Research Topics
 S EngenSummaryAffiliation: Norwegian University of Science and Technology Country: Norway Publications
 Collaborators

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Publications
 Heterogeneous communities with lognormal species abundance distribution: Speciesarea curves and sustainabilitySteinar Engen
Department of Mathematical Sciences, Norwegian University for Science and Technology, N 7491 Trondheim, Norway
J Theor Biol 249:791803. 2007..The method is exemplified by analyzing three simulated data sets...  A quantitative genetic model of r and Kselection in a fluctuating populationSteinar Engen
Center for Biodiversity Dynamics, Department of Mathematical Sciences, Norwegian University of Science and Technology, N 7491 Trondheim, Norway
Am Nat 181:72536. 2013..For the thetalogistic model of density dependence, evolution tends to maximize the expected value of N(θ)...  Evolution of a plastic quantitative trait in an agestructured population in a fluctuating environmentSteinar Engen
Centre for Conservation Biology, Department of Mathematical Sciences, Norwegian University of Science and Technology, NO 7491 Trondheim, Norway
Evolution 65:2893906. 2011..The "agespecific selective weights" are related to the stable distribution of reproductive values among age classes. This allows partitioning of the change in the weighted mean character into agespecific components...  A general model for analyzing Taylor's spatial scaling lawsSteinar Engen
Centre for Conservation Biology, Department of Mathematical Sciences, Norwegian University for Science and Technology, N 7491 Trondheim, Norway
Ecology 89:261222. 2008..We also show how properties of population dynamics in space and time determine this relationship...  Stochastic growth and extinction in a spatial geometric Brownian population model with migration and correlated noiseSteinar Engen
Department of Mathematical Sciences, Norwegian University of Science and Technology, N 7491 Trondheim, Norway
Math Biosci 209:24055. 2007..However, as the area occupied by the species starts to decrease, the decrease is faster for populations with larger migration...  Heterogeneity in dynamic species abundance models: the selective effect of extinction processesSteinar Engen
Department of Mathematical Sciences, Norwegian University for Science and Technology, N 7491, Trondheim, Norway
Math Biosci 210:490507. 2007....  Effective size of fluctuating populations with two sexes and overlapping generationsSteinar Engen
Population Biology Center, Department of Mathematical Sciences, Norwegian University of Science and Technology, N 7491 Trondheim, Norway
Evolution 61:187385. 2007..This ratio showed large interisland variation because of demographic differences among the populations. Finally, we calculate how N(e) in a growing house sparrow population will change over time...  Fixation probability of beneficial mutations in a fluctuating populationSteinar Engen
Centre for Conservation Biology, Department of Mathematical Sciences, Norwegian University of Science and Technology, N 7491 Trondheim, Norway
Genet Res (Camb) 91:7382. 2009..Effective population size based on harmonic mean population size will therefore underestimate the expected fixation rate of beneficial mutations in fluctuating populations...  Reproductive value and the stochastic demography of agestructured populationsSteinar Engen
Centre for Conservation Biology, Department of Mathematical Sciences, Norwegian University of Science and Technology, N 7491 Trondheim, Norway
Am Nat 174:795804. 2009..The estimates are based on yearly random samples of individual vital rates and require no information about the total population size...  Estimating the ratio of effective to actual size of an agestructured population from individual demographic dataSteinar Engen
Department of Mathematical Sciences, Centre for Conservation Biology, Norwegian University of Science and Technology, Trondheim, Norway
J Evol Biol 23:114858. 2010..We also show how to incorporate uncertain paternity...  Using reproductive value to estimate key parameters in densityindependent agestructured populationsSteinar Engen
Department of Mathematical Sciences, Norwegian University of Science and Technology, N 7491 Trondheim, Norway
J Theor Biol 244:30817. 2007..We illustrate the method by estimating the longrun growth rate and the environmental variance in an exponentially growing population of Bighorn Sheep...  Generalizations of the Moran effect explaining spatial synchrony in population fluctuationsSteinar Engen
Department of Mathematical Sciences, Norwegian University for Science and Technology, N 7491, Trondheim, Norway
Am Nat 166:60312. 2005..These analyses show exactly how spatial environmental covariation can synchronize fluctuations of spatially segregated populations with no interchange of individuals even if the dynamics are nonlinear...  A dynamic and spatial model with migration generating the logGaussian field of population densitiesS Engen
Institute for Mathematical Sciences, Norwegian University of Science and Technology, Gløshaugen, N 7491 Trondheim, Norway
Math Biosci 173:85102. 2001..The model is generalized to describe communities of species leading to a dynamic and spatial lognormal species abundance model with migration...  Extinction in relation to demographic and environmental stochasticity in agestructured modelsSteinar Engen
Institute for Mathematical Sciences, Norwegian University for Science and Technology, N 7491 Trondheim, Norway
Math Biosci 195:21027. 2005..We also compute estimates of the agespecific contributions to the total demographic variance from survival, fecundity and the covariance between survival and fecundity...  Reproductive value and fluctuating selection in an agestructured populationSteinar Engen
Centre for Conservation Biology, Department of Mathematical Sciences, Norwegian University of Science and Technology, Trondheim, Norway
Genetics 183:62937. 2009..We develop statistical methods for measuring the expected selection on the reproductive value weighted allele frequency in a fluctuating agestructured population...  Effective size of a fluctuating agestructured populationSteinar Engen
Department of Mathematical Sciences, Norwegian University of Science and Technology, Trondheim
Genetics 170:94154. 2005..A formula for the effective population size over longer time intervals incorporates deterministic growth and environmental stochasticity to account for changes in N...  Geographical variation in the influence of density dependence and climate on the recruitment of Norwegian mooseVidar Grøtan
Department of Biology, Centre for Conservation Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
Oecologia 161:68595. 2009..These patterns demonstrate both direct and delayed effects of weather on the recruitment of moose that possibly operate through an effect of body mass on the proportion of the females that sexually mature as 1.5 or 2.5 years old...  Estimating fluctuating selection in agestructured populationsS Engen
Department of Mathematical Sciences, Centre for Conservation Biology, Norwegian University of Science and Technology, Trondheim, Norway
J Evol Biol 25:148799. 2012..The method is illustrated by an analysis of agespecific selection in house sparrows on a fitnessrelated twodimensional morphological trait, tarsus length and body mass of fledglings...  Population dynamical consequences of climate change for a small temperate songbirdB Saether
Department of Zoology, Norwegian University of Science and Technology, N 7491 Trondheim, Norway
Science 287:8546. 2000....  Inferring patterns of migration from gene frequencies under equilibrium conditionsJ Tufto
Norwegian Institute for Nature Research, Trondheim, Norway
Genetics 144:191121. 1996..Possible ecological extensions of the model are discussed...  Analysis of genetic structure and dispersal patterns in a population of sea beetJ Tufto
Norwegian Institute for Nature Research, 7005 Trondheim, Norway
Genetics 149:197585. 1998..Finally, we note that the data also appear to contain some information about this ratio...  Demographic characteristics and population dynamical patterns of solitary birdsBernt Erik Saether
Department of Zoology, Norwegian University of Science and Technology, N 7491 Trondheim, Norway
Science 295:20703. 2002..These results suggest that patterns in avian population fluctuations can be predicted from a knowledge of lifehistory characteristics and/or temporal variation in certain demographic traits...  Fixation of slightly beneficial mutations: effects of life historyYngvild Vindenes
Center for Conservation Biology, Department of Biology, Norwegian University of Science and Technology, N 7491 Trondheim, Norway
Evolution 64:106375. 2010..The demographic variance also determines what influence population size has on the fixation probability. This model represents a substantial generalization of earlier models, covering a large range of life histories...  Critical parameters for predicting population fluctuations of some British passerinesBernt Erik Saether
Centre for Conservation Biology, Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
J Anim Ecol 78:106375. 2009..7. These results show that constructing PPI by stochastic simulations may be a useful tool for obtaining reliable population projections...  Influence of soil acidification in southern Norway on the 137Cs exposure of moose?Eiliv Steinnes
Department of Chemistry, Norwegian University of Science and Technology, NO 7491 Trondheim, Norway
Sci Total Environ 407:39058. 2009....  Spatial and temporal variation in the relative contribution of density dependence, climate variation and migration to fluctuations in the size of great tit populationsVidar Grøtan
Department of Biology, Centre for Conservation Biology, Norwegian University of Science and Technology, Trondheim, Norway
J Anim Ecol 78:44759. 2009..This effect of environment on the interchange of individuals among populations is important for predicting effects of global climate change on the pattern of population fluctuations...  Climate and spatiotemporal variation in the population dynamics of a long distance migrant, the white storkBernt Erik Saether
Department of Biology, Norwegian University of Science and Technology, N 7491 Trondheim, Norway
J Anim Ecol 75:8090. 2006..6. Our results illustrate that evaluating the effects of common environmental variables on the spatiotemporal variation in population dynamics require estimates and modelling of their influence on the local dynamics...  The extended Moran effect and largescale synchronous fluctuations in the size of great tit and blue tit populationsBernt Erik Saether
Department of Biology, Norwegian University of Science and Technology, NO 7491 Trondheim, Norway
J Anim Ecol 76:31525. 2007....  Generation time and temporal scaling of bird population dynamicsBernt Erik Saether
Department of Biology, Norwegian University of Science and Technology, N 7491 Trondheim, Norway
Nature 436:99102. 2005..These results indicate that the relationships between demographic and lifehistory traits in birds translate into distinct population dynamical patterns that are apparent only on a scale of generations...  Demographic characteristics of extinction in a small, insular population of house sparrows in northern NorwayThor Harald Ringsby
Department of Biology, Norwegian University of Science and Technology, N 7491, Trondheim, Norway
Conserv Biol 20:17617. 2006..Our results strongly emphasize the importance of access to data on temporal variation that can be used to parameterize simple population models that allow estimation of critical parameters for credible prediction of time to extinction...  Predicting fluctuations of reintroduced ibex populations: the importance of density dependence, environmental stochasticity and uncertain population estimatesBernt Erik Saether
Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
J Anim Ecol 76:32636. 2007..Credible population predictions require that this uncertainty is properly quantified...  Climate variation and regional gradients in population dynamics of two holenesting passerinesBernt Erik Saether
Department of Biology, Norwegian University of Science and Technology, N 7491 Trondheim, Norway
Proc Biol Sci 270:2397404. 2003..In both species, the effects will be larger in those parts of Europe where large changes in climate are expected...  Pattern of variation in avian population growth ratesBernt Erik Saether
Department of Zoology, Norwegian University of Science and Technology, Realfagsbygget, N 7491 Trondheim, Norway
Philos Trans R Soc Lond B Biol Sci 357:118595. 2002..We illustrate that the concept of population prediction interval can be useful in evaluating the consequences of these uncertainties in the population projections for the choice of management actions...  Understanding mating systems: a mathematical model of the pair formation processAline Magdalena Lee
Centre for Conservation Biology, Department of Biology, Norwegian University of Science and Technology, Realfagsbygget, N 7491 Trondheim, Norway
Theor Popul Biol 73:11224. 2008..This emphasizes the importance of using a model of this type to study mating systems, rather than relying solely on the variance in reproductive success as a descriptor of different systems...  Estimation of population parameters from aerial counts of North American mallards: a cautionary taleMagnar Lillegård
Centre for Conservation Biology, Department of Mathematical Sciences, Norwegian University of Science and Technology, N 7491 Trondheim, Norway
Ecol Appl 18:197207. 2008..Our results underline the importance of reducing the magnitude of sampling error in the design of largescale monitoring programs of population fluctuations...  Geographical gradients in the population dynamics of North American prairie ducksBernt Erik Saether
Department of Biology, Centre for Conservation Biology, Norwegian University of Science and Technology, Trondheim, Norway
J Anim Ecol 77:86982. 2008..5. These results suggest that future management of these species could be improved by implementing harvest models that account explicitly for spatial variation in density effects and environmental stochasticity on population abundance...  Individual heterogeneity in vital parameters and demographic stochasticityYngvild Vindenes
Centre for Conservation Biology, Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
Am Nat 171:45567. 2008..Thus, we provide a general theoretical framework for analyzing how individual heterogeneity caused by different biological mechanisms affects fluctuations of especially small populations...  Rarity, life history and scaling of the dynamics in time and space of British birdsBernt Erik Saether
Centre for Conservation Biology, Department of Biology, Norwegian University of Science and Technology, NO 7491 Trondheim, Norway
J Anim Ecol 80:21524. 2011..g. due to human activities, key population dynamical characteristics will change because of densitydependent stochastic effects, which in turn are dependent on speciesspecific lifehistory characteristics...  Estimating the time to extinction in an island population of song sparrowsB E Saether
Department of Zoology, Norwegian University of Science and Technology, Trondheim
Proc Biol Sci 267:6216. 2000..This study shows that ignoring uncertainties in population dynamics produces a substantial underestimation of the extinction risk...  Effects of climate change and variability on population dynamics in a longlived shorebirdMartijn Van de Pol
Centre for Conservation Biology, Department of Biology, Norwegian University of Science and Technology NTNU, NO 7491 Trondheim, Norway
Ecology 91:1192204. 2010..Disturbingly, such data are unavailable for most species of conservation concern...  An efficient multivariate approach for estimating preference when individual observations are dependentSteinar Engen
Department of Mathematical Sciences, Centre for Conservation Biology, Norwegian University for Science and Technology, Trondheim, Norway
J Anim Ecol 77:95865. 2008..4. The method is demonstrated using a data set of radiotagged dispersing juvenile goshawks and their site characteristics, and can be used as a general tool in resource or habitat selection analysis...