What characteristic makes an organism a keystone species in an ecosystem?

• A. It is the primary producer in the ecosystem.
• B. It is the most abundant species in the ecosystem.
• C. It has a disproportionately large impact on its environment relative to its abundance.
• D. It is the largest predator in the ecosystem.

Answer: (C)

Verified step by step guidance

1. Understand the concept of a keystone species: A keystone species is one that has a disproportionately large impact on its ecosystem relative to its abundance. This means that even if the species is not the most numerous, its presence and role are crucial for the structure and functioning of the ecosystem.
2. Differentiate between keystone species and other roles: Unlike primary producers, which are the main source of energy for an ecosystem, or the most abundant species, which are simply present in large numbers, a keystone species plays a critical role that affects many other organisms in the ecosystem.
3. Consider the ecological impact: A keystone species can influence the types and numbers of various other species in a community, often by controlling populations of other species, thus maintaining the balance and diversity of the ecosystem.
4. Evaluate examples of keystone species: Examples include sea otters, which control sea urchin populations and thus protect kelp forests, or wolves in Yellowstone, which regulate prey populations and have cascading effects on the ecosystem.
5. Recognize the importance of keystone species conservation: Because of their significant role, the loss of a keystone species can lead to dramatic changes in the ecosystem, highlighting the importance of their conservation for maintaining ecological balance.