Answer :
Final answer:
A keystone species is crucial for maintaining biodiversity and ecological structure, exemplified by the Pisaster ochraceus starfish. Robert Paine showed that removing this starfish from its environment disrupts the ecosystem by allowing mussel populations to overwhelm other species, thereby reducing diversity.
Explanation:
Keystone Species
A keystone species is one whose presence is critical for maintaining biodiversity within an ecosystem and the structure of an ecological community. The sea star, Pisaster ochraceus, found along the northwestern coast of the United States, is an iconic example of a keystone species. Ecologist Robert Paine conducted experiments which proved that removing Pisaster ochraceus from its environment led to an increase in mussel populations, the starfish's prey, which in turn disrupted the species composition and lowered biodiversity. Paine's work highlighted how the presence of a single species can have a disproportionately large effect on its ecosystem.
