Chapter 15 - Evolution

Biology

Mr. Hines

15.1 – The Puzzle of Life.Target 1 - Explain Biodiversity.

• A. The puzzle of life’s diversity

• B, The earth is filled with millions of different life forms.

• C. Life on earth is very diverse and includes everything from intelligent beings like humans to single celled organisms known as bacteria.

• D. The variety of living things on earth is called biodiversity.

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• E. With such diversity on the planet, many

questions arise.

• F. How did organisms arise?

• G. How are they related?

• H. Questions like these are known as the “puzzle of life’s diversity.”

• I. We will look into this puzzle in this chapter – according to science.

Target 2 - Explain the basic idea behind a theory.

• A. Remember that science is based on observations.

• B. There is a lot of data which supports the theory of evolution – most scientists believe evolution to be true.

• C. However, the term theory suggests that evolution cannot be confirmed as fact.

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• D. Theory – well supported testable explanation of phenomena that have occurred in the natural world.

• E. Therefore, evolution is a theory.

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Target 3 - Define Evolution and give examples.

• A. Evolution is sometimes misunderstood. • B. Some people think that evolution says that monkeys

turn into humans – Evolution does not say this at all.• C. Evolution is a complex understanding of how

populations of organisms change of long periods of time.

• D. Evolution’s most simple definition is – CHANGE OVER TIME.

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• E. For example, humans were not the same today as they were hundreds of thousands of years ago.

• F. Fossil evidence proves this to be true.• G. Since humans have CHANGED OVER

TIME, it shows that humans have evolved – change over time.

• H. We will look at this in more detail soon•

Target 4 - Give basic facts about Charles

Darwin and his Voyage of the Beagle.• A. Charles Darwin contributed most of our

understanding of Evolution.• B. We will study the work of Darwin in this

chapter – his name will be mentioned many times.• C. Darwin sailed a ship called “The Beagle”

around the world making many observations (1831)

• D. Most of his work was done on the Galapagos Islands – west of South America

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• E. During his travels, he made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes.

• F. In more recent years, his hypothesis has generated enough evidence to become a theory.

• G. Evolution explains every aspect of the puzzle of the diversity of life.

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Target 5 - Understand Darwin’s observations.

• A. Throughout Darwin’s travels, he collected 68 different species of beetles – he wasn’t even looking for beetles.

• B. This led him to realize the amazing patterns and diversity of life.

• C. Darwin was intrigued by the fact that so many plants and animals seemed remarkably well suited to whatever environment they inhabited.

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• E. As he traveled from continent to continent, he noticed that there were no rabbits in Australia – and no kangaroos in England.

• F. Why is this since the habitats in both continents are similar?

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Target 6 - Understand the connection between Living

organisms and fossils.• A. Darwin realized that the living organisms

were just a small part of the puzzle.

• B. As he collected fossils, he realized that most of the puzzle was found in the fossil record.

• C. Many organisms in the fossils were very different from organisms alive today.

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• D. This indicated that many species died off.

• E. This also indicated that life on Earth is different today as it was then.

• F. Many of Darwin’s discoveries were from the Galapagos Islands.

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Target 7 - Describe the diversity of the Galapagos Islands.

• A. Out of all of the continents Darwin visited, he was