An organism that has particularly far-reaching impacts on community structure is called a(n) .

Keystone Species

Explanation:

Some organisms of particular species are said to be keystone species as they regulate the structure and function of the whole community. These organisms greatly affect the other species present in the community. Organisms of keystone species are not the most abundant ones in the community but affect the availability of important resources such as food, water, etc. to the members of the other species of the community.

Fig trees in the tropical rain forest of America serve as keystone species as they provide food to fruit-eating animal species such as bats, monkeys specifically when the fruits of other tree species are not available.