Question

The term alpha diversity refers to
A) Genetic diversity
B) Community and ecosystem diversity
C) Species diversity
D) Diversity among the plants

Answer 1

In 1972, R.H. Whittaker introduced the terms alpha, beta and gamma diversity to measure biodiversity over geographic scales. He was the first to incorporate the concept of biotic diversity in three different aspects or levels.

Complete answer:
Alpha diversity was defined by Whittakar (1972) and it was expressed in terms of the number of species or species richness in an ecosystem. It refers to the biological diversity within a particular area, community or ecosystem. Thus the alpha diversity can be measured by counting the distinct group of different living organisms or species within the particular habitat or ecosystem on the basis of the structure of the community.

So, the correct answer is option B: 'Community and ecosystem diversity'.

Additional Information: Biodiversity is the term that usually refers to the variety and variability of all species and living organisms, and the ecosystems that connect them.
The biological diversity is broadly classified into three different levels —Species diversity, Genetic diversity and Community or Ecosystem diversity.
Species diversity – variety of species within a particular habitat. It refers to the diversity among species.
Genetic diversity – variation or diversity of genetic materials among the populations and the individuals of the same species. It refers to diversity of genes within the species or different species.
Ecosystem diversity – the diversity of habitats or types of community within the ecosystem, including abiotic and biotic components. The ecosystem diversity can also be referred as Community diversity.
Whittaker (1972) in his book, Evolution and measurement of species diversity proposed his most influential biodiversity concept. He distinguished three aspects or levels of species diversity in natural communities for measuring biodiversity over spatial scales.
Alpha diversity, present within community diversity which is measured by counting the number of species in that ecosystem.
Beta diversity is defined as the quantitative measurement to compare the diversity of species between ecosystems.
Gamma diversity is a measure of overall diversity of species richness for different ecosystems within a large region.

Note: There are several ways to measure the biodiversity such as species richness, species evenness, genetic diversity; phenotypic variance and population number. Of these, Species richness and evenness are the two prominent factors used for measuring diversity.