The Nicholson–Bailey model was developed in the 1930s to describe the population dynamics of a coupled host-parasite (or predator-prey) system. It is named after Alexander John Nicholson and Victor Albert Bailey.
The model uses difference equations to describe the population growth of host-parasite populations. The model assumes that parasites search for hosts at random, and that both parasites and hosts are assumed to be distributed in a non-contiguous ("clumped") fashion in the environment.
In its original form, the model does not allow for stable host-parasite interactions. To add stability, the model has been extensively modified to add new elements of host and parasite biology. The model is closely related to the Lotka–Volterra model, which uses differential equations to describe stable host-parasite dynamics.
A credible, simple alternative to the Lotka-Volterra predator-prey model and its common prey dependent generalizations (like Nicholson-Bailey) is the ratio-dependent or Arditi-Ginzburg model. The two are the extremes of the spectrum of predator interference models. According to the authors of the alternative view, the data show that true interactions in nature are so far from the Lotka-Volterra extreme on the interference spectrum that the model can simply be discounted as wrong. They are much closer to the ratio dependent extreme, so if a simple model is needed one can use the Arditi-Ginzburg model as the first approximation.
- Arditi, R. and Ginzburg, L.R. (1989) "Coupling in predator-prey dynamics: ratio dependence" Journal of Theoretical Biology, 139: 311–326.
- Arditi, R. and Ginzburg, L.R. (2012) How Species Interact: Altering the Standard View on Trophic Ecology Oxford University Press. ISBN 9780199913831.
- J. L. Hopper, "Opportunities and Handicaps of Antipodean Scientists: A. J. Nicholson and V. A. Bailey on the Balance of Animal Populations," Historical Records of Australian Science 7(2), pp. 179–188, 1987.