Question

Diversity of habitat over the total landscape or geographical area is referred to as ..................

• A. Genetic diversity
• B. Alfa diversity
• C. Beta diversity
• D. Gamma diversity

Hint:

Whittaker's Biodiversity Scales:
- $\alpha$-diversity $\rightarrow$ Point/local scale (within a single habitat).
- $\beta$-diversity $\rightarrow$ Gradient scale (turnover between two habitats).
- $\gamma$-diversity $\rightarrow$ Landscape/regional scale (total geographic pool).

Answer 1

The Correct Option is D

Concept:
Biodiversity can be evaluated across multiple biological scales, ranging from allelic variations within a single population to regional landscape heterogeneity.
In 1960, ecologist Robert H. Whittaker formulated a spatial hierarchy of species diversity comprising alpha ($\alpha$), beta ($\beta$), and gamma ($\gamma$) diversity components.

Step 1: Characterization of Diversity Scales:
1. Genetic Diversity: Quantifies the heritable nucleotide and allelic variations present among individuals within a single species population or across different populations of that species.
2. Alpha ($\alpha$) Diversity: Refers to local diversity, representing species richness within a single homogenous community, site, or discrete ecosystem.
3. Beta ($\beta$) Diversity: Represents differentiation diversity, measuring the rate of species turnover or degree of change in taxonomic composition between distinct habitats or along an environmental gradient.
4. Gamma ($\gamma$) Diversity: Represents regional diversity. It measures the overall diversity of species and habitats across an entire geographical region or landscape. It integrates both the local alpha richness of individual patches and the beta turnover occurring between those patches:
\[ \gamma = \bar{\alpha} \times \beta \]

Step 2: Assessment of the Problem Statement:
The question explicitly asks for the metric that captures the "diversity of habitat over the total landscape or geographical area."
By Whittaker's definition, the total diversity assessed at the landscape or macro-geographical scale is gamma ($\gamma$) diversity.
Final Answer:
The total landscape or regional scale diversity is Gamma diversity, corresponding to option (D).