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3.1 Biodiversity and evolutionIB Environmental Systems and Societies HL: Flashcards

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Name the three levels of biodiversity.

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Name the three levels of biodiversity.
Genetic diversity, species diversity and habitat (ecosystem) diversity.
Why are genetically uniform populations such as cheetahs vulnerable?
Few resistance alleles are present, so a new disease or change in conditions can affect nearly all individuals.
What are the four requirements for natural selection?
Variation, overproduction of offspring, competition for limited resources, and differences in adaptation affecting survival and reproduction.
Define speciation.
The generation of new species through evolution.
Write Simpson's reciprocal index.
D = N(N − 1) / Σn(n − 1).
Why can sites with equal richness have different Simpson's indices?
The index also depends on evenness; a site dominated by one species has a low index.
[HL] What is the original source of new alleles?
Mutation.
[HL] How does sexual reproduction increase genetic diversity?
Meiosis and random fertilisation combine existing alleles from two parents in new combinations.
[HL] How can reproductive isolation be achieved?
By geographical separation, or for populations in the same area by ecological or behavioural differences.
[HL] What is a biodiversity hotspot?
An area containing a particularly large proportion of species, especially rare and endangered ones; biodiversity is spread unevenly.
[HL] Give an example of human activity changing selective forces.
Poaching in Gorongosa favoured tuskless female elephants, raising their proportion among survivors.
[HL] Why does artificial selection reduce resilience?
Only individuals with chosen traits breed, so genetic diversity falls and fewer resistance alleles remain.
[HL] How old is Earth, and how are epochs defined?
About 4.5 billion years; epochs are defined according to the fossil record.
[HL] What follows a mass extinction?
Rapid speciation, because vacant niches become available.
[HL] What is the Anthropocene?
A proposed geological epoch of rapid environmental change and species extinction due to human activity, with planetary effects detectable in the geological record.

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).