Answer :
Final answer:
A keystone species is crucial for maintaining biodiversity and structure within an ecosystem, and its removal can lead to major ecological changes.
Explanation:
An accurate description of a keystone species is a species whose presence is critical to maintaining biodiversity within an ecosystem and to upholding an ecological community's structure. A keystone species often has a disproportionate impact on its environment, such that its removal or introduction can lead to significant changes in the community structure and the types of species that live there.
For example, the intertidal sea star Pisaster ochraceus is a keystone species in the northwestern United States, preying on mussels. Its removal causes the mussel population to increase, which then leads to a reduction in biodiversity. Similarly, the banded tetra, a fish that supplies phosphorus to aquatic ecosystems, is another such keystone species whose extinction would greatly affect community structure.
