1. Natural Selection SURVIVAL OF THE FITTEST!

2. Natural Selection (from Charles Darwin)  Three main parts:  1. Nature produces variation.  2. Life is a challenge.  3. Organisms in a population compete. ONLY THE STRONGEST SURVIVE! SURVIVAL OF THE FITTEST!

3. Two More Definitions…  Selective Pressure: Environmental pressures on a population.  Biological Evolution: Process of change that results from natural selection.

4. Review Population Change  What will happen with Larkey populations in a new environment?  Will all the Larkeys survive?  Will the Larkeys maintain the same level of variation in their population?  Will the population change in response to the change in the environment?

5. Analyze the Data  1. What features of Larkeys affected their survival?  2. What traits helped Larkeys survive when they moved to the prairie environment?  3. What traits helped Larkeys survive when they moved to the forest environment?  4. What factor in the environment affected the survival of Larkeys?  5. What effect did predation have on the population?  6. What caused the change in the population?  7. How does removing certain individuals from the population increase the number of individuals with other traits?

6. Selective Pressure  8. The coyotes in the prairie put pressure on the prairie Larkey population. The bobcats in the forest put pressure on the forest Larkey population. How did this pressure change the Larkey population?  9. Which traits were adaptations that helped prairie Larkeys survive the pressure?  10. Which traits were adaptations that helped forest Larkeys survive the pressure?

7. Connect to Walkingsticks  1. What selective pressure was brought on the population of walkingsticks?  2. In what way did the population change over time?  3. In what ways are the populations of Larkeys and walkingsticks similar?  4. When a trait disappears from a population, is it gone for good, or can it come back? Explain…