within a heterogeneous habitat in order to maximize lifetime fitness. We test the population level consequence of the IFD ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Life‐history variation in perch (Perca fluviatilis L.) in five neighbouring Norwegian lakes

Ecology of freshwater Fish, 2002

... tip of the tail when the fish was in a natural position to the nearest millimetres) and mass ... more ... tip of the tail when the fish was in a natural position to the nearest millimetres) and mass (nearest to 0.1 g), and assigned sex and maturation ... A low female age at maturity in perch may be a response to environmental stress (eg, water level regulation (Stehlík 1968; Chappaz et al ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Status of wild Atlantic salmon in Norway 2018

Thirteen scientists from seven different institutes/universities are members of the committee: To... more Thirteen scientists from seven different institutes/universities are members of the committee: Torbjørn Forseth (leader), Bjørn T. Barlaup, Sigurd Einum, Bengt Finstad, Peder Fiske, Morten Falkegård, Åse Helen Garseth, Atle Hindar, Tor Atle Mo, Eva B. Thorstad, Kjell Rong Utne, Asbjørn Vøllestad and Vidar Wennevik. The committee is an independent body, and the members do not represent the institutions where they are employed when serving on the committee.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Six decades of pike and perch population dynamics in Windermere

Fisheries Research, Feb 2, 2011

We use six decades of catch-at-age data for perch (Perca fluviatilis) and pike (Esox lucius) in W... more We use six decades of catch-at-age data for perch (Perca fluviatilis) and pike (Esox lucius) in Windermere (UK) to estimate age-and sex-specific population sizes, natural mortalities and catchabilities in both species. Population sizes are estimated by fitting age structured population models to the catch-at-age data using standard maximum likelihood methods. We validate our methods using data simulations, and use our estimates of vital rates (natural mortality, recruitment and catahability) to address important aspects of fisheries biology. ...

Bookmarks Related papers MentionsView impact