Blar i NTNU Open på forfatter "Ringsby, Thor Harald"
-
Artificial size selection experiment reveals telomere length dynamics and fitness consequences in a wild passerine
Pepke, Michael Le; Kvalnes, Thomas; Rønning, Bernt; Jensen, Henrik; Boner, Winnie; Sæther, Bernt-Erik; Monaghan, Pat; Ringsby, Thor Harald (Peer reviewed; Journal article, 2022)Telomere dynamics could underlie life-history trade-offs among growth, size and longevity, but our ability to quantify such processes in natural, unmanipulated populations is limited. We investigated how 4 years of artificial ... -
Causes and Consequences of Breeding Synchrony in the Snow Bunting (Plectrophenax nivalis )
Skøien, Elida Arstad (Master thesis, 2015)Climate warming is happening rapidly in the Arctic and migratory birds are among the species expected to be affected by the predicted shifts in spring phenology. Using time-series data (1998 - 2014) from a population of ... -
Causes and consequences of variation in early-life telomere length in a bird metapopulation
Pepke, Michael Le; Kvalnes, Thomas; Ranke, Peter Sjolte; Araya-Ajoy, Yimen; Wright, Jonathan; Sæther, Bernt-Erik; Jensen, Henrik; Ringsby, Thor Harald (Peer reviewed; Journal article, 2022)Environmental conditions during early-life development can have lasting effects shaping individual heterogeneity in fitness and fitness-related traits. The length of telomeres, the DNA sequences protecting chromosome ends, ... -
Characterizing morphological (co)variation using structural equation models: Body size, allometric relationships and evolvability in a house sparrow metapopulation
Araya-Ajoy, Yimen; Ranke, Peter Sjolte; Kvalnes, Thomas; Rønning, Bernt; Holand, Håkon; Myhre, Ane Marlene; Pärn, Henrik; Jensen, Henrik; Ringsby, Thor Harald; Sæther, Bernt-Erik; Wright, Jonathan (Peer reviewed; Journal article, 2019)Body size plays a key role in the ecology and evolution of all organisms. Therefore, quantifying the sources of morphological (co)variation, dependent and independent of body size, is of key importance when trying to ... -
Climate trends, weather fluctuations and calving phenology in Svalbard reindeer (Rangifer tarandus platyrhynchus)
Danielsen, Preben (Master thesis, 2016)Reproduction is known to be one of the most energetically demanding processes in the life of an organism, and in seasonal environments, vertebrate offspring production is therefore timed to coincide with the annual peak ... -
Climatic forcing and individual heterogeneity in a resident mountain bird: legacy data reveal effects on reproductive strategies
Eriksen, Lasse Frost; Ringsby, Thor Harald; Pedersen, Hans Christian; Nilsen, Erlend Birkeland (Peer reviewed; Journal article, 2023)Optimization of clutch size and timing of reproduction have substantial effects on lifetime reproductive success in vertebrates, and both individual quality and environmental variation may impact life history strategies. ... -
Controlling for P-value inflation in allele frequency change in experimental evolution and artificial selection experiments
Kemppainen, Petri; Rønning, Bernt; Kvalnes, Thomas; Hagen, Ingerid Julie; Ringsby, Thor Harald; Billing, Anna Maria; Pärn, Henrik; Lien, Sigbjørn; Husby, Arild; Sæther, Bernt-Erik; Jensen, Henrik (Journal article; Peer reviewed, 2017)Experimental evolution studies can be used to explore genomic response to artificial and natural selection. In such studies, loci that display larger allele frequency change than expected by genetic drift alone are assumed ... -
Demographic and genetic consequences of dispersal in house sparrows
Ranke, Peter Sjolte (Doctoral theses at NTNU;2019:24, Doctoral thesis, 2019)The importance of dispersal in population dynamics is widely acknowledged. Key to understand population consequences of dispersal is by quantifying the demographic and genetic contribution from dispersers. The influence ... -
Demographic determinants of population growth rate in willow ptarmigan (Lagopus lagopus) in Lierne, central Norway
Stavnås, Veronica Myhr (Master thesis, 2018)Willow ptarmigan (Lagopus lagopus) populations in Norway have declined during the last decade and the species was included in the Norwegian Red list in 2015 as near threatened . Accordingly, it is important to identify ... -
Demographic influences of translocated individuals on a resident population of house sparrows
