Thursday, May 28, 2015• HOMEWORK: Finish Initial models of

Red Bellied Snakes (Doc#12)

• OBJECTIVE: I will be able to create models that show the change in a species over time, multiple generations, offspring and final version of a species

• DO NOW: Read the introduction of the Red Bellied Snake packet.

Another surprising change:Snake heads are getting

smaller in Australia!

We can develop evolutionary models to explain this.

This is a Red-Bellied Black Snake. They live in Australia, usually in forests or woodland areas. They are poisonous, but not very poisonous. Their bite is usually not poisonous enough to kill people.

These snakes’ head sizes vary.

The snakes feed on frogs and toads.

These are cane toads, also found in Australia. The toads are poisonous and large in size. They were first introduced to Australia by humans in 1935.

In places where the toads are, the snakes have smaller

heads, on average, than they did in 1935. Why???

Evolutionary Model

In this lesson you will develop an evolutionary model to show why the head size of the Australian Red-Bellied Black Snake has changed in size over the past 75 years.

The EvidenceIn groups, study Evidence 1-6 on the computer. Then, discuss each question you see on the computer and try to reach a consensus. Be sure you listen to everyone’s ideas.

After you understand each piece of evidence, discuss the questions for that evidence on the next slide and in your packet. When you all agree on the best answer, individually circle or write your answer.

We will go over the answers to the multiple-choice questions when you have finished all the evidence.

Evidence 1 & 2: Questions

Evidence 3: Questions

Snakes with big heads were able to eat the cane toads, which poisoned and killed the snakes. Therefore, there were MORE big headed snakes in areas WITHOUT cane toads and there were FEWER big headed snakes in areas WITH cane toads.

Evidence 4 & 5: Questions

Evidence 6: Question

Your Model•Using the evidence, develop a model that shows why the head size of the Australian Red-Bellied Black Snakes has changed since 1935. •Develop your model in the space in your packet on page 4.•Think about what you have learned about evolutionary changes in the mountain sheep and the peppered moths as you develop your model. •Make sure your model can be understood by anyone who reads it. •Look back at the examples of Abstract models to help you develop your model.

Closure

Look over class model criteria. –Does your model fit the model criteria? –Do you think it’s a good model? Explain.

–Initial Models are to be finished for homework if not completed during class.