Mammals from colder climates generally have shorter ears and limbo to minimize heat loss. This is called

Options

A. Bergman's rule
B. Glover's rule
C. Allen's rule
D. Jordan's rule

Answer

To solve the question regarding why mammals from colder climates have shorter ears and limbs to minimize heat loss, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**:
The question states that mammals in colder climates have shorter ears and limbs to minimize heat loss. We need to identify the rule that describes this phenomenon.

2. **Identifying Relevant Concepts**:
- **Thermoregulation**: This is the process by which organisms maintain their body temperature within certain boundaries, even when the surrounding temperature is very different.
- **Heat Loss**: Heat loss in animals is influenced by their surface area. The greater the surface area relative to volume, the more heat is lost.

3. **Analyzing the Options**:
- **A. Bergman's Rule**: This rule states that within a species, individuals in colder climates tend to be larger than those in warmer climates. It relates to body size, not limb or ear length.
- **B. Glover's Rule**: This is not a widely recognized biological rule related to temperature adaptation.
- **C. Allen's Rule**: This rule states that endothermic animals (warm-blooded) from colder climates tend to have shorter limbs and ears compared to those from warmer climates to minimize heat loss.
- **D. Jordan's Rule**: This rule pertains to the number of vertebrae in fish and is not relevant to mammals or thermoregulation.

4. **Conclusion**:
Based on the definitions and the analysis of the options, the correct answer is **C. Allen's rule**. This rule specifically addresses the adaptation of mammals in colder climates with shorter extremities to reduce heat loss.

### Final Answer:
**C. Allen's rule**