To better understand what we observe in the world, we need to know more about what is absent. This is a hypothesis of Estonian ecologists Meelis Pärtel, Robert Szava-Kovats, and Martin Zobel, who call the portions of species pools missing from study sites “dark diversity.” Think of it as analogous to dark matter, the invisible mass that physicists hypothesize accounts for the bulk of matter-energy in the vast expanse of space. Dark diversity serves a similar function: “Just as dark matter is important to understanding the structure of galaxies, dark diversity is necessary to understand ecosystems,” Pärtel explains.
The researchers, from the Institute of Ecology and Earth Sciences at the University of Tartu, described their hypothesis in the journal Trends in Ecology & Evolution. They argue that dark diversity does several things that most theories don’t. It offers an evolutionary background for a local habitat and its species, specifically those that have disappeared or been displaced. It’s a useful concept for understanding processes underlying diversity patterns. Most important, it can warn of current threats of extinction. That is, by reconstructing the multiplicity of organisms no longer present in a habitat, dark diversity can help scientists unlock the “restoration potential” of degraded ecosystems.
