The species-area relationships among very large areas like entire continents

Options

A. The slope of the line to be much steeper
B. Z values lies in the range of 0.1 to 0.2
C. Z values lies in the range of 0.6 to 1.2
D. Both A and C

Explanation

### Step-by-Step Solution:

1. **Understanding Species-Area Relationship**:
The species-area relationship describes how the number of species (species richness) increases with the area surveyed. This relationship is often represented graphically.

2. **Graphing the Relationship**:
- On the x-axis, we plot the area (A).
- On the y-axis, we plot species richness (S).
- The resulting graph typically forms a rectangular hyperbola.

3. **Mathematical Representation**:
The relationship can be mathematically expressed as:
\[ S = cA^z \]
where:
- \( S \) = species richness
- \( A \) = area
- \( c \) = a constant (y-intercept)
- \( z \) = slope of the curve

4. **Logarithmic Transformation**:
When we take the logarithm of both sides, the equation transforms to:
\[ \log S = \log c + z \log A \]
This results in a straight line on a log-log scale.

5. **Interpreting the Variables**:
- \( S \) represents species richness.
- \( A \) represents area.
- \( c \) is the y-intercept.
- \( z \) is the slope of the line.

6. **Behavior of the Slope (z)**:
- For most areas, the value of \( z \) remains consistent and falls between 0.1 and 0.2.
- However, when considering very large areas, such as entire continents, the slope \( z \) tends to increase, making the line steeper.

7. **Conclusion**:
- When analyzing very large areas, the slope of the species-area relationship becomes steeper, indicating that species richness increases more rapidly with area.
- Therefore, the correct options regarding the behavior of the species-area relationship for large areas are:
- A: The slope becomes steep.
- C: The value of \( z \) can range from 0.6 to 1.2.

### Final Answer:
Both options A and C are correct when considering the species-area relationship for very large areas like entire continents.

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