ADAPTIVE DYNAMICS
- an integrative framework for modelling frequency-dependent evolution -
> list of papers on adaptive dynamics <
The theory of adaptive dynamics provides
a framework for modelling evolution by natural selection in complex ecological
systems, where fitness depends on the frequencies of the interacting
phenotypes. This framework integrates and extends concepts and techniques from
evolutionary game theory, with special emphasis on dynamical phenomena such as
the origin and divergence of new lineages by evolutionary branching. The
general theory of adaptive dynamics yields algorithms that can readily be
applied to analyse concrete ecological settings.
The most intriguing phenomena discovered
is evolutionary branching, whereby a population that initially contains a
single phenotype splits up into two lineages with increasingly different
phenotypes. Evolutionary branching occurs at particular phenotypes (called
branching points) that are attractors of monomorphic evolution but are not evolutionarily
stable in the sense that are not immune to invasion by mutants. Near such a
phenotype, coexistence of very similar types (such as the original and its
mutant) is possible. Once the population has become dimorphic, selection is
disruptive and consequently the coexisting phenotypes undergo divergent
coevolution. Evolutionary branching is the clonal reminiscent of non-allopatric
speciation, and ecological systems where evolutionary branching occurs provide
the selective environment for speciation.
A great strength of adaptive dynamics is
its capability to incorporate ecological complexity and to model long-term
evolution as driven by ecological interactions. The theory of the ESS has been
enormously successful in analysing evolution in complex ecological and
behavioural interactions. Adaptive dynamics is an extension of the ESS-theory
that preserves its wide applicability to diverse ecological systems.
Applications already include models exploring the evolution of competitive and
predator-prey systems, mutualism, multiple habitats, temporally fluctuating
environments, host-parasite systems, sex allocation, seed ecology, dispersal
strategies, etc.
From the mathematical point of view,
adaptive dynamics deals with a novel type of stochastic dynamical systems, with
the unorthodox property of changing the number of state variables (evolving
phenotypes) by extinction and by evolutionary branching.
Genetic complexity is incorporated at
various levels ranging from simple clonal inheritance in many phenotypic models
to single-locus (or few-locus) diploid models and to the most realistic
multilocus individual-based simulations. The genetically explicit models
support the conclusions from the analytically more tractable phenotypic
approach. Most notably, several studies show that assortative mating can evolve
in the selective environment present during evolutionary branching, which thus
gives the first step towards the formation of new, reproductively isolated
species in sympatry.
At present, the theory of adaptive dynamics
is best developed for one-dimensional phenotypes and for monomorphic
populations. Intense research concentrates on multiple-trait evolution, on
coevolving multispecies communities, and on ecological systems with complex
population dynamics including multiple attractors and chaos. A bifurcation
theory of adaptive dynamics is currently being developed. New insights may be
expected from the analysis of genetic models, especially in sympatric
speciation and in the evolution of genetic systems.
For further information, see a list of papers on adaptive dynamics.
Other links: Adaptive
dynamics and the evolution of biodiversity (PDF, in Hungarian)