What are not known, however, are the fundamental and realized macronutrient niches (levels 3 and 4 above) of brown bear, which are important for understanding the relationships between their nutritional environments, adaptation, population persistence, and functional omnivory more generally. The fundamental macronutrient niche concept is also germane to understanding and implementing applied ecology, such as whether a population (or individual) is likely to persist in the face of substantial perturbations to its nutritional environment, due to factors such as climate change, translocation, and dispersal.