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."

scholarly journals Estimation of the Number of Cumulative COVID-19 Cases by Day in Thailand Based on a Flattened Curve Policy

2021 ◽  
Vol 18 (13) ◽  
Author(s):  
Yupaporn AREEPONG ◽  
Rapin SUNTHORNWAT
Keyword(s):  
Growth Curve ◽  
Exponential Growth ◽  
Herd Immunity ◽  
Growth Curves ◽  
Least Square Method ◽  
Least Square ◽  
Coefficient Of Determination ◽  
Percentage Error ◽  
Logistic Growth ◽  
Thai Government

Since December 2019, the world has been facing an emerging infectious disease named coronavirus disease 2019. Thailand has also been affected by the spread of the coronavirus. The Thai government have announced policies to protect people, based on the emergency decree and curfew law for flattening the curve of the number of the coronavirus disease 2019 cases without vaccination in Thailand. This research estimated of the number of total infectious cases of coronavirus disease 2019 in Thailand. Two growth curves, including an exponential growth curve under a non-flattened curve policy (herd immunity policy without vaccination), and a logistic growth curve under a flattened curve policy without vaccination, were selected to estimate the parameters of the curves by the least square method to represent the number of the total infectious cases in Thailand. Moreover, the maximum infectious cases of coronavirus disease 2019 and the speed of spreading for coronavirus disease 2019 in Thailand were also explored. Based on the number of the total infectious cases of coronavirus disease 2019 in Thailand, the findings demonstrated that the coefficient of determination of the logistic growth curve was greater than the exponential growth curve and the root means squared percentage error of the logistic growth curve was less than the exponential growth curve. These results suggest that the logistic growth curve is suitable for describing the number of total infectious cases of coronavirus disease 2019 in Thailand under the fattened curve policy. GRAPHICAL ABSTRACT

Applications of Difference Equation in Population Forecasting Model

2014 ◽  
Vol 1079-1080 ◽  
pp. 664-667
Author(s):  
Chun Miao Huang ◽  
Wei Ping Wang
Keyword(s):  
Survival Rate ◽  
Difference Equation ◽  
Population Size ◽  
Urban Area ◽  
Rural Area ◽  
Total Population ◽  
Equation Model ◽  
Forecasting Model ◽  
Short Term ◽  
Population Forecasting

This article gets thepopulation data based on China Population Statistics Yearbook ,and establishes a model for forecasting thegrowth of population grouped by ages. First, a difference equation model invector form is established for urban area, town and rural arearespectively. In equation (I), matrix is determined byfertility rate and survival rate of urban area, townand rural area respectively. The short-term population size predicted from thismodel has calculated the gross population of each year during 2002~2020. The 19data we got were used to generate a function between population size y (hundredmillion) and time x (year) by polynomial fitting : , and the max of this function is y = 1.47121 billion when x= 20, which means that the Chinese total population will peak at 1, 471, 210,000 in 2021.

scholarly journals Mixed-effects growth curves in the valuation of Nellore sires

2009 ◽  
Vol 66 (1) ◽  
pp. 84-89
Author(s):  
Suely Ruiz Giolo ◽  
Robin Henderson ◽  
Clarice Garcia Borges Demétrio
Keyword(s):  
Random Effects ◽  
Growth Curve ◽  
Production Systems ◽  
Growth Curves ◽  
Logistic Growth ◽  
Cattle Breeding ◽  
Growth Curve Models ◽  
Fixed And Random Effects ◽  
Curve Model ◽  
Breeding Programmes

Cattle breeding programmes need objective criteria in order to evaluate and subsequently improve production systems. This work uses a logistic growth curve model for evaluating sires based on their progeny weight measured repeatedly over time. The parameters of the curve are described as a linear function of fixed and random effects. A Bayesian approach is used for the estimation. Analysis of the weights recorded on animals of the Nellore breed shows that growth curve models with fixed and random effects can be useful to evaluate and selecting sires.

