The world in a grain of soil: From species interactions to community structureSpecies are inter-dependent: their survival relies on the complex ecosystems in which they live. Whether the ecosystem in question is a rainforest or a coral reef, its diversity and stability depend critically on how individual species in these communities interact with one another. While awareness of biodiversity has increased, most people do not realize that hidden in our own backyards lie perhaps the most intricate ecosystems of all. The microscopic microbial worlds in the soil have a complexity and diversity that vastly exceeds that of anything visible to the human eye; even a single grain of soil can contain thousands of bacterial species living and interacting with one another. Some species in these communities make food, enabling their neighbors to survive. Others make poisons, such as antibiotics, killing neighboring bacteria or preventing them from growing. The victims of these attacks, in turn, fight back by evolving sophisticated defense systems to resist the poisons. These elaborate interactions between species ultimately hold together sophisticated microbial communities that play crucial roles in Earth's global ecology, including biomatter decomposition and nutrient cycling. Many crucial aspects of the world are indeed contained within a single grain of soil.
This unseen social world of bacteria has direct implications for our lives, even beyond its role in Earth's global ecology. The warfare between microbes in the soil is the ultimate source of antibiotics
