Biology Reference
In-Depth Information
theory of ecology. Their approach does not rely on equilibrium assump-
tions, and can be expected to become increasingly important in the
future.
A radically new approach for solving scientific problems in many fields
is that pioneered by Stephen Wolfram (Wolfram
2002
), i.e., NKS (''New
Kind of Science''). Wolfram applied NKS to evolution (see pp. 11-13).
The applicability of NKS to interpreting ecological processes is shown
by the following examples, which include the possibility of establishing
general ecological ''laws,'' the existence of vacant niches, the significance
of interspecific competition, and the causes of latitudinal gradients in
species diversity. All of these points are relevant to the discussion of equilib-
rium and nonequilibrium in ecological systems (see also Rohde 2005a).
Lawton (
1999
) raised the question of whether general laws are possible
in ecology and concluded that there are numerous ''laws'' in ecology in
the sense of widespread, repeatable patterns. However, there are ''hardly
any laws that are universally true'', because patterns depend on the
organisms involved and their environment. Even at the level of popula-
tions, it is highly unlikely that theory will ever become truly predictive.
At the level of communities, there are ''painfully few generalisations, let
alone rules or laws''. Wolfram's Principle of Computational Equivalence
provides the theoretical foundation for Lawton's conclusions. As
pointed out above, according to the principle, the computations necessary
to predict the fate of any complex system require at least as many steps as
contained in the system itself: in other words, general predictive laws
that permit shortcutting the computational process are impossible in
complex ecological systems. This conclusion is not contradicted by the
fact that predictions close to predictive ''laws'' can be made for those
characteristics of species and ecological systems that can be explained by
first principles of physics, chemistry, and physiology, as recently shown
by Gillooly et al.(
2002
), Allen et al.(
2002
), and Brown et al.(
2004
)
(see above and pp. 11, 161-164). Such a ''metabolic theory of ecology,''
based on temperature and mass dependence of metabolic rates, has, for
example, established quantitative relationships between temperature/
mass dependence of developmental rates, mortality rates, and maximum
rates of population growth, as well as mass dependence of population
density. However, the theory is restricted to relatively simple phenomena,
i.e., the effects of allometry, kinetics, and stoichiometry on the biological
processing of energy and materials, and even in this domain not all varia-
tion is explained (Brown et al.
2004
). The Principle of Computational
Equivalence implies that the theory cannot be developed to address
