Before You Begin
Question #46448
The Question
Alexander von Humboldt's species-area relationship (log S = log C + Z log A) can be conceptually linked to Darwinian adaptive radiation. Which of the following statements regarding this ecological and evolutionary integration is INCORRECT?
Options
- A.
For smaller regions, the Z-value generally lies between 0.1 and 0.2, reflecting a lower rate of species addition due to limited spatial geometry and fewer isolated niches for radiation.
- B.
When analyzing entire continents, the Z-value steepens to a range of 0.6 to 1.2, as massive geographical scales provide diverse, isolated niches that facilitate extensive adaptive radiation.
- C.
A Z-value of 1.15, as observed in frugivorous birds of tropical forests, indicates highly restricted adaptive radiation caused by intense interspecific competition within a confined geographical area.
- D.
In the logarithmic equation, the Z-value (regression coefficient) effectively represents the rate at which new species are encountered as the geographical area and its associated niches expand.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Adaptive Radiation Logic|Species-Area Relationship|Z-value in Large Areas
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize NCERT Z-values (0.1-0.2, 0.6-1.2, 1.15) without understanding the ecological geometry behind the slope.
A steeper slope (higher Z-value) mathematically represents a rapid accumulation of species as area increases.
This is biologically driven by the availability of diverse niches on a continental scale, which fuels adaptive radiation.
Option C acts as a 'Functional Confusion' trap by associating a high Z-value (1.15) with 'restricted radiation' and a 'confined area', which directly contradicts both the mathematical meaning of a steep slope and the NCERT fact that this value applies to entire continents.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Evolution - Class 12 |
| Concept | Adaptive Radiation Logic |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |