In sigmoid grouth dN/dt=(b-d)N, where (b-d) is represented as

Options

A. intrinsic rate of natural increase
B. extrinsic rate of natural increase
C. morphological rate of natural increase
D. phenotypical rate of natural increase

Answer

To solve the question regarding the sigmoid growth model and the representation of (b-d) in the equation dN/dt = (b-d)N, follow these steps:

### Step-by-Step Solution:

1. **Understand the Equation**: The equation dN/dt = (b-d)N describes how the population size (N) changes over time (t). Here, dN/dt represents the rate of change of the population size.

2. **Identify the Terms**: In this equation:
- **b** represents the birth rate of the population.
- **d** represents the death rate of the population.
- Therefore, (b-d) represents the net change in the population due to births and deaths.

3. **Define (b-d)**: The term (b-d) is crucial as it indicates the overall growth potential of the population. When births exceed deaths, the population grows, and when deaths exceed births, the population declines.

4. **Relate to Growth Models**: In the context of population dynamics, particularly in logistic growth (sigmoid growth), (b-d) is referred to as the intrinsic rate of natural increase (r). This is because it reflects the potential for growth under ideal conditions before considering limiting factors.

5. **Conclusion**: Therefore, in the context of the sigmoid growth model, (b-d) is represented as the **intrinsic rate of natural increase**.

### Final Answer:
(b-d) is represented as the **intrinsic rate of natural increase**.

---