Flashcards · Biology · Evolution and Natural Selection
Natural Selection
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What is natural selection?
The process by which better adapted individuals survive and reproduce, passing on their alleles.
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What are the five steps of natural selection?
Variation, competition, survival of the best adapted, reproduction, and change in the population.
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Why do organisms compete?
More offspring are born than the environment can support.
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What does survival of the fittest mean?
The individuals best suited to the environment survive and breed.
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What is an adaptation?
A feature that helps an organism to survive in its environment.
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Name three types of adaptation.
Structural, behavioural and functional.
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Why are adaptations passed on?
They are controlled by alleles.
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What happened to the peppered moths during the Industrial Revolution?
The dark form became more common, because it was camouflaged on sooty trees.
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Why did the pale form become common again after 1956?
The air was cleaner, the trees became paler and dark moths were seen more easily.
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What was Lamarck's idea?
That characteristics acquired during life are inherited.
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Why is Lamarck's idea wrong?
Acquired characteristics do not change the genes in the gametes.
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What is speciation?
The formation of a new species.
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How can a new species form?
A population is isolated, different selection acts on each group, and they can no longer interbreed.
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What does the proportion of an allele do over many generations if it is advantageous?
It increases.
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Does natural selection happen in an individual during its lifetime?
No. It acts on a population over generations.
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Common mistake about natural selection?
Saying that organisms change because they need to. Variation is already there, and selection acts on it.