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Natural selection and evolution explained

Inheritance, variation and evolution • Variation and evolution

Key concepts

What you'll likely be quizzed about

  • Evolution is a change in the inherited characteristics of a population over time.
  • Changes occur across generations when allele frequencies shift within the population, leading to different phenotypes.
  • Evidence for evolution includes fossil records, observed changes in modern populations, and genetic mapping linking traits across species.
  • Key limiting factors include the timescale required for changes and the necessity of heritable genetic changes.

Flashcards

Test your knowledge with interactive flashcards

Antibiotic resistance - demonstration

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Antibiotic use eliminates susceptible bacteria; resistant variants survive and reproduce, increasing resistance in the population.

Key notes

Important points to keep in mind

Evolution describes population change over generations, not individual change.

Natural selection requires variation, heritability, and differential reproductive success.

Advantageous traits increase because better survival leads to more descendants with those traits.

Mutation provides genetic variation; most mutations are neutral or harmful, few are beneficial.

Geographic isolation facilitates speciation by preventing gene flow and allowing independent selection.

Artificial selection can decrease genetic diversity compared to natural selection.

Examples of rapid evolution include antibiotic resistance and invasive species effects.

Genetic drift in small populations may alter allele frequencies independently of selection.

Co-evolution leads to reciprocal adaptations between species, potentially causing rapid changes.

Evidence for evolution includes fossils, modern observational data, comparative anatomy, and genetics.

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