The loss of biodiversity limits ecosystems' evolutionary potential to continue to produce new, therapeutic plant varieties, as well as missing out on potentially useful compounds that are lost before the species that bear them have been recorded. That is, biodiversity can increase overall ecosystem stability when biodiversity is low, and decrease it when biodiversity is high, or the opposite with a U-shaped relationship. The two key components of ecosystem stability are resilience and resistance. Resistance is an ecosystem's ability to remain stable when confronted with a disturbance. Resilience is the speed at which an ecosystem recovers from a disturbance. Ecosystem stability is the ability of an ecosystem to maintain a steady state, even after a stress or disturbance has occurred. In order for an ecosystem to be considered stable, it needs to have mechanisms in place that help it return to its original state after a disturbance occurs.