Population are said to be sympatric when

Options

A. two populations live together and freely interbreed to produce sterile offspring
B. two populations are physically isolated by natural barriers
C. two populations are isolated but occasionally come together to interbreed
D. two pupulations share the same environment but cannot interbreed

Answer

To determine when populations are said to be sympatric, we need to understand the concept of sympatric speciation. Here’s a step-by-step solution to the question:

### Step-by-Step Solution:

1. **Definition of Sympatric Populations**: Sympatric populations are groups of organisms that live in the same geographic area and are capable of encountering one another.

2. **Interbreeding Criteria**: For populations to be classified as sympatric, they must have the potential to interbreed. However, in sympatric speciation, they do not interbreed due to various reproductive barriers.

3. **Analyzing the Options**:
- **Option A**: Two populations live together and freely interbreed to produce sterile offspring.
- This is incorrect because if they freely interbreed, they are not sympatric in the context of speciation.
- **Option B**: Two populations are physically isolated by natural barriers.
- This is incorrect as sympatric populations are not physically isolated; they share the same environment.
- **Option C**: Two populations are isolated but occasionally come together to interbreed.
- This is incorrect because if they occasionally interbreed, they are not fully sympatric.
- **Option D**: Two populations share the same environment but cannot interbreed.
- This is the correct option, as it defines sympatric populations accurately.

4. **Conclusion**: Therefore, populations are said to be sympatric when they share the same environment but cannot interbreed.

### Final Answer:
Populations are said to be sympatric when **two populations share the same environment but cannot interbreed**.

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