From the Mima mounds of Washington state to the famous “fairy circles” in southwestern Africa, scientists have long debated how self-organized regular patterns of plant growth come into formation in so many desert and grassland landscapes.
A theory put forth by a Princeton-led research team suggests that instead of a single overarching cause, large-scale vegetation patterns in arid ecosystems could occasionally stem from millions of local interactions among neighboring plants and animals.
Satellite images from four continents showed that insect nests are often remarkably evenly spaced, with each nest having an average of six neighbors. The researchers used mathematical models and computer simulations to show that territorial aggression between adjacent colonies can produce this arrangement.
Individual colonies spread outward until they encounter and fight with their neighbors, occasionally killing off smaller colonies. Over time, this leads to a mosaic of hexagonal territories. Each of the six sides represents the frontline between a colony and its enemies next door.
The honeycomb formations provide the optimal partitioning of space among the different colonies — and plant growth is affected by these activities.
Many patterns throughout the world — from fish territories to the spatial arrangement of bird nests — likely result from territorial aggression.