Dynamics of Populations with Density-Dependent Recruitment and Age Structure

1997 ◽  
pp. 371-408 ◽  
Author(s):  
Louis W. Botsford
Keyword(s):  
Age Structure ◽  
Density Dependent ◽  
Dynamics Of Populations

Seasonality in reproduction, age structure and density of the gracile mouse opossum Gracilinanus microtarsus (Marsupialia: Didelphidae) in a Brazilian cerrado

2006 ◽  
Vol 22 (4) ◽  
pp. 461-468 ◽  
Author(s):  
Eduardo Guimarães Martins ◽  
Vinícius Bonato ◽  
Cibele Queiroz da-Silva ◽  
Sérgio Furtado dos Reis
Keyword(s):  
Age Structure ◽  
Temporal Pattern ◽  
Food Limitation ◽  
Wet Season ◽  
Endogenous Factors ◽  
Eastern Brazil ◽  
Feedback Structure ◽  
Dynamics Of Populations ◽  
Long Term Studies

The temporal pattern of reproduction and its consequences for age structure and density were investigated in a population of the gracile mouse opossum Gracilinanus microtarsus in south-eastern Brazil. Individuals of G. microtarsus were monitored through capture–mark–recapture methods from August 2000 to February 2003 in a remnant of cerradão, a forest-like physiognomy of the highly seasonal cerrado biome. The temporal pattern of reproduction of the population studied was highly seasonal with rearing of the offspring occurring in the first half of the warm-wet season, when the abundance of food resources – primarily insects – in the cerrado is high. Shortly after reproduction, the density of adults decreased sharply, possibly because of high post-mating mortality, leading to a gradual replacement of adults by their offspring in the following months and little overlap of generations. Our data suggest that climatic and environmental factors affect the onset of reproduction and interact with endogenous factors that decrease post-mating survival to produce the observed pattern of seasonal variation in age structure and density. It is suggested that the dynamics of populations of G. microtarsus may be driven primarily by food limitation and that long-term studies are needed to understand its feedback structure.

Maximum sustainable yield with continuous age structure and density-dependent recruitment

1994 ◽  
Vol 120 (1) ◽  
pp. 99-126 ◽  
Author(s):  
Bernard Dacorogna ◽  
François Weissbaum ◽  
Roger Arditi
Keyword(s):  
Age Structure ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Density Dependent

Dynamics of populations with delayed density dependent birth rate regulation

2016 ◽  
Vol 340 ◽  
pp. 64-73 ◽  
Author(s):  
G.P. Neverova ◽  
I.P. Yarovenko ◽  
E.Ya. Frisman
Keyword(s):  
Birth Rate ◽  
Rate Regulation ◽  
Density Dependent ◽  
Dynamics Of Populations

Introduction to Population Models

2021 ◽  
pp. 25-46
Author(s):  
Timothy E. Essington
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Population Size ◽  
Population Models ◽  
Change Model ◽  
Density Dependent ◽  
Intrinsic Factors ◽  
Model Understanding ◽  
Dynamics Of Populations ◽  
Simple Models

The chapter “Introduction to Population Models” introduces unstructured population models and shows how model decisions can change model behavior, the different ways that feedbacks can be represented, and how one evaluates the consequences of those feedbacks. The goal here is to show how modeling a single entity, population density, can be done in many different ways, depending on the purpose of the model. Understanding the dynamics of populations remains one of the fundamental goals of ecology. Not surprisingly, many models have contributed to the theory of population dynamics and regulation. The models vary considerably in terms of depth, breadth, intended uses (e.g. prediction vs. generality), and structure. This chapter will largely focus on the behavior of simple models, to see how intrinsic factors can dictate variability in population size. Density-independent and density-dependent models are covered, as well as methods used to understand model behaviors.

The Founding Population - the Effect of Differences in Its Size, Nature and Season of Establishment on the Subsequent Dynamics of Populations of House Mice, Mus-Musculus L

1990 ◽  
Vol 38 (5) ◽  
pp. 479
Author(s):  
PR Pennycuik ◽  
AH Reisner
Keyword(s):  
Age Structure ◽  
Wide Band ◽  
Age Classes ◽  
South Eastern ◽  
Founding Population ◽  
Eastern Australia ◽  
Agricultural Areas ◽  
Ephemeral Habitats ◽  
Dynamics Of Populations ◽  
South Eastern Australia

In south-eastern Australia, house mouse numbers in agricultural areas often reach plague proportions in the year following the breaking of a drought but numbers are usually low in subsequent years. The effects of differences in the size and nature of the groups invading ephemeral habitats on sub- sequent numbers, and on the time taken for the population to peak, were investigated by introducing groups of different size, age structure and composition into out-door pens where food supplies were abundant. The effects of differences in the season of invasion and the effects of allowing mice from one or two sources to invade empty home sites were also investigated. Varying the size of the founding groups had little effect on peak numbers or on the length of the establishment-peak interval. Peak numbers were usually higher in populations established with mice from a narrow band of age classes than in those established with mice from a wide band of age classes, and the establishment-peak interval was usually shorter in populations established with mice from one source than in populations established with mice from two sources. The establishment-peak interval was also shorter in populations established in spring than in those established at other seasons. When established groups were allowed access to empty home sites, the groups colonising the sites varied in size, age structure and composition. Peak heights in these colonies, too, appeared to be affected by the age structure of the founding group, and the establishment-peak interval was affected by the composition of the group. These results suggest that both between-year differences in the nature of the groups moving from the refuge areas to the growing crops, and between-year differences in the season at which the crops are colonised, could contribute to the observed differences in mouse numbers in the agricultural areas of south-eastern Australia. Possible reasons for between-year differences in the nature of the groups colonising the ephemeral habitats are discussed.

Population Dynamics of Spiny Dogfish (Squalus acanthias) in British Columbia Waters

1979 ◽  
Vol 36 (6) ◽  
pp. 647-656 ◽  
Author(s):  
C. C. Wood ◽  
K. S. Ketchen ◽  
R. J. Beamish
Keyword(s):  
British Columbia ◽  
Population Dynamics ◽  
Age Structure ◽  
Squalus Acanthias ◽  
Minimum Size ◽  
Spiny Dogfish ◽  
Natural Mortality ◽  
Structure Model ◽  
Density Dependent ◽  
Sustained Effort

An age-structure model that incorporates recent information regarding growth and reproduction has been developed to investigate the dynamics of spiny dogfish (Squalus acanthias) populations in British Columbia waters. Mechanisms for density-dependent regulation of abundance were evaluated on the basis of theoretical effectiveness and ability to predict observed patterns in simulations of the historical fishery. Compensatory change in the rate of natural mortality appears to be the principal mechanism for density-dependent response. The instantaneous rate of natural mortality at natural equilibrium was estimated to be 0.094 MSY for British Columbia waters is ~ 9000–11 000 t/yr. The minimum size at entry to the fishery has little effect on MSY. Sustained-effort, sustained-yield, and periodic fisheries were modeled to determine optimum harvesting strategies. Periodic fisheries were found to vary widely in feasibility and appear to be impractical from a management perspective whereas a sustained-effort fishery would ensure maximum stability. Key words: spiny dogfish, population dynamics, age-structure model, density-dependence, simulation model, commercial fishing strategies

Effect of Individual Growth Rates on Expected Behavior of the Northern California Dungeness Crab (Cancer magister) Fishery

1984 ◽  
Vol 41 (1) ◽  
pp. 99-107 ◽  
Author(s):  
Louis W. Botsford
Keyword(s):  
Age Structure ◽  
Growth Pattern ◽  
Specific Model ◽  
Individual Growth ◽  
Time Lags ◽  
Northern California ◽  
Dungeness Crab ◽  
Cancer Magister ◽  
Density Dependent ◽  
The Mean

Cycles in the northern California Dungeness crab (Cancer magister) fishery may be caused by density-dependent recruitment or a cyclic environmental variable. Investigation of these potential causes requires knowledge of the age(s) at which crabs enter the fishery. Behavior of this fishery has previously been analyzed using mathematical models that include density-dependent recruitment and describe changes in age structure with time. From data available on the northern California crab population and a review of previous studies elsewhere it appears that a single year-class of crabs enters this fishery over several years rather than in one year as described by models with only age structure. The realism of models of this fishery can therefore be increased by including size structure. Behavior of size-specific models is in general different from that of age-specific models. However, it is shown here that an effective survival rate can be derived from a size-specific model that enables interpretation as an age-specific model. This is used to demonstrate that inclusion of size dispersion in a population model increases stability, but if the mean age of the population is not changed, it will not substantially change the period of cycles. Because the growth pattern developed here changes the mean age of entry into the fishery it results in cycles with a longer period than determined in previous analyses. With regard to environmental causes, this growth pattern implies time lags of 4 and 5 yr between an environmental factor affecting recruitment and its effect on the catch record.

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