Transcript Evolution
Evolution Biology Evolution is change over time THEORY: best explanation science has to offer about where different organisms came from This theory changes as new scientific information becomes available Charles Darwin Father of modern evolution theory Formed his theory after traveling around the world on the Beagle Important stop: Galapagos Islands Collected various plants and animals Observed behaviors Drew sketches Finches (type of bird) 13 species of finches Many are born but do not survive Found on different islands Beak size and shape varied Ate different food Darwin’s observations: 1. Variation: differences between members of the same species Variation is important to survival! Variety in a species makes it easier to survive especially when change occurs What causes variation? Random Mutations Beneficial Harmful Silent Darwin’s Observations 2. Overproduction of Offspring When organisms reproduce they have more offspring then can actually survive Darwin’s Observations 3. Competition This leads to competition (Survival of the Fittest) Darwin’s Observations 4. Natural Selection Organisms with traits well suited to the environment survive and reproduce at a greater rate You have the genes to be successful in your environment or you don’t Over time, population will be more like those that reproduce An adaptation is a beneficial mutation that makes it possible for an organism to live in a particular place and in a particular way and reproduce. • Physical (like the size, shape or color) Physiological- the way in which its body works Behavioral- how the organism acts • • Name 3 adaptations for each organism shown. Think about where they live, what they eat, what eats them… http://ww w.youtub e.com/w atch?v= Pwymtmj 3ouU http://video.nationalgeographic.com/video/k ids/animals-pets-kids/reptileskids/chameleon-babies-kids/ Natural Selection: An Example In the U.S., people have used shampoos with particular chemicals in order to kill lice We have a lot of lice that are resistant to the chemicals in those shampoos. (Resistant means unaffected) Hypothesis A: Exposure to lice shampoo caused mutations in the lice. Some lice became resistance to the shampoo. Hypothesis B: When the lice were exposed to the shampoo, the non-resistant lice died a sudsy death. The lice who were able to survive the shampoo survived and reproduced. They did not mutate. Which of these hypotheses is correct? Hypothesis B Why? Variation is there already Shampoo killed the less fit (non-resistant) lice More fit (resistant) lice live and reproduce to make more fit (resistant) lice MUTATION ARE NOT CAUSED! DARWIN Darwin called these mutations or changes ADAPTATIONS