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All 16 Flashcards — Measuring biodiversity
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Question
What does species diversity measure?
Answer
Species diversity measures both species richness (how many species) and evenness (how evenly individuals are distributed).
💡 Hint
Richness + evenness.
Question
What does Simpson’s Reciprocal Index (D) represent?
Answer
It converts biodiversity into a single value that increases when both richness and evenness increase.
💡 Hint
One number for diversity.
Question
A pond has 10 frogs, 10 fish, and 10 snails. What is N?
Answer
N = 30 individuals in total.
💡 Hint
Add all individuals.
Question
Why does measuring biodiversity help conservationists prioritise action?
Answer
It identifies which habitats or populations are most threatened by comparing diversity and tracking changes over time.
💡 Hint
Compare + prioritise.
Question
What does Simpson’s Reciprocal Index (D) combine into one value?
Answer
It combines richness (number of species) and evenness (how balanced the individuals are).
💡 Hint
Richness + evenness.
Question
Define species richness.
Answer
Species richness is the number of different species present in an area.
💡 Hint
Count species types.
Question
How can biodiversity measurements evaluate conservation success?
Answer
If diversity increases or stabilises after an intervention, it suggests management is helping; if it declines, strategies may need change.
💡 Hint
Track change after action.
Question
In Simpson’s Reciprocal Index, what is N?
Answer
N is the total number of individuals of all species combined in the sample.
💡 Hint
Total individuals.
Question
Define species evenness.
Answer
Species evenness is how evenly individuals are shared among the different species in a community.
💡 Hint
Balance of individuals.
Question
In Simpson’s Reciprocal Index, what is n?
Answer
n is the number of individuals of a single species in the sample.
💡 Hint
Individuals in one species.
Question
Why is “objective comparison” important when comparing habitats?
Answer
It reduces bias by using the same metric (for example D) so different habitats can be compared fairly.
💡 Hint
Same method for both sites.
Question
Give one reason biodiversity can change over time in a habitat.
Answer
Changes in disturbance or human impacts (for example pollution, land use change, invasive species) can alter richness and evenness over time.
💡 Hint
Disturbance changes communities.
Question
What happens to D when one species dominates the sample?
Answer
D decreases because evenness is low and the sum of n(n-1) becomes large for the dominant species.
💡 Hint
Dominance lowers D.
Question
Why can an ecosystem have high richness but low diversity?
Answer
If one species dominates most individuals, evenness is low, so overall diversity is still low despite multiple species being present.
💡 Hint
Dominance lowers evenness.
Question
Give one reason measuring biodiversity is useful.
Answer
It allows objective comparison between habitats and monitoring of change over time to evaluate threats or conservation success.
💡 Hint
Compare + track change.
Question
What does a higher D value mean (Simpson’s Reciprocal Index)?
Answer
A higher D means higher biodiversity, typically due to higher richness and/or more even distribution of individuals.
💡 Hint
Higher D = more diverse.
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Biodiversity
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