In every ecosystem, there’s at least something that is very limited – sunlight, water, nutrients, or space. How species compete for limited resources is fundamental to how ecosystems function.

The ecology of competition

We all know the type: a super competitive classmate who always wanted to know how fast you could run your kilometre (and if they beat you) or what score you made on your test (and if you scored higher than them). In this context, competition can have a negative connotation But more broadly, competition is a fact of life: life on Earth relies on species interacting with each other, and that includes competing against each other.

Ecologists define competition as a type of species interaction that is harmful to both parties. In other words, it would be better for one of two parties if the other one wasn’t there. However, competition exists pretty much everywhere – from big ecosystems to very small structures – which means that life has to compete for resources like light, water, nutrients, or space to survive.

Competition and biodiversity: between stability and fragility

Even though competition is tough on individual species, it can benefit the broader ecosystem. Competition can promote biodiversity through niche partitioning: organisms occupy different niches (“jobs”) while competing for resources. Through competing, redundant organisms that are similar often go (locally) extinct. What’s left is a system with organisms that all have different niches. Competition weeds out redundancy.

But weeding out all redundancy may also affect the stability and resilience of an ecosystem: too much competition can make ecosystems more fragile because there may be no redundant parts anymore that could fill a specific niche if a species goes extinct. This could even lead to the collapse of a community.

From local communities to global patterns

A certain amount of competition is fundamental for healthy ecosystems. Competition not only influences which species survive, but also what traits they have and how functionally unique they are. In short: competition structures much of our co-existence on Earth. Traditionally, these competition dynamics are studied at an ecological community level. As a global ecology lab, however, we are studying what competition means for global patterns of biodiversity.

There are still many things we don’t fully understand: in which regions does competition promote biodiversity and in which does it limit biodiversity? Where and how is competition an especially strong structuring force? In every ecosystem there are homogenising as well as diversifying forces —  and that is due to environmental factors as well as species interactions, like competition. We want to know how much of these diversity patterns we can attribute to competition. Lead Scientist Daniel Maynard’s latest paper, for example, looks at functional tree traits and identifies a set of traits most apt to explain global biodiversity patterns for trees.

Ecosystem restoration is the art of understanding and managing competition

Untangling abiotic factors, such as temperature or water availability, from biotic factors, like competition, is also useful for global ecosystem restoration. In the face of biodiversity loss and climate change, efforts to bring degraded ecosystems back to life should be mindful to restore reservoirs of biodiversity. But the way there can be long and difficult, taking several phases, years, and decades.

To understand the ecological succession of an ecosystem therefore means to understand how competition works over time: to know at which stage competition between seedlings may hinder the overall restoration process and at which stage it can facilitate more diversity. It is to know when to intervene and when to hold back. Big data is of particular help because it allows us to model succession trajectories further into the future than experiments could.

Even so, ecosystems and the manifold interactions between its organisms – from mutualism to competition – are fascinatingly complex and have not yet been captured in their entirety by mathematical models. While fundamental concepts like competition have been discussed since the times of Ancient Greece, there is still much to learn and discover.