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 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. Mathematicall ...
) of individuals in generation ''t'' + 1 as a function of the number of individuals in the previous generation,
:
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 by
Beverton &
Holt (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, sinc ...
(see the
Ricker model, 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
:
Because of this structure, the model can be considered as the discrete-time analogue of the continuous-time
logistic equation 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
:
and its solution is
:
References
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{{DEFAULTSORT:Beverton-Holt model
Demography
Biostatistics
Fisheries science
Stochastic models