Which of the following is a keystone species?

Options

A. Fig
B. Deer
C. Mycorrhiza
D. Pollinator

Answer

To determine which of the following is a keystone species, we need to understand what a keystone species is and analyze the options provided.

### Step-by-Step Solution:

1. **Define Keystone Species**:
- A keystone species is one that has a disproportionately large impact on its environment relative to its abundance. These species play a critical role in maintaining the structure of an ecological community.

2. **Analyze the Options**:
- **Option 1: Fig (Ficus)**:
- Fig trees are known to provide food and shelter for a variety of species, including birds, bats, reptiles, and insects. They play a crucial role in the ecosystem by supporting numerous other species.
- **Option 2: Deer**:
- While deer are important herbivores in many ecosystems, they do not have the same level of impact on the structure of the ecosystem as keystone species do.
- **Option 3: Mycorrhiza**:
- Mycorrhizal fungi form symbiotic relationships with plant roots, aiding in nutrient absorption. However, they are not classified as keystone species themselves.
- **Option 4: Pollinator**:
- Pollinators are vital for the reproduction of many plants, but they are not typically classified as keystone species.

3. **Identify the Keystone Species**:
- Based on the analysis, the fig tree (Ficus) is the best example of a keystone species among the options provided. It supports a wide range of organisms and plays a significant role in the ecosystem.

4. **Conclusion**:
- Therefore, the correct answer is **Option 1: Fig**.