Evolution

• Over time, beneficial characteristics become more common in the population and the species
• Charles Darwin's theory of evolution by natural selection

  Organisms with the most suitable characteristics for the environment are more likely to survive and reproduce
• In a species, organisms show wide variation in their characteristics (phenotypes)
• Only the Fittest Survive
• New discoveries have helped to develop the theory of evolution
• Speciation happens when populations of the same species change enough to become reproductively isolated, meaning they can't interbreed to produce fertile offspring
• All of today's species have evolved from simple life forms that started to develop over three billion years ago
• The recent discovery of how bacteria evolve to become resistant to antibiotics further supports evolution by natural selection
• Dodos are now extinct due to hunting, introduction of other animals, destruction of their eggs, and habitat loss
• Looking at fossils of different ages (the fossil record) shows how changes in organisms developed slowly over time
• Organisms have to compete for limited resources in an ecosystem
• Charles Darwin came up with a really important theory about evolution called evolution by natural selection
• The discovery of genetics supported Darwin's idea by explaining how organisms pass on beneficial characteristics via their genes
• The development of a new species is called Speciation
• Extinction is when no individuals of a species remain
• Reasons for species becoming extinct

  • The environment changes too quickly (e.g. destruction of habitat)
  • Predators kill them all (e.g. humans hunting them)
  • They can't compete with another species for food
  • Natural disasters (e.g. volcanic eruption or collision with an asteroid)