Assertion : Alpha diversity is said to be higher if the dissimilarity between communities is higher.
Reason : Alpha diversity is a measure of diversity between the communities.

Options

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

Answer

D

Explanation

The occurrence of different kinds of organisms reflects the biological diversity. The term biodiversity refers to the totality of genes, species, and ecosystem of a region. Biodiversity includes three hierarchial levels : (i) Genetic diversity (ii) Species diversity (iii) Community and ecosystem diversity. Diversity at the level of community and ecosystem has three perspectives which are called Alpha, Beta and Gamma diversity. Alpha diversity (within-community diversity) refers to the diversity of organisms sharing the same sommunity/habitat. A combination of species richness and equitability/evenness is used to represent diversity within a community or habitat. Species richness is the number of species per unit area. The number of apecies increases with the area of the site. Generally, greater the species richness, greater is the species diversity. However, number of individuals among the species may also vary, resulting into differnces in evenness or equitability and consequently in diversity. Species frequently change when habitat or community changes. The rate of replacement of species along a gradient of habitats of communities is called beta diversity (between-community diversity). Higher the heterogencity in the habitats in a region or greater the dissimilarity between communities, higher is the beta diversity. Diversity of the habitats over the total landscape or geographical area is called gamma diversity.