Beverton–Holt Model
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The Beverton–Holt model is a classic
discrete-time In mathematical dynamics, discrete time and continuous time are two alternative frameworks within which variables that evolve over time are modeled. Discrete time Discrete time views values of variables as occurring at distinct, separate "po ...
population model A population model is a type of mathematical model that is applied to the study of population dynamics. Rationale Models allow a better understanding of how complex interactions and processes work. Modeling of dynamic interactions in nature can ...
which gives the expected number ''n'' ''t''+1 (or
density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...
) of individuals in generation ''t'' + 1 as a function of the number of individuals in the previous generation, : n_ = \frac. Here ''R''0 is interpreted as the proliferation rate per generation and ''K'' = (''R''0 − 1) ''M'' is the
carrying capacity The carrying capacity of an environment is the maximum population size of a biological species that can be sustained by that specific environment, given the food, habitat, water, and other resources available. The carrying capacity is defined as t ...
of the environment. The Beverton–Holt model was introduced in the context of
fisheries Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life; or more commonly, the site where such enterprise takes place ( a.k.a. fishing ground). Commercial fisheries include wild fisheries and fish farms, both ...
by Beverton &
Holt Holt or holte may refer to: Natural world *Holt (den), an otter den * Holt, an area of woodland Places Australia * Holt, Australian Capital Territory * Division of Holt, an electoral district in the Australian House of Representatives in Vic ...
(1957). Subsequent work has derived the model under other assumptions such as contest competition (Brännström & Sumpter 2005), within-year resource limited competition (Geritz & Kisdi 2004) or even as the outcome of a source-sink Malthusian patches linked by density-dependent dispersal (Bravo de la Parra et al. 2013). The Beverton–Holt model can be generalized to include
scramble competition In ecology, scramble competition (or complete symmetric competition or exploitation competition) refers to a situation in which a resource is accessible to all competitors (that is, it is not monopolizable by an individual or group). However, sin ...
(see the
Ricker model The Ricker model, named after Bill Ricker, is a classic discrete population model which gives the expected number ''N'' ''t''+1 (or density) of individuals in generation ''t'' + 1 as a function of the number of individuals in the pre ...
, the Hassell model and the
Maynard Smith John Maynard Smith (6 January 1920 – 19 April 2004) was a British theoretical and mathematical evolutionary biologist and geneticist. Originally an aeronautical engineer during the Second World War, he took a second degree in genetics und ...
–Slatkin model). It is also possible to include a parameter reflecting the spatial clustering of individuals (see Brännström & Sumpter 2005). Despite being
nonlinear In mathematics and science, a nonlinear system is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, biologists, physicists, mathematicians, and many other ...
, the model can be solved explicitly, since it is in fact an inhomogeneous linear equation in 1/''n''. The solution is : n_t = \frac. Because of this structure, the model can be considered as the discrete-time analogue of the continuous-time
logistic equation A logistic function or logistic curve is a common S-shaped curve (sigmoid curve) with equation f(x) = \frac, where For values of x in the domain of real numbers from -\infty to +\infty, the S-curve shown on the right is obtained, with the ...
for
population growth Population growth is the increase in the number of people in a population or dispersed group. Actual global human population growth amounts to around 83 million annually, or 1.1% per year. The global population has grown from 1 billion in 1800 to ...
introduced by Verhulst; for comparison, the logistic equation is : \frac = rN \left( 1 - \frac \right), and its solution is : N(t) = \frac.


References

* * * * * {{DEFAULTSORT:Beverton-Holt model Demography Biostatistics Fisheries science Stochastic models