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Define evolution.
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All Flashcards in Topic 3.2
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3.2.110 cards
Define evolution.
Evolution is the gradual change in inherited traits in populations over generations.
Inherited traits change over generations.
Why can rapid environmental change cause extinction?
If change happens faster than populations can adapt through natural selection, survival and reproduction drop and the species may die out.
Too fast to adapt.
What is natural selection?
Natural selection is the process where individuals with advantageous traits are more likely to survive and reproduce, making those traits more common over time.
Traits that help survival spread.
Define speciation.
Speciation is the formation of a new species when populations become reproductively isolated and diverge genetically over time.
Isolation → divergence → new species.
List the four steps of natural selection (in order).
Genetic variation, survival advantage, reproduction, inheritance.
Variation → survival → reproduction → inheritance.
What does “reproductive isolation” mean?
Reproductive isolation means two populations can no longer interbreed to produce fertile offspring.
Can’t successfully breed.
Give a simple sequence for how isolation can lead to speciation.
A population becomes isolated, experiences different selection pressures, accumulates genetic differences, and eventually becomes reproductively isolated from the original population.
Separated → different selection → new species.
In natural selection, why is variation essential?
Because without genetic variation, all individuals respond the same way to a change, so selection cannot favour one trait over another.
No variation = nothing to select.
How does evolution increase biodiversity?
Evolution can produce new species over time (speciation), increasing species diversity and contributing to overall biodiversity.
Evolution → speciation → more species.
Exam link: how can you connect evolution to ecosystem resilience?
Evolution generates biodiversity (more species and traits), which increases redundancy and makes ecosystems more resilient to disturbance.
Evolution → biodiversity → resilience.
Topic 3.2 study notes
Full notes & explanations for Natural selection, variation and speciation
ESS exam skills
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