scholarly journals HERBICIDE RESISTANT WEED MANAGEMENT USING SENSITIVITY ANALYSIS OF THE WEED POPULATION GROWTH CURVE

2010 ◽  
Vol 20 ◽  
Author(s):  
RIBAS ANTÔNIO VIDAL ◽  
FABIANE PINTO LAMEGO ◽  
MICHELÂNGELO MUZELL TREZZI ◽  
RAFAEL DE PRADO ◽  
NILDA ROMA BURGOS
Keyword(s):  
Sensitivity Analysis ◽  
Population Growth ◽  
Growth Curve ◽  
Weed Management ◽  
Logistic Growth ◽  
Control Methods ◽  
Herbicide Resistant ◽  
Weed Population ◽  
The Past ◽  
Weed Resistance

Strategies to prevent herbicide weed resistance are rarely practiced by farmers. As a consequence, herbicide resistant weed biotypes (HRWB) have been increasing worldwide in the past decades. This paper aims to analyze the weed population growth curve and to propose a strategic plan for prevention and management of HRWB. The existing weed control methods are organized considering the sensitivity analysis of the population growth at each phase of the logistic growth curve. This analysis indicates that tactics directed to reduce the population growth rate are most appropriate for HRWB management, mainly at the initial phase of the resistant weed population growth. This epidemiological approach provides evidence to the importance of early detection and management of HRWB.

scholarly journals Chaoslike states can be expected before and after logistic growth

2022 ◽  
Author(s):  
THEODORE MODIS
Keyword(s):  
Population Growth ◽  
Growth Curve ◽  
Logistic Growth ◽  
Filling Process ◽  
Discrete Form ◽  
Initial Rise ◽  
Before And After ◽  
Early Phases

Instabilities associated with population growth can be simulated by putting the logistic growth curve in a discrete form. In contrast to the usual derivation of chaos, which can only explain instabilities at the top of the curve, this method can also account for fluctuations during the early phases of the niche-filling process. Precursors, a steep initial rise, and final instabilities can all be interrelated. Industrial examples are given of logistic growth alternating with periods of chaotic fluctuations.

Interactions between population growth and sexual reproduction in the viviparous monogenean Gyrodactylus turnbulli Harris, 1986 from the guppy, Poecilia reticulata Peters

Parasitology ◽  
1989 ◽  
Vol 98 (2) ◽  
pp. 245-251 ◽  
Author(s):  
P.D. Harris
Keyword(s):  
Population Growth ◽  
Sexual Reproduction ◽  
Population Size ◽  
Asexual Reproduction ◽  
Population Biology ◽  
Poecilia Reticulata ◽  
Seminal Receptacle ◽  
Potential Importance ◽  
Sexual And Asexual Reproduction ◽  
First Time

SUMMARYMating was observed in populations of Gyrodactylus turnbulli from guppies. Copulation took place between older (post-1st birth) flukes and resulted in the insemination of spermatozoa into the seminal receptacle. New-born flukes, and flukes which had only recently given birth for the first time (in which the penis was absent or developing), were never inseminated. Flukes were promiscuous, copulating with several partners in succession. The occurrence of mating was related to the size, age and crowding of the G. turnbulli population, taking place most frequently when the parasites were most densely crowded upon the peduncle of the fish on days 5 and 6 of the infection. Maximum population size was positively correlated with the number of flukes initiating an infection. As a result, mating began earlier, and continued for longer in populations founded by several parasites rather than those begun by single flukes. These observations are discussed with respect to the population biology of G. turnbulli: it is likely that sexual and asexual reproduction alternate, with sex being important only during phases of epidemic population growth. The significance of sex in gyrodactylids is discussed, and the potential importance of continuous sexual reproduction in G. turnbulli infections on cultivated guppies is noted.

A method for the analysis of piosphere data applicable to range assessment.

1978 ◽  
Vol 1 (2) ◽  
pp. 126 ◽  
Author(s):  
RD Graetz ◽  
JA Ludwig
Keyword(s):  
Growth Curve ◽  
Population Biology ◽  
Assessment Method ◽  
Logistic Growth ◽  
Curve Equation ◽  
Potential Use

The logistic growth curve equation of population biology is shown to satisfactorily describe the responses of some vegetation and soil measures as a function of distance out from a watering point. Two of the three parameters of this equation can be readily related to parameters of the herbivore - rangeland ecosystem. The potential use of this equation is explored for the development of a simple, quantitative range assessment method. -

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