Reason of fast speciation in present day crop plant is :

Options

A. Mutation theory
B. Isolation
C. Polyloidy
D. Sexual reproduction.

Answer

To solve the question regarding the reason for fast speciation in present-day crop plants, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Speciation**: Speciation refers to the process by which new species arise. In the context of crop plants, this can happen rapidly due to various factors.

2. **Identifying the Options**: The options given are:
- Mutation Theory
- Isolation
- Polyploidy
- Sexual Reproduction

3. **Analyzing Polyploidy**:
- Polyploidy is the condition where an organism has more than two complete sets of chromosomes.
- It is a common phenomenon in plants and can lead to the development of new species.

4. **Mechanism of Polyploidy**:
- Polyploidy often occurs due to errors during cell division, specifically during the anaphase stage of meiosis, where chromosomes fail to separate properly.
- This results in gametes that have an abnormal number of chromosomes, leading to offspring that are genetically distinct from their parents.

5. **Reproductive Isolation**:
- Polyploidy can create reproductive isolation because polyploid individuals cannot successfully breed with their diploid relatives, leading to a new gene pool.
- This isolation is crucial for speciation as it prevents gene flow between the new polyploid species and the original species.

6. **Conclusion**:
- Given that polyploidy leads to rapid speciation through the creation of new species that are reproductively isolated from their parent species, it is the correct answer to the question.

### Final Answer:
The reason for fast speciation in present-day crop plants is **polyploidy**.

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