Name:_______________________ Date:________ Period:___
Barnacles and Ecological Niches
A niche refers to all the resources that a species uses in its environment, including both biotic and abiotic
factors. No two species can occupy the same niche. This is known as the Competitive Exclusion
Principle.
Two different species of barnacles were introduced together on to a rock platform in an intertidal zone.
When observed growing separately the population numbers were high.
The population of barnacles was collected and recorded over a 17-month period.
Data is shown in the table below.
1. On the next page draw a graph of the tabled data.
2. State which species had the advantage over the first three months.
3. State the species that had the competitive advantage over the 17 months.
4. Explain how the data supports the competitive exclusion principle.
5. The two barnacle species can both survive on lower rocks but only species A actually does so, with
species B adopting a higher zone. Account for this niche separation by describing the difference between
fundamental (expected) and realized (actual) niches.