Dynamics of Populations. I. Factors Controlling Population Growth and Population Size in Drosophila serrata

1966 ◽  
Vol 100 (913) ◽  
pp. 333-344 ◽  
Author(s):  
Francisco J. Ayala
Keyword(s):  
Population Growth ◽  
Population Size ◽  
Drosophila Serrata ◽  
Dynamics Of Populations

scholarly journals Ethnic Immigration Policy Implementation (1992- 2009)

2013 ◽  
pp. 109-117
Author(s):  
Shugatai Amangul
Keyword(s):  
National Identity ◽  
Population Growth ◽  
Policy Implementation ◽  
Population Size ◽  
International Migration ◽  
Immigration Policy ◽  
International Affairs ◽  
Migration Process ◽  
Economic Stability ◽  
Positive Effect

After Kazakhstan declared its independence, it became a large perform­er in the worldwide international migration process. The attraction of social and economic stability (with an increase in the level of liv­ing standard), stable ethno-demographic and population growth, no nationalist struggles as well as positive geopolitical situations, have lead to a huge flow of immigrants to Kazakhstan in the years since independence. In this study, I have suggested that results of the ethnic immigration policy include strengthening the national identity, creating a positive effect on the ethno-demographic outcomes, and increasing the number of the population size over the last nineteen years. DOI: http://dx.doi.org/10.5564/mjia.v0i17.87 Mongolian Journal of International Affairs, No.17 2012: 109-117

scholarly journals Shifts in interregional proportions in population settlement over the territory of Russia in 2002-2017

2019 ◽  
Vol 3 (1) ◽  
pp. 21-37
Author(s):  
Pavel Kirillov ◽  
Alla Makhrova
Keyword(s):  
Population Growth ◽  
Population Size ◽  
Russian Federation ◽  
Turning Point ◽  
Medium Term ◽  
Local Growth ◽  
Population Redistribution ◽  
Migratory Movement ◽  
Federal Districts ◽  
The Russian Federation

Abstract The article deals with the trends of population size changes in the regions of the Russian Federation between 2002 and 2017 on the basis of data of all-Russian population censuses and current statistics. Components of population growth (natural and migratory movement of the population) are analyzed. In order to take into account the current situation of population size changes in the regions, which are largely of a “turning point” nature and partly inconsistent with the medium-term dynamics since the 2002 Census, the analysis is focused on the period from 2014 to 2017. The paper presents estimates of population size shifts at regional and macro-regional levels, identifies general and local growth centers and depopulation zones. Conclusions are drawn about general shifts in the proportions of population settlement over the territory of Russia and in certain macro-regions (federal districts). General conclusions about the trends of population redistribution across the territory of the country are given in the final part of the study.

The Wright–Fisher model with varying selection

1986 ◽  
Vol 23 (02) ◽  
pp. 504-508
Author(s):  
N. C. Weber
Keyword(s):  
Population Growth ◽  
Population Size ◽  
Sufficient Conditions ◽  
Selective Advantage ◽  
Fisher Model ◽  
Ultimate Homozygosity ◽  
Varying Population

The Wright–Fisher model with varying population size is examined in the case where the selective advantage varies from generation to generation. Models are considered where the selective advantage is not always in favour of a particular genotype. Sufficient conditions in terms of the selection coefficients and the population growth are given to ensure ultimate homozygosity.

Bionomics of Dytiscus alaskanus J. Balfour-Browne (Coleoptera: Dytiscidae) in a central Alberta lake

1985 ◽  
Vol 63 (6) ◽  
pp. 1316-1323 ◽  
Author(s):  
R. B. Aiken ◽  
C. W. Wilkinson
Keyword(s):  
Life History ◽  
Life Cycle ◽  
North America ◽  
Population Growth ◽  
Population Size ◽  
Total Population ◽  
Eutrophic Lake ◽  
North Central ◽  
Total Population Size

