Assertion : If the species-area relationship are analysed among very large areas like the entire continents, the value of Z, i.e., slope of line in the range of 0.1 to 0.2.
Reason : The value of Z, i.e., slope of line of species area relationship lies in the range of 0.6 to 1.2 when analysis is done among small areas.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

D

Explanation

Alexander von Humboldt observed that within a region, species richness (number of species per unit area) increases with increasing explored area, but only upto a limit. The relationship between species richness and area turned out to be rectangular hyperbola for a wide variety of texa such as birds, bats, freshwater fish or flowering plants. On a logerithmic scale, the relationship is a straight line.
`log S = log C+Z log A`
Here S is species richness, Z is slope of line or regression coefficient, C is Y intercept while A is area.
The value of Z, i.e., slope of line (regression coefficient) of species-area relationships is similar and lies in the range of 0.1 to 0.2 when analysis is done among small areas. However, if the species area relationship is for very large areas like entire continent, the slope of the line is much steep with value of Z in the range of 0.6 to 1.2, e.g., frugivorous birds and mammals of tropical forests of different continents with a steeper line of 1.15. Thus larger the explored area, more is steepness of the slope of line.