Catalyst: Depends on Cline’s lesson

Natural Selection and Adaptation

Write in complete sentences!

Don’t talk during the Catalyst!

Objectives

By the end of today, all SWBAT…

Identify environmental pressures

Describe how natural selection produces adaptations

Key Point #1: 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. Organisms that fit well in their environment

live longer, and produce many offspring. Organisms that do not fit well in their

environment die sooner, and produce few offspring.

Environmental Pressure Demo AWESOME NATURAL SELECTION DEMO

Adaptations

Key Point #3: Over thousands of years, natural selection produces adaptations. Eventually, the only organisms left will be

the ones that are well-suited to their environment!

We call the features that help these organisms survive adaptationsAdaptation: a heritable trait that helps an organism survive in its specific environment

Structural Adaptation

Bird Wing

Moth Coloring

Physiological Adaptations

Secreting Slime

Making venomBioluminescence

Behavioral Adaptations

Migration is a voluntary behavior

Goosebumps is a reflex behavior

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 is the environmental pressure? What happened to the organisms with many

eyelashes? Why?

What happened to the organisms with few eyelashes? Why?

Over a period of thousands of years, how did the organisms adapt to their situation?

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 is the environmental pressure? What happened to the reptiles with stronger jaws?

Why? What happened to the reptiles with weaker jaws?

Why? Over a period of thousands of years, how did the

reptiles adapt to their situation?

Guided Practice 3

Deer are hunted by coyotes. In a population of deer, some are faster than others. What is the environmental pressure? What happened to the faster deer?

Why? What happened to the slower deer?

Why? Over a period of thousands of years, how

will the deer adapt to their situation?

Lab: Quackers!

You have five minutes to… Fill in the hypothesis and dependent variable

Read the procedure Answer the pre-lab questions

Watch as I demonstrate the first round of the lab

Key Point Wrap-Up

Key Point #1: Environmental pressures cause some organisms to survive better than others.

Key Point #2: Natural selection is survival of the fittest.

Key Point #3: Over thousands of years, natural selection produces adaptations.

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 is the environmental pressure? What will happen to the shorted-armed

monkeys? Why?

What will happen to the longer-armed monkeys? Why?

Over a period of thousands of years, how will the monkeys adapt to their situation?

Write in complete sentences!

Don’t talk during the Exit Question!