Dynamics of populations on the verge of extinction


  • Beáta Oborny, Géza Meszéna and György Szabó

B. Oborny, Dept of Plant Taxonomy and Ecology, Loránd Eötvös Univ., Pázmány Péter stny. 1/C, HU-1117, Budapest, Hungary (beata@ludens.elte.hu). – G. Meszéna, Dept of Biological Physics, Loránd Eötvös Univ., Pázmány Péter stny. 1/A, HU-1117, Budapest, Hungary. – G. Szabó, Research Institute for Technical Physics and Materials Science, P.O.Box 49, HU-1525, Budapest, Hungary.


Theoretical considerations suggest that extinction in dispersal-limited populations is necessarily a threshold-like process that is analogous to a critical phase transition in physics. We use this analogy to find robust, common features in the dynamics of extinctions, and suggest early warning signals which may indicate that a population is endangered. As the critical threshold of extinction is approached, the population spontaneously fragments into discrete subpopulations and, consequently, density regulation fails. The population size declines and its spatial variance diverges according to scaling laws. Therefore, we can make robust predictions exactly in the range where prognosis is vital, on the verge of extinction.