S Engen

..The method is exemplified by analyzing three simulated data sets...

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..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...

..We illustrate the method by estimating the long-run growth rate and the environmental variance in an exponentially growing population of Bighorn Sheep...

..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...

..We also show how properties of population dynamics in space and time determine this relationship...

..We also compute estimates of the age-specific contributions to the total demographic variance from survival, fecundity and the covariance between survival and fecundity...

..However, as the area occupied by the species starts to decrease, the decrease is faster for populations with larger migration...

..Effective population size based on harmonic mean population size will therefore underestimate the expected fixation rate of beneficial mutations in fluctuating populations...

..We develop statistical methods for measuring the expected selection on the reproductive value weighted allele frequency in a fluctuating age-structured population...

..The model is generalized to describe communities of species leading to a dynamic and spatial lognormal species abundance model with migration...

..The estimates are based on yearly random samples of individual vital rates and require no information about the total population size...

..We also show how to incorporate uncertain paternity...

..The "age-specific 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 age-specific components...

..A formula for the effective population size over longer time intervals incorporates deterministic growth and environmental stochasticity to account for changes in N...

..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...

..The method is illustrated by an analysis of age-specific selection in house sparrows on a fitness-related two-dimensional morphological trait, tarsus length and body mass of fledglings...

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..Possible ecological extensions of the model are discussed...

..Finally, we note that the data also appear to contain some information about this ratio...

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..7. These results show that constructing PPI by stochastic simulations may be a useful tool for obtaining reliable population projections...

..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...

..These results suggest that patterns in avian population fluctuations can be predicted from a knowledge of life-history characteristics and/or temporal variation in certain demographic traits...

..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...

..Thus, we provide a general theoretical framework for analyzing how individual heterogeneity caused by different biological mechanisms affects fluctuations of especially small populations...

..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...

..In both species, the effects will be larger in those parts of Europe where large changes in climate are expected...

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..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...

..6. Our results illustrate that evaluating the effects of common environmental variables on the spatio-temporal variation in population dynamics require estimates and modelling of their influence on the local dynamics...

..Credible population predictions require that this uncertainty is properly quantified...

..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...

..Our results underline the importance of reducing the magnitude of sampling error in the design of large-scale monitoring programs of population fluctuations...

..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...

..These results indicate that the relationships between demographic and life-history traits in birds translate into distinct population dynamical patterns that are apparent only on a scale of generations...

..g. due to human activities, key population dynamical characteristics will change because of density-dependent stochastic effects, which in turn are dependent on species-specific life-history characteristics...

..This study shows that ignoring uncertainties in population dynamics produces a substantial underestimation of the extinction risk...

..4. The method is demonstrated using a data set of radio-tagged dispersing juvenile goshawks and their site characteristics, and can be used as a general tool in resource or habitat selection analysis...

..Disturbingly, such data are unavailable for most species of conservation concern...