 Catalyst:  When you hear the word mutation, what do you think of? Write at least three complete sentences. Write in complete sentences! Don’t talk during the Catalyst! Mutation and Natural Selection

Objectives By the end of today, all SWBAT…  Define “mutation”  Identify environmental pressures  Describe how natural selection determines whether organisms live or die

Agenda  Catalyst Review  What Is a Mutation?  Environmental Pressure and Natural Selection Notes  Online Demo  Quick Guided Practice  Lab  Exit Questions

What is a mutation?  Key Point #1: A mutation is a change in DNA sequence  Fitness = ability to survive and produce offspring  Mutations can increase fitness, decrease fitness, or not matter  Mutations are caused by…  Mistake during transcription or meiosis  Radiation  Chemicals  Gene therapy

Mutations Cause Variation DNA RNA Protein (Trait) a change here… means a change here and here and finally here

Mutations Cause Variation  Mutations cause variation  Variation = changes or differences

 Key Point #2: Environmental pressures cause some organisms to survive better than others.  Examples:  In the grassland, lions must compete against each other to catch gazelle (their food). What is the environmental pressure? What kind of lions would survive best? Environmental Pressure  In the tundra, polar bears live in the snow. If they can be seen easily, their prey will run away and they will starve. What is the environmental pressure? What kind of polar bears would survive best?

Natural Selection  Key Point #2: Natural selection is survival of the fittest.  Mutations that increase fitness become more common. Because organisms that fit well in their environment live longer, and produce more offspring.  Mutations that decrease fitness become less common. Because organisms that do not fit well in their environment die sooner, and produce fewer offspring.

Environmental Pressure Demo  AWESOME NATURAL SELECTION DEMO AWESOME NATURAL SELECTION DEMO

Guided Practice 1  Long ago, some four-legged organisms lived in the desert. Some had more eyelashes than others. Their eyelashes helped to keep sand out of their eyes, so they could find food more easily.  What caused some organisms to have more eyelashes?  What is the environmental pressure?  What happened to the organisms with many eyelashes? Why?  What happened to the organisms with few eyelashes? Why?

Guided Practice 2  Thousands of years ago, primitive four-legged reptiles lived in the Louisiana swamps. They ate wildebeest, but there weren’t enough wildebeest around for everyone. Some reptiles had stronger jaw muscles than others.  What caused reptiles to have different strength jaws?  What is the environmental pressure?  What happened to the reptiles with stronger jaws? Why?  What happened to the reptiles with weaker jaws? Why?

Guided Practice 3  Deer are hunted by coyotes. In a population of deer, some are faster than others.  What caused variation in how fast the deer run?  What is the environmental pressure?  What happened to the faster deer? Why?  What happened to the slower deer? Why?

Lab: Skittles!  You have five minutes to…  Fill in the hypothesis and dependent variable  Read the procedure  Answer the pre-lab questions

Key Point Wrap-Up  Key Point #1: A mutation is a change in DNA sequence  Key Point #2: Environmental pressures cause some organisms to survive better than others.  Key Point #3: Natural selection is survival of the fittest.

Exit Questions  In the tropical jungle, some monkeys have longer arms than others. The longer-armed monkeys are more successful at climbing trees for food than the shorter-armed monkeys.  What caused the variation in monkeys’ arm length?  What is the environmental pressure?  What will happen to the shorted-armed monkeys? Why?  What will happen to the longer-armed monkeys? Why? Write in complete sentences! Don’t talk during the Exit Question!