How target waves emerge in population dynamics
  Based on a multi-agent model, we investigate how target waves emerge from a population dynamics with cyclical interactions among three species. We show that the periodically injecting source in a small central area can generate target waves in a two-dimensional lattice system. By detecting the temporal period of species' concentration at the central area, three modes of target waves can be distinguished. Those different modes result from the competition between local and global oscillations induced by cyclical interactions: Mode A corresponds to a synchronization of local and global oscillations, Mode B results from an intermittent synchronization, and Mode C corresponds to the case when the frequency of the local oscillation is much higher than that of the global oscillation. This work provides insights into pattern formation in biologic and ecologic systems that are totally different from the extensively studied diffusion systems driven by chemical reactions. 
Luo-Luo Jiang, Tao Zhou, Xin Huang, Bing-Hong Wang