Natural selection

• Disruptive selection is a type of natural selection that favors individuals with extreme traits at both ends of the spectrum, leading to the formation of two distinct phenotypes.
• Natural selection can lead to adaptations through genetic drift, mutation, gene flow, and sexual selection.
• Darwin's finches on the Galapagos Islands are an example of how different species can evolve over time due to natural selection.
• The theory of natural selection was proposed by Charles Darwin, who observed that populations of animals and plants vary from one another and some individuals have traits that make them better suited to their environments.
• Natural Selection is the process by which organisms better adapted to their environment tend to survive and reproduce more than those less well-adapted.
• Sexual selection is a type of natural selection that favors individuals with traits that increase their chances of mating and reproducing, even if those traits may be disadvantageous in other aspects of survival.
• Genetic drift refers to changes in allele frequencies due to chance events during reproduction or migration.
• Gene flow occurs when genes are exchanged between different populations, either by immigration/emigration or hybridization.
• The peppered moth experiment demonstrated how natural selection can cause changes in populations over time.
• Who proposed the theory of evolution by natural selection?

  Charles Darwin and Alfred Russel Wallace.
• What is Darwin and Wallace’s theory of evolution?

  All species evolve over time due to natural selection — organisms with the most beneficial traits survive and reproduce
• What is evolution by natural selection?

  A process where individuals with advantageous traits are more likely to survive, reproduce, and pass on their genes.
• What is emerging resistance?

  When bacteria evolve to become resistant to antibiotics due to natural selection.
• Give an example of emerging resistance.

  MRSA (a bacterium resistant to many antibiotics).
• How do fossils provide evidence for human evolution?

  Fossils show gradual changes in skull size, posture, and tool use over time in early humans (e.g. Ardi → Lucy → Homo habilis → Homo erectus → Homo sapiens).
• What is a limitation of using fossils for evidence?

  The fossil record is incomplete — not all organisms fossilise and survive.
• How are stone tools dated?

  By the rock layers they are found in (stratigraphy) or using carbon dating of surrounding material.
• What does tool complexity tell us about human evolution?

  Tools became more advanced over time, showing increased brain size and problem-solving abilities in early humans.
• What is anatomical evidence for evolution?

  Similar body structures (like limb bones) in different species suggest common ancestry (homologous structures).
• Example of anatomical evidence for evolution?

  Pentadactyl limb is found in humans, whales, bats, and birds - shows a common ancestor between the animals