scholarly journals Population dynamics and spatial structure of human-biting mosquitoes, inside and outside of houses, in the Chockwe irrigation scheme, southern Mozambique

2013 ◽  
Vol 7 (2) ◽  
pp. 309 ◽  
Author(s):  
J. Derek Charlwood ◽  
Gracieta A. Macia ◽  
Maria Manhaca ◽  
Bruno Sousa ◽  
Nelson Cuamba ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Spatial Structure ◽  
Irrigation Scheme

scholarly journals Population dynamics with spatial structure and an Allee effect

2020 ◽  
Author(s):  
Anudeep Surendran ◽  
Michael Plank ◽  
Matthew Simpson
Keyword(s):  
Population Dynamics ◽  
Spatial Structure ◽  
Short Range ◽  
Allee Effect ◽  
Mean Field ◽  
Mean Field Approximation ◽  
Continuum Approximation ◽  
Spatial Moment ◽  
Mean Field Models ◽  
The Mean

AbstractAllee effects describe populations in which long-term survival is only possible if the population density is above some threshold level. A simple mathematical model of an Allee effect is one where initial densities below the threshold lead to population extinction, whereas initial densities above the threshold eventually asymptote to some positive carrying capacity density. Mean field models of population dynamics neglect spatial structure that can arise through short-range interactions, such as short-range competition and dispersal. The influence of such non mean-field effects has not been studied in the presence of an Allee effect. To address this we develop an individual-based model (IBM) that incorporates both short-range interactions and an Allee effect. To explore the role of spatial structure we derive a mathematically tractable continuum approximation of the IBM in terms of the dynamics of spatial moments. In the limit of long-range interactions where the mean-field approximation holds, our modelling framework accurately recovers the mean-field Allee threshold. We show that the Allee threshold is sensitive to spatial structure that mean-field models neglect. For example, we show that there are cases where the mean-field model predicts extinction but the population actually survives and vice versa. Through simulations we show that our new spatial moment dynamics model accurately captures the modified Allee threshold in the presence of spatial structure.

scholarly journals Recession of Tussilago farfara (L.) population from the agro coenose as a result of cultivation abandonment. I The effect of fallowing on population dynamics

2014 ◽  
Vol 57 (3) ◽  
pp. 371-386
Author(s):  
Anna Namura-Ochalska
Keyword(s):  
Population Dynamics ◽  
Spatial Structure ◽  
Interspecific Competition ◽  
Population Size ◽  
Dactylis Glomerata ◽  
Tussilago Farfara ◽  
Agropyron Repens

The paper evaluates the effect of fallowing on seasonal and multiyear dynamics, as well as on the spatial structure of <em>Tussilago farfara</em> population. In four years turfing and rapid increase in the size of grass populations - those of <em>Agropyron repens</em> (L.) PB. and <em>Dactylis glomerata</em> caused the elimination of <em>Tussilago farfara</em> population. The studies have showed that a decrease in the population size resulted from hampering of both vegetative and generative reproduction. The interspecific competition for available space seems to be a crucial factor limiting emergence of new shoots. In the agrocoenose big population size of <em>Tussilago farfara</em> remained throughout the studies.

Stock assessment of school shark, Galeorhinus galeus, based on a spatially explicit population dynamics model

2000 ◽  
Vol 51 (3) ◽  
pp. 205 ◽  
Author(s):  
André E. Punt ◽  
Fred Pribac ◽  
Terence I. Walker ◽  
Bruce L. Taylor ◽  
Jeremy D. Prince
Keyword(s):  
Population Dynamics ◽  
Spatial Structure ◽  
Stock Assessment ◽  
Dynamics Model ◽  
Point Estimates ◽  
Population Dynamics Model ◽  
Equilibrium Size ◽  
Assessment Approach ◽  
The Status ◽  
Galeorhinus Galeus

The school shark (Galeorhinus galeus) resource off southern Australia is assessed by use of an assessment approach that takes account of the spatial structure of the population. The population dynamics model underlying the assessment considers the spatial as well as the age-specific characteristics of school shark. It allows for a series of fisheries (each based on a different gear type), explicitly models the pupping/recruitment process, and allows for multiple stocks. The values for the parameters of this model are determined by fitting it to catch-rate data and information from tagging studies. The point estimates of the pup production at the start of 1997 range from 12% to 18% of the pre-exploitation equilibrium size, depending on the specifications of the assessment. Allowing for spatial structure and incorporating tag release–recapture data lead to reduced uncertainty compared with earlier assessments. The status of the resource, as reflected by the ratio of present to virgin pup production and total (1+) biomass, is sensitive to the assumed level of movement between the stocks in New Zealand and those in Australia, with lower values corresponding to higher levels of movement.

scholarly journals Simulation modelling as a tool for examining the consequences of spatial structure and connectivity on local and regional population dynamics

2010 ◽  
Vol 67 (8) ◽  
pp. 1631-1639 ◽  
Author(s):  
Lisa A. Kerr ◽  
Steven X. Cadrin ◽  
Dave H. Secor
Keyword(s):  
Population Dynamics ◽  
Spatial Structure ◽  
Atlantic Cod ◽  
White Perch ◽  
Simulation Modelling ◽  
Model Framework ◽  
Environmental Forcing ◽  
High Productivity ◽  
Dynamics Of Population ◽  
Regional Population

Abstract Kerr, L. A., Cadrin, S. X., and Secor, D. H. 2010. Simulation modelling as a tool for examining the consequences of spatial structure and connectivity on local and regional population dynamics. – ICES Journal of Marine Science, 67: 1631–1639. An understanding of the mechanisms underlying population persistence makes fisheries management more effective. A model framework is described, which can test hypotheses about spatial structure and connectivity within and between populations and their influence on the productivity (spawning-stock biomass, SSB), stability (variation in SSB), resilience (time to rebuild SSB after environmental disturbance), and sustainability (maximum sustainable fishing mortality and yield) of systems. The general model consists of linked age-structured submodels that incorporate the unique demographics and dynamics of population components, along with the degree and type of connectivity between them. The flexibility of this framework is illustrated with three case studies examining (i) spatial structure within a population of white perch, (ii) different types and degrees of connectivity between populations of Atlantic herring, and (iii) spatial heterogeneity and connectivity within a stock of Atlantic cod. System variance is reduced by abundant, stable population components, and the asynchronous responses of those components. Components with high productivity contributed disproportionately to the resilience of systems. Increased synchrony of component responses to environmental forcing decreased the stability of the overall system. Simulation modelling is a useful approach to evaluate the consequences of spatial structure and connectivity, and can be used to understand better the productivity and dynamics of local and regional populations.

scholarly journals Small-scale spatial structure influences large-scale invasion rates

2019 ◽  
Author(s):  
Michael J. Plank ◽  
Matthew J. Simpson ◽  
Rachelle N. Binny
Keyword(s):  
Population Dynamics ◽  
Spatial Structure ◽  
Large Scale ◽  
Spatial Scales ◽  
Mean Field ◽  
Average Density ◽  
Small Scale ◽  
Local Interactions ◽  
Mean Field Model ◽  
Species Invasions

AbstractLocal interactions among individual members of a population can generate intricate small-scale spatial structure, which can strongly influence population dynamics. The two-way interplay between local interactions and population dynamics is well understood in the relatively simple case where the population occupies a fixed domain with a uniform average density. However, the situation where the average population density is spatially varying is less well understood. This situation includes ecologically important scenarios such as species invasions, range shifts, and moving population fronts. Here, we investigate the dynamics of the spatial stochastic logistic model in a scenario where an initially confined population subsequently invades new, previously unoccupied territory. This simple model combines density-independent proliferation with dispersal, and density-dependent mortality via competition with other members of the population. We show that, depending on the spatial scales of dispersal and competition, either a clustered or a regular spatial structure develops over time within the invading population. In the short-range dispersal case, the invasion speed is significantly lower than standard predictions of the mean-field model. We conclude that mean-field models, even when they account for non-local processes such as dispersal and competition, can give misleading predictions for the speed of a moving invasion front.

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