Browsing NTNU Open by Author "Holand, Håkon"
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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 ... -
Effects of an Offshore Eind Farm (OFW) on the Common Shore Crab Carcinus maenas: Tagging Pilot Experiments in the Lillegrund Offshore Wind Farm (Sweden).
Langhamer, Olivia; Holand, Håkon; Rosenqvist, Gunilla (Journal article; Peer reviewed, 2016)Worldwide growth of offshore renewable energy production will provide marine organisms with new hard substrate for colonization in terms of artificial reefs. The artificial reef effect is important when planning offshore ... -
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 ... -
Infection by a helminth parasite is associated with changes in DNA methylation in the house sparrow
Lundregan, Sarah; Mäkinen, Hannu; Buer, Amberly; Holand, Håkon; Jensen, Henrik; Husby, Arild (Peer reviewed; Journal article, 2022)Parasites can exert strong selective pressures on their hosts and influence the evolution of host immunity. While several studies have examined the genetic basis for parasite resistance, the role of epigenetics in the ... -
Inferences of genetic architecture of bill morphology in house sparrow using a high-density SNP array point to a polygenic basis
Lundregan, Sarah; Hagen, Ingerid Julie; Gohli, Jostein; Niskanen, Alina Katariina; Kemppainen, Petri; Ringsby, Thor Harald; Kvalnes, Thomas; Pärn, Henrik; Rønning, Bernt; Holand, Håkon; Ranke, Peter Sjolte; Båtnes, Anna Solvang; Selvik, Linn-Karina M.; Lien, Sigbjørn; Sæther, Bernt-Erik; Husby, Arild; Jensen, Henrik (Journal article; Peer reviewed, 2018)Understanding the genetic architecture of quantitative traits can provide insights into the mechanisms driving phenotypic evolution. Bill morphology is an ecologically important and phenotypically variable trait, which is ... -
Lower survival probability of house sparrows severely infected by the gapeworm parasite
Holand, Håkon; Jensen, Henrik; Tufto, Jarle; Soliman, Mustafa M.; Pärn, Henrik; Sæther, Bernt-Erik; Ringsby, Thor Harald (Journal article; Peer reviewed, 2014)The effect of parasites in natural populations has received increasing attention in recent years. Studies have shown that parasites may play an important part in population ecology due to their potential effects on host ... -
Offspring fitness and the optimal propagule size in a fluctuating environment
Kvalnes, Thomas; Røberg, Anja Ås; Jensen, Henrik; Holand, Håkon; Pärn, Henrik; Sæther, Bernt-Erik; Ringsby, Thor Harald (Journal article; Peer reviewed, 2018) -
On being the right size: Increased body size is associated with reduced telomere length under natural conditions
Ringsby, Thor Harald; Jensen, Henrik; Pärn, Henrik; Kvalnes, Thomas; Boner, Winnie; Gillespie, Robert; Holand, Håkon; Hagen, Ingerid Julie; Rønning, Bernt; Sæther, Bernt-Erik; Monaghan, Pat (Journal article, 2015)Evolution of body size is likely to involve trade-offs between body size, growth rate and longevity. Within species, larger body size is associated with faster growth and ageing, and reduced longevity, but the cellular ... -
Parasite prevalence increases with temperature in an avian metapopulation in northern Norway
Holand, Håkon; Jensen, Henrik; Kvalnes, Thomas; Tufto, Jarle; Pärn, Henrik; Sæther, Bernt-Erik; Ringsby, Thor Harald (Peer reviewed; Journal article, 2019)Climate and weather conditions may have substantial effects on the ecology of both parasites and hosts in natural populations. The strength and shape of the effects of weather on parasites and hosts are likely to change ... -
Reversal of response to artificial selection on body size in a wild passerine bird
Kvalnes, Thomas; Ringsby, Thor Harald; Jensen, Henrik; Hagen, Ingerid Julie; Rønning, Bernt; Pärn, Henrik; Holand, Håkon; Engen, Steinar; Sæther, Bernt-Erik (Journal article, 2017)A general assumption in quantitative genetics is the existence of an intermediate phenotype with higher mean individual fitness in the average environment than more extreme phenotypes. Here we investigate the evolvability ... -
Sensitivity analysis of effective population size to demographic parameters in house sparrow populations
Stubberud, Marlene Wæge; Myhre, Ane Marlene; Holand, Håkon; Kvalnes, Thomas; Ringsby, Thor Harald; Sæther, Bernt-Erik; Jensen, Henrik (Journal article, 2017)The ratio between the effective and the census population size, (math formula), is an important measure of the long-term viability and sustainability of a population. Understanding which demographic processes that affect ... -
Spatial and temporal variation in hippoboscid parasitism by Ornithomya chloropus on house sparrows (Passer domesticus) and its effect on survival
Vastveit, Helene Russell (Master thesis, 2013)1. I examined how the Hippoboscidae Ornithomya chloropus is spatially and temporally distributed in an insular metapopulation of house sparrows in northern Norway from 2004-2011, whether there were demographic differences ... -
Spatial variation in senescence rates in a bird metapopulation
Holand, Håkon; Kvalnes, Thomas; Gamelon, Marlène; Tufto, Jarle; Jensen, Henrik; Pärn, Henrik; Ringsby, Thor Harald; Sæther, Bernt-Erik (Journal article, 2016)Investigating factors which affect the decline in survival with age, i.e. actuarial senescence, is important in order to understand how demographic rates vary in wild populations. Although the evidence for the occurrence ... -
Stabilizing selection and adaptive evolution in a combination of two traits in an arctic ungulate
Holand, Håkon; Kvalnes, Thomas; Røed, Knut; Holand, Øystein; Sæther, Bernt-Erik; Kumpula, Jukka (Journal article; Peer reviewed, 2020)Stabilizing selection is thought to be common in wild populations and act as one of the main evolutionary mechanisms, which constrain phenotypic variation. When multiple traits interact to create a combined phenotype, ... -
Temporal and spatial variation in prevalence of the parasite Syngamus trachea in a metapopulation of House Sparrows (Passer domesticus)
Holand, Håkon; Jensen, Henrik; Tufto, Jarle; Sæther, Bernt-Erik; Ringsby, Thor Harald (Journal article, 2013)When investigating parasite–host dynamics in wild populations, a fundamental parameter to investigate is prevalence. This quantifies the percentage of individuals infected in the population. Investigating how prevalence ... -
The parasite Syngamus trachea in a metapopulation of house sparrows
Holand, Håkon (Doktoravhandlinger ved NTNU, 1503-8181; 2014:178, Doctoral thesis, 2014)Understanding the effects of parasites on population dynamics of hosts is an important, and often neglected, part of population ecology. In this thesis I first investigate the spatio-temporal distribution of the parasite ...