New species can be formed without geographical isolation through

Options

A. Random mating
B. Assortative mating
C. Inter-varietal breeding
D. All the above.

Answer

To answer the question "New species can be formed without geographical isolation through," we will analyze the options provided and determine which one is correct.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks how new species can arise without geographical isolation. Geographical isolation typically leads to speciation by preventing gene flow between populations.

2. **Evaluating the Options**:
- **Random Mating**: This refers to mating without any preference for phenotypes or genotypes. In random mating, individuals mate without regard to their traits, which does not promote the formation of new species. Therefore, this option is incorrect.

- **Assortative Mating**: This is a mating pattern where individuals with similar phenotypes mate more frequently than would be expected under random mating. This can lead to increased genetic similarity within a population and can contribute to speciation by reinforcing traits that are advantageous in a specific environment. Thus, this option is a strong candidate for the correct answer.

- **Inter-varietal Breeding**: This refers to the mating between different varieties of the same species. While it can lead to new combinations of traits, it does not necessarily lead to the formation of a new species without geographical isolation. This option is also incorrect.

3. **Conclusion**: After evaluating all the options, the correct answer is **assortative mating**, as it can lead to speciation by promoting the mating of similar individuals, thus enhancing certain traits within a population.

### Final Answer:
New species can be formed without geographical isolation through **assortative mating**.

---