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How natural selection drives biological evolution

Key ideas • Key ideas

Key concepts

What you'll likely be quizzed about

  • Natural selection describes the process by which individuals with traits that enhance survival or reproductive success become more common in a population over generations.
  • Variation within a population drives this process, leading to individuals with beneficial traits reproducing more frequently, thus increasing the frequency of their alleles.
  • Charles Darwin summarized this as a recurring 'struggle for existence' that favors advantageous variations.

Flashcards

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What evidence supports evolution by natural selection?

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Evidence includes observed antibiotic resistance, fossil sequences, comparative anatomy, and genetic mapping showing relatedness and inherited changes over time.

Key notes

Important points to keep in mind

Variation must be heritable for natural selection to change a population.

Selection pressure causes differential survival and reproduction.

Mutations introduce new alleles; recombination reshuffles existing alleles.

Small changes in allele frequency accumulate over generations.

Reproductive isolation prevents gene flow and enables speciation.

Competition and environmental change commonly drive selection.

Artificial selection illustrates the mechanism of natural selection.

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