Question 1

What is Simpson's Index of Diversity and how do I calculate it?

Accepted Answer

Simpson's Index (D) measures the probability that two individuals randomly selected from a sample belong to different species. The formula is D = 1 - Σ(n/N)², where n is the number of individuals of a particular species and N is the total number of individuals. A value close to 1 indicates high diversity, while 0 indicates no diversity. For example, if you have 10 individuals of species A and 10 of species B, N=20, Σ(n/N)² = (10/20)² + (10/20)² = 0.25+0.25=0.5, so D=0.5.

Question 2

Why is genetic diversity important for a species?

Accepted Answer

Genetic diversity allows populations to adapt to changing environments, such as new diseases or climate shifts. It provides the raw material for natural selection. Low genetic diversity, as seen in cheetahs or some crop plants, makes species vulnerable to extinction because they lack the variation needed to survive new threats. In conservation, maintaining genetic diversity is a key goal to ensure long-term survival.

Question 3

What is the difference between in-situ and ex-situ conservation?

Accepted Answer

In-situ conservation protects species in their natural habitats, e.g., national parks, marine reserves. It maintains ecosystem processes and allows species to evolve naturally. Ex-situ conservation involves protecting species outside their habitats, e.g., zoos, seed banks, captive breeding. It is used when in-situ is no longer possible or as a backup. Both have pros and cons: in-situ is more holistic but may not protect against all threats; ex-situ can save species from immediate extinction but may not preserve natural behaviours.

Question 4

How do you measure biodiversity in a habitat?

Accepted Answer

Biodiversity is measured using species richness (number of species) and species evenness (distribution of individuals). Ecologists use sampling techniques like quadrats (for stationary organisms) and transects (to study changes across an area). They calculate indices like Simpson's Index to quantify diversity. For genetic diversity, they analyse DNA sequences or allele frequencies. For ecosystem diversity, they map different habitat types and assess their extent and connectivity.

Question 5

What are the main threats to biodiversity?

Accepted Answer

The main threats are habitat destruction (e.g., deforestation, urbanisation), overexploitation (e.g., overfishing, hunting), pollution (e.g., pesticides, plastic waste), climate change (altering habitats and life cycles), and invasive species (outcompeting natives). These often interact, making conservation complex. For example, climate change can exacerbate habitat loss by shifting suitable ranges.

Question 6

How does biodiversity affect ecosystem services?

Accepted Answer

Biodiversity underpins ecosystem services like pollination, nutrient cycling, water purification, and climate regulation. Higher biodiversity often increases ecosystem productivity and stability. For instance, diverse plant communities are more resilient to pests and droughts. Loss of biodiversity can disrupt these services, leading to economic and health impacts. For example, bee declines threaten crop pollination, costing billions annually.

Biodiversity

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