What characterizes stable equilibrium?

Stable equilibrium is characterized by the presence of negative feedback mechanisms, which play a crucial role in maintaining the balance within a system. When a system experiences a disturbance, negative feedback acts to counteract that change, helping to restore the system to its original state of equilibrium. This dynamic allows ecosystems, for example, to recover from fluctuations such as changes in population sizes due to predation, resource availability, or environmental conditions.

For instance, in an ecosystem where a predator population increases, the prey population may decline as a result. This decrease in prey will eventually lead to a reduction in the predator population due to a lack of food. Thus, the negative feedback loop helps to stabilize both populations, returning them toward their previous equilibrium levels.

The other choices highlight aspects that do not contribute to a stable equilibrium. The absence of feedback in a system would result in instability, as there would be no mechanism to correct deviations from equilibrium. Positive feedback mechanisms, on the other hand, amplify changes and drive a system away from equilibrium, leading to potential collapse rather than stability. Constant alterations in species diversity may indicate a dynamic ecosystem but do not inherently contribute to a stable equilibrium, as they suggest ongoing changes rather than a return to balance.