Ranke, Peter Sjolte; Skjelseth, Sigrun; Pärn, Henrik; Herfindal, Ivar; Borg Pedersen, Åsa Alexandra; Stokke, Bård Gunnar; Kvalnes, Thomas; Ringsby, Thor Harald; Sæther, Bernt-Erik; Jensen, Henrik (Journal article; Peer reviewed, 2017)Translocation of individuals from source populations to augment small populations facing risk of extinction is an important conservation tool. Here we examine sex-specific differences between resident and translocated house ... -
Disentangling the age-dependent causal pathways affecting multiple paternity in house sparrows
Søraker, Jørgen Skavdal (Master thesis, 2022)De drivende mekanismene bak fordelingen av polygami hos sosialt monogame fuglearter har fått mye oppmerksomhet de siste tiårene. Alder og morfologi, og særlig sekundære seksuelle trekk, har ofte blitt pekt på som viktige ... -
Dispersal in a house sparrow metapopulation: An integrative case study of genetic assignment calibrated with ecological data and pedigree information
Saatoglu, Fikriye Dilan; Niskanen, Alina Katariina; Kuismin, Markku; Ranke, Peter Sjolte; Hagen, Ingerid Julie; Araya-Ajoy, Yimen; Kvalnes, Thomas; Pärn, Henrik; Rønning, Bernt; Ringsby, Thor Harald; Sæther, Bernt-Erik; Husby, Arild; Sillanpää, Mikko J.; Jensen, Henrik (Peer reviewed; Journal article, 2021)Dispersal has a crucial role determining ecoevolutionary dynamics through both gene flow and population size regulation. However, to study dispersal and its consequences, one must distinguish immigrants from residents. ... -
The ecological and evolutionary role of telomere length in house sparrows
Pepke, Michael Le (Doctoral theses at NTNU;2021:420, Doctoral thesis, 2021)Telomeres, the DNA sequences capping the ends of linear chromosomes, are ancient molecular structures that are shared among most eucaryotes. The telomeres protect chromosomes from degradation and are vital to genome ... -
“Effect of inbreeding on egg size and clutch size in an insular house sparrow metapopulation in northern Norway”
Gholami, Fatemeh (Master thesis, 2023)Innavlsdepresjon er en av de største truslene mot overlevelsen til små, isolerte bestander. For å få en fullstendig forståelse av innavlens innvirkning på populasjonens levedyktighet er det nødvendig å kvantifisere ... -
Effects of arthropod abundance on reproductive success in Svalbard snow bunting (Plectrophenax nivalis)
Gravelsæther, Maria Angelil (Master thesis, 2021)Arktisk oppvarming fører til store miljøforandringer og biologiske forandringer, samt påvirker trofiske interaksjoner. Effekter av klimaforandringer har allerede blitt observert hos flere arktis-hekkende trekkfugler, med ... -
Effects of inbreeding on lay date in house sparrows (Passer domesticus)
Muller, Amandine Sophie (Master thesis, 2021)Innavlsdepresjon (en reduksjon i individuell fitness forårsaket av innavl) har blitt observert hos mange ulike arter, men mekanismene som gir innavlsdepresjon er fremdeles uklare. Innavl og innavlsdepresjon studeres vanligvis ... -
Effects of population characteristics and structure on estimates of effective population size in a house sparrow metapopulation
Baalsrud, Helle Tessand; Sæther, Bernt-Erik; Hagen, Ingerid Julie; Myhre, Ane Marlene; Ringsby, Thor Harald; Pärn, Henrik; Jensen, Henrik (Journal article, 2014)Effective population size (Ne) is a key parameter to understand evolutionary processes and the viability of endangered populations as it determines the rate of genetic drift and inbreeding. Low Ne can lead to inbreeding ... -
Effects of Variation in Egg Size on Maternal Fitness in a Population of House Sparrows (Passer domesticus)
Krogfjord, Mari (Master thesis, 2018)According to life history theory individuals will optimize investment into growth, reproduction and self-maintenance. Egg size is an important life history trait predicted to have an optimum that maximizes maternal individual ... -
Effects of Variation in Egg Size on Offspring Fitness in Populations of House Sparrow (Passer domesticus)
Røberg, Anja Ås (Master thesis, 2015)1. Egg size represents an important life-history trait, which may have effects on the fitness of offspring. The effect of variation in egg size on offspring fitness has been studied within many taxa, but there is still a ... -
Endoparasite infection has both short- and long-term negative effects on reproductive success of female house sparrows, as revealed by faecal parasitic egg counts
Holand, Håkon; Jensen, Henrik; Tufto, Jarle; Pärn, Henrik; Sæther, Bernt-Erik; Ringsby, Thor Harald (Journal article; Peer reviewed, 2015)Parasites have the potential to severely reduce host reproductive success. However, the effects of endoparasites on reproductive success have not received the same amount of attention as the effects of parasites on host ...