Explain reasons for differences in the realized niche and fundamental niche of an organism.

a. an ecological niche is an organism’s role/functional place in the environment

b. the fundamental niche is the potential niche and the realized niche is the actual niche

c. includes habitat/feeding/how it survives

d. limiting factors play a part on the actual distribution of species

e. competition prevents species occupying their fundamental niche

f. species show competitive exclusion

    OR

    two species cannot occupy the same niche in an ecosystem

g. «in competitive exclusion» one species will replace the other species

The answers given in the markscheme may be awarded if the candidate explains a suitable example

For marking point g, do not accept “one species becomes extinct” as a standalone answer unless it is clear they
are referring only to the ecosystem under discussion

[Max 4 Marks]