In ecology, the term biodiversity refers to which combination of genetic variation and species variety within habitats?

Introduction / Context:
Biodiversity is a core concept in ecology and environmental science, frequently mentioned in discussions about conservation, climate change, and sustainable development. The term does not just refer to the number of species in an area. It has a broader meaning that also includes the variation of genes within a species and the diversity of ecosystems. Many exam questions test whether learners understand that biodiversity is multi level, rather than a simple species count. This question focuses on whether biodiversity covers both genetic variation and species richness within habitats.

Given Data / Assumptions:
- Option A mentions the range of genetic variation within a population.
- Option B mentions the total number of different species within a habitat.
- Option C combines both of these aspects, and option D rejects them.
- Standard definitions of biodiversity from textbooks and conservation literature are assumed.

Concept / Approach:
Biodiversity is usually described at three main levels. Genetic diversity refers to the variety of genes and alleles within a species or population. Species diversity refers to the number of species and their relative abundance in a given area. Ecosystem diversity refers to the variety of habitats, communities, and ecological processes in the biosphere. When people talk about conserving biodiversity, they often emphasise both genetic and species diversity because both are essential for the resilience and adaptability of life. Therefore, a correct understanding of biodiversity must include both the range of genetic variation and the number of species in a habitat.

Step-by-Step Solution:
1. Recall that biodiversity is short for biological diversity and reflects the variety of life at different levels. 2. Recognise that genetic diversity is the variation of genes and alleles within a population or species. 3. Recognise that species diversity is the count and relative abundance of different species within a habitat or region. 4. Understand that both genetic and species diversity are standard parts of formal definitions of biodiversity. 5. Conclude that biodiversity, in this question context, refers to both the range of genetic variation and the total number of species, so the combined option is correct.

Verification / Alternative check:
If you check major ecology or environmental science textbooks, you will see that biodiversity is defined broadly. For example, discussions on conservation biology stress that losing genetic diversity within a species can be as serious as losing entire species, because genetic diversity allows populations to adapt to changing conditions. At the same time, species richness is used as a common measure of biodiversity in different ecosystems. Some sources also include ecosystem diversity, but they almost always agree that both genetic and species diversity are important components. This supports the view that both option A and option B reflect parts of biodiversity.

Why Other Options Are Wrong:
Range of genetic variation within a population: This is only one level of biodiversity, namely genetic diversity, and does not fully capture the term on its own.
Total number of different species within a habitat: This focuses on species diversity only and ignores genetic variation within each species, so it is incomplete.
None of the above: This is wrong because both genetic variation and species richness are recognised elements of biodiversity in standard definitions.

Common Pitfalls:
Many learners equate biodiversity solely with the number of species, because species counts are easy to visualise and measure. This can lead them to choose only option B. Others may focus only on genetic diversity if they have recently studied evolution and natural selection. The key is to remember that biodiversity is multi dimensional. Ignoring genetic variation can underestimate how much diversity is actually present and how resilient a population may be to diseases or environmental changes. Thinking in terms of multiple levels helps avoid oversimplifying this important concept.

Final Answer:
The term biodiversity in this context refers to both the range of genetic variation within a population and the total number of different species within a habitat.