Contributed Session 2:  PDEs and Applications
On chaos, transient chaos and ghosts in single population models with Allee effects
Jorge Duarte
Instituto Superior de Engenharia de Lisboa
Portugal
  Co-Author(s):    
  Abstract:
 

Density-dependent effects, both positive or negative, can have an important impact on the population dynamics of species by modifying their population per-capita growth rates. An important type of such density-dependent factors is given by the so-called Allee effects, widely studied in theoretical population biology. The study of transient dynamical phenomena near bifurcation thresholds has attracted the interest of many researchers due to the relevance of bifurcations in different physical or biological systems. In the context of saddle-node bifurcations, where two or more fixed points collide annihilating each other, it is known that the dynamics can suffer the so-called delayed transition. This phenomenon emerges when the system spends a lot of time before reaching the remaining stable equilibrium, found after the bifurcation. The time delay scales according to an inverse square-root power law. In this work, we characterize analytically this scaling law using complex variable techniques for a family of one-dimensional maps. We show that the numerical results are in perfect agreement with the provided analytical solutions. The procedure presented in this work can be used to characterize the scaling laws of one-dimensional discrete dynamical systems with saddle-node bifurcations, particularly single population models with Allee effects.