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Problem 2 - Entrance Test

Which of the following statements about the species-area relationship is correct?

A. The relationship is linear on a logarithmic scaleB. The slope (z-value) is always 0.5 for all habitatsC. Islands closer to the mainland have lower species richness than distant islandsD. The relationship does not hold for very large areas exceeding biogeographic regions

Correct: D

The species-area relationship is a power function: S = cA^z, where S is species richness, A is area, and z is the slope. When plotted on a log-log scale, the relationship becomes linear. However, the z-value varies depending on habitat type and isolation; it is not always 0.5. The species-island relationship states that larger and less isolated islands have higher species richness (Island Biogeography Theory by MacArthur and Wilson), so distant islands generally have lower species richness than closer ones. The relationship does hold for large areas and is used to predict species loss due to habitat fragmentation.