Keystone Species
Biology: IB Diploma Higher Level, topic 4.1.2
Keystone Species
A keystone species is one whose presence is key to maintaining biodiversity within an ecosystem and to upholding an ecological community’s structure.
Keystone species - sea star
- The intertidal sea star, Pisaster ochraceus, of the northwestern United States is a keystone species.
- Studies have shown that when this organism is removed from communities, populations of their natural prey (mussels) increase, completely altering the species composition and reducing biodiversity.
Keystone species - banded tetra
- Another keystone species is the banded tetra.
- The banded tetra is a fish in tropical streams, which supplies nearly all of the phosphorus, a necessary inorganic nutrient, to the rest of the community.
- If these fish were to become extinct, the community would be greatly affected.
Test yourself on Keystone Species
What is the MOST likely outcome of removing a keystone species from an ecosystem?
Beavers are often considered a keystone species. Which of the following reasons provides the best justification for the classification of beavers as a keystone species?