Artificial selection to obtain cows yielding higher milk output represents

Options

A. (a) Stabilizing selection as it stabilizes a character in the population.
B. (b) Directional selection as it pushes the mean of a character in one direction
C. (c) Disruptive selection as it splits the population into the one yielding higher output and the other lower output
D. (d) Stabilizing followed by disruptive selection as stabilizes the population to produce high yielding cows.

Answer

To answer the question "Artificial selection to obtain cows yielding higher milk output represents," we can analyze the concept of artificial selection and its relation to the types of natural selection. Here’s a step-by-step breakdown of the solution:

### Step-by-Step Solution:

1. **Understanding Artificial Selection**:
- Artificial selection is a process where humans selectively breed organisms for specific traits. In this case, farmers breed cows that produce higher milk output.

**Hint**: Think about how humans influence the breeding process compared to natural selection.

2. **Identifying the Trait**:
- The desired trait in this scenario is "higher milk output," which is a phenotypic characteristic of the cows.

**Hint**: Consider what specific characteristic is being targeted for improvement in the cows.

3. **Types of Selection**:
- There are three main types of natural selection: directional, stabilizing, and disruptive selection.
- **Directional Selection**: Favors one extreme phenotype over others, leading to a shift in the population's traits in one direction.
- **Stabilizing Selection**: Favors the average phenotype and reduces variation, leading to a population that is more uniform.
- **Disruptive Selection**: Favors extreme phenotypes at both ends of the spectrum, potentially leading to two distinct groups within the population.

**Hint**: Recall the definitions of each type of selection and think about how they apply to the breeding of cows.

4. **Analyzing the Example**:
- In the case of cows yielding higher milk output, the selection process is favoring the extreme phenotype (high milk output) over others (lower milk output).
- This aligns with the definition of directional selection, where one extreme trait is favored.

**Hint**: Visualize the population before and after selection to see how the trait distribution changes.

5. **Conclusion**:
- Since artificial selection for higher milk output favors one extreme (high milk yield), it represents **directional selection**.

**Hint**: Reflect on how the breeding process changes the average trait in the population over time.

### Final Answer:
Artificial selection to obtain cows yielding higher milk output represents **directional selection**.