Evolution by Natural Selection

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

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

  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 species
• 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
• How does a colder environment affect rabbits with thicker fur?

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

  They become more common in the population
• What advantage do rabbits with better eyesight or hearing have when a predator moves in?

  They can detect the predator more easily
• What is the definition of evolution provided in the video?

  Change in inherited characteristics over time
• What occurs when two populations of one species become so different that they can no longer interbreed?

  They become two separate species
• Why can't pygmy rabbits breed successfully with normal-sized rabbits?

  They are too small to interbreed
• What are the key points of natural selection as described in the video?

  • Genetic variation exists within a population
  • Environmental changes favor certain traits
  • Individuals with advantageous traits survive and reproduce
  • Beneficial traits are passed to offspring
  • Over generations, these traits become more common
• What are the implications of speciation as discussed in the video?

  • Two populations can evolve into separate species
  • They may no longer interbreed successfully
  • Genetic differences accumulate over time
  • Environmental pressures can drive speciation