The of a species is usually the result of predation, competition, and other types of interaction between species.

Realized Niche

Explanation:

Realized niche is also referred to as Post Competitive niche and can be defined as a thriving environmental area created by a group of organisms to survive from an exsisting Faundermental  niche where interactions (predation, competition, light, water,food) with other organisms were limited and competed for.  

For example. In a tree( Faundermental niche) which houses different species of birds, In order to survive, each specie of the birds will create a realized niche so as to survive from predation, competition, light etc which the whole tree provides.

what statement best describes the difference between the sympathetic and parasympathetic nervous systems?

the sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.