Which of the following is not a characteristic of true species ?

Options

A. Members of a species can interbreed .
B. Gene flow does not occur between the population of a species.
C. Each species is reprouctively isolated from evey other species.
D. Variatins occur amongst members of a species.

Answer

To determine which of the following is not a characteristic of true species, we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding True Species**: A true species is defined by certain characteristics that allow its members to be classified as a distinct group. These characteristics typically include the ability to interbreed, reproductive isolation from other species, and genetic variation among members.

2. **Analyzing Option A**:
- **Statement**: Members of a species can interbreed.
- **Explanation**: This is a fundamental characteristic of true species. Members of the same species can reproduce and produce viable offspring.
- **Conclusion**: This statement is true for true species.

3. **Analyzing Option B**:
- **Statement**: Gene flow does not occur between the populations of species.
- **Explanation**: Gene flow refers to the transfer of genetic material between populations. It can occur between different populations of the same species or even between different species through hybridization. Therefore, stating that gene flow does not occur between populations of species is misleading.
- **Conclusion**: This statement is **not** a characteristic of true species, making it the correct answer.

4. **Analyzing Option C**:
- **Statement**: Each species is reproductively isolated from every other species.
- **Explanation**: Reproductive isolation is a key characteristic of true species, preventing interbreeding between different species. This statement is true.
- **Conclusion**: This statement is true for true species.

5. **Analyzing Option D**:
- **Statement**: Variations occur amongst the members of species.
- **Explanation**: Variations are indeed present within a species due to genetic differences. This is a characteristic of true species.
- **Conclusion**: This statement is true for true species.

### Final Answer:
The option that is **not a characteristic of true species** is **Option B**: Gene flow does not occur between the populations of species.

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