Natural Selection

• How does evolution take place?

  Through natural selection
• How many different species of animals and plants are estimated to exist on Earth?

  Nearly 9 million
• What percentage of species that have ever lived on Earth are currently extinct?


  99% of the total species
• How long ago did life first develop on Earth?


  More than 3 billion years ago
• What were the first life-forms on Earth?

  Very simple, single-celled organisms
• What is the process called through which all species of living things have evolved?

  Evolution by natural selection
• What is the significance of genetic variation within a population?


  • It allows for different traits among individuals
  • It contributes to the process of natural selection
  • It enhances the adaptability of the population
• In the example of rabbits, what trait gives them a survival advantage in colder temperatures?


  Thicker fur
• What happens to the alleles for thicker fur over many generations in the rabbit population?


  They become more common
• What advantage do rabbits with better eyesight or hearing have when a predator, like a fox, moves into their area?


  They are more likely to detect the predator
• What is the definition of evolution as described in the video?


  The change in inherited characteristics of a population over time through natural selection
• What occurs when two populations of one species become so different that they can no longer interbreed?


  They become two separate species
• What is an example of two different species of rabbits mentioned in the video?

  Normal-sized rabbits and pygmy rabbits
• What is speciation?


  • The process by which new species arise
  • Occurs when populations diverge significantly
  • Results in populations that can no longer interbreed