Negative frequency dependence and the importance of spatial scale

Issues of spatial scale are inherent in many ecological systems. This study uses a spatially explicit cellular automaton model to explore how the scale of dispersal interacts with the scale and strength of negative frequency dependence to determine patterns of species distribution. Counter to expectation, strong local frequency-dependent interactions result in random spatial patterns. When dispersal scale and interaction scale are decoupled, the resulting patterns are not necessarily random. For strong negative frequency dependence, stable bands result when the scale of interaction exceeds the scale of dispersal, and bands with two-point cycles result when the scale of dispersal exceeds the scale of interaction. However, for weaker interactions occurring over intermediate scales, only random patterns result. Thus, our results call into question the utility of inferring any ecological interaction from only the spatial distributions of the putatively interacting species. Furthermore, our results call for new experimental studies that explicitly manipulate the strength and the scale of the processes being studied.