Natural selection

• What should you be able to describe by the end of the video?

  What's meant by evolution
• How does evolution take place according to the video?

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

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

  One percent
• How long ago did life first develop on Earth?

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

  Very simple, such as single cells
• What is the process called where all species of living things have evolved from simple life forms?

  Evolution by natural selection
• What is a good example of genetic variation mentioned in the video?

  Rabbits
• How do rabbits demonstrate genetic variation?

  They have different combinations of alleles
• What advantage do rabbits with alleles for thicker fur have in colder environments?

  They are more likely to survive
• What happens to the alleles for thicker fur over many generations in rabbits?

  They become more common in the population
• What happens when a predator, like a fox, moves into the area?

  Rabbits with better eyesight or hearing survive
• What is the result of rabbits with better eyesight or hearing surviving and reproducing?

  Alleles for better eyesight or hearing spread
• What is the definition of evolution provided in the video?

  Change in inherited characteristics over time
• What can happen when two populations of one species become very different?

  They can no longer interbreed
• What is an example of two separate species mentioned in the video?

  Normal-sized rabbits and pygmy rabbits
• Why can't pygmy rabbits breed successfully with normal-sized rabbits?

  They are too different in phenotype
• What will be covered in more detail in a later video?

  Speciation
• Where can you find questions on evolution by natural selection?

  In the vision world book