There are few studies of life history and population growth of large dytiscid beetles in North America. We sampled populations of Dytiscus alaskanus in a eutrophic lake in north central Alberta weekly in the summers of 1982 and 1983. Like many other temperate zone dytiscids, D. alaskanus has a univoltine life cycle. Dytiscus alaskanus prefers the area at the limit of emergent vegetation in the lake and is most often associated with shoreline vegetation of cattail and sedge. Populations of adult D. alaskanus are at a peak in the late spring and decline throughout the summer. Mark–recapture experiments allowed determination of total population size and monitoring of movement patterns in the lake. Data are discussed with reference to the relatively short summer with which these beetles must cope.

scholarly journals Could current fertility control methods be effective for landscape-scale management of populations of wild horses (Equus caballus) in Australia?

2018 ◽  
Vol 45 (3) ◽  
pp. 195 ◽  
Author(s):  
Rebecca J. Hobbs ◽  
Lyn A. Hinds
Keyword(s):  
Population Growth ◽  
Population Size ◽  
National Parks ◽  
Fertility Control ◽  
Management Approach ◽  
Attractive Alternative ◽  
Control Methods ◽  
Animal Populations ◽  
Rate Of Increase

Context Fertility control is seen as an attractive alternative to lethal methods for control of population size and genetic diversity in managed animal populations. Immunocontraceptive vaccines have emerged as the most promising agents for inducing long-term infertility in individual animals. However, after over 20 years of scientific testing of immunocontraceptive vaccines in the horse, the scientific consensus is that their application as a sole management approach for reducing population size is not an effective strategy. Aims The purpose of this review is to evaluate currently available non-lethal fertility-control methods that have been tested for their contraceptive efficacy in Equidae, and to assess their suitability for effective management of wild (feral) horses in an Australian setting. Key results (1) Fertility-control agents, particularly injectable immunocontraceptive vaccines based on porcine zona pellucida (PZP) or gonadotrophin-releasing hormone (GnRH), can induce multi-year infertility (up to 3 years) in the horse. Some formulations require annual or biennial booster treatments. Remote dart delivery (on foot) to horses is possible, although the efficacy of this approach when applied to large numbers of animals is yet to be determined. (2) The proportion of females that must be treated with a fertility-control agent, as well as the frequency of treatment required to achieve defined management outcomes (i.e. halting population growth in the short term and reducing population size in the long term) is likely to be >50% per annum. In national parks, treatment of a large number of wild horses over such a broad area would be challenging and impractical. (3) Fertility control for wild horses could be beneficial, but only if employed in conjunction with other broad-scale population-control practices to achieve population reduction and to minimise environmental impacts. Conclusions In Australia, most populations of wild horses are large, dispersed over varied and difficult-to-access terrain, are timid to approach and open to immigration and introductions. These factors make accessing and effectively managing animals logistically difficult. If application of fertility control could be achieved in more than 50% of the females, it could be used to slow the rate of increase in a population to zero (2–5 years), but it will take more than 10–20 years before population size will begin to decline without further intervention. Thus, use of fertility control as the sole technique for halting population growth is not feasible in Australia.

An optimal hunting policy for a stochastic logistic model

1979 ◽  
Vol 16 (2) ◽  
pp. 319-331 ◽  
Author(s):  
Andris Abakuks
Keyword(s):  
Population Growth ◽  
Population Size ◽  
Optimal Policy ◽  
Logistic Model ◽  
Stochastic Version ◽  
Stochastic Logistic Model ◽  
Parameter Values

A stochastic version of the logistic model for population growth is considered, and the general form of an optimal policy is found for hunting the population so as to maximise the long-term average number of captures per unit time. This optimal policy is described by a critical population size x∗such that it is optimal to hunt if and only if the population size is greater than or equal to x∗. Methods of determining x∗for given parameter values are provided, and some properties of the optimal policy as the population size tends to infinity are proved.

scholarly journals Evolution of stochastic demography with life history tradeoffs in density-dependent age-structured populations

2017 ◽  
Vol 114 (44) ◽  
pp. 11582-11590 ◽  
Author(s):  
Russell Lande ◽  
Steinar Engen ◽  
Bernt-Erik Sæther
Keyword(s):  
Life History ◽  
Population Growth ◽  
Density Dependence ◽  
Population Size ◽  
Structured Populations ◽  
Environmental Stochasticity ◽  
Trade Off ◽  
Density Dependent ◽  
Fluctuating Environment ◽  
Stochastic Demography

We analyze the stochastic demography and evolution of a density-dependent age- (or stage-) structured population in a fluctuating environment. A positive linear combination of age classes (e.g., weighted by body mass) is assumed to act as the single variable of population size, N, exerting density dependence on age-specific vital rates through an increasing function of population size. The environment fluctuates in a stationary distribution with no autocorrelation. We show by analysis and simulation of age structure, under assumptions often met by vertebrate populations, that the stochastic dynamics of population size can be accurately approximated by a univariate model governed by three key demographic parameters: the intrinsic rate of increase and carrying capacity in the average environment, r0 and K, and the environmental variance in population growth rate, σe2. Allowing these parameters to be genetically variable and to evolve, but assuming that a fourth parameter, θ, measuring the nonlinearity of density dependence, remains constant, the expected evolution maximizes E[Nθ]=[1−σe2/(2r0)]Kθ. This shows that the magnitude of environmental stochasticity governs the classical trade-off between selection for higher r0 versus higher K. However, selection also acts to decrease σe2, so the simple life-history trade-off between r- and K-selection may be obscured by additional trade-offs between them and σe2. Under the classical logistic model of population growth with linear density dependence (θ=1), life-history evolution in a fluctuating environment tends to maximize the average population size.

scholarly journals Noise-Induced Transitions in a Population Growth Model Based on Size-Dependent Carrying Capacity

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Neeme Lumi ◽  
Ain Ainsaar ◽  
Romi Mankin
Keyword(s):  
Population Growth ◽  
Population Size ◽  
Growth Model ◽  
Carrying Capacity ◽  
Stochastic Dynamics ◽  
Exact Analytical Solution ◽  
Probability Distributions ◽  
Stationary Probability Distribution ◽  
Size Dependent ◽  
Stochastic Case

The stochastic dynamics of a population growth model with size-dependent carrying capacity is considered. The effect of a fluctuating environment on population growth is modeled as a multiplicative dichotomous noise. At intermediate values of population size the deterministic counterpart of the model behaves similarly to the Von Foerster model for human population, but at small and very large values of population size substantial differences occur. In the stochastic case, an exact analytical solution for the stationary probability distribution is found. It is established that variation of noise correlation time can cause noise-induced transitions between three different states of the system characterized by qualitatively different behaviors of the probability distributions of the population size. Also, it is shown that, in some regions of the system parameters, variation of the amplitude of environmental fluctuations can induce single unidirectional abrupt transitions of the mean population size.

Relationship Between Two Stock–Recruitment Curves

1977 ◽  
Vol 34 (3) ◽  
pp. 425-428 ◽  
Author(s):  
L. L. Eberhardt
Keyword(s):  
Difference Equation ◽  
Population Growth ◽  
Population Size ◽  
Growth Curve ◽  
Population Biology ◽  
Population Regulation ◽  
Growth Curves ◽  
Equation Model ◽  
Logistic Growth ◽  
Stock Recruitment

The Beverton and Holt and Ricker stock–recruitment curves can be used to generate population growth curves. The Beverton and Holt curve is then identical to a difference equation model for the logistic growth curve, and may be derived in terms of equations for linearly density-dependent population regulation. The same equations lead to the Ricker curve if the density-regulating effect is assumed to depend only on population size at the beginning of the interval between generations. At low rates of population growth, the Ricker curve approaches that of Beverton and Holt. The two curves appear to represent certain concepts known in population biology as "r and K selection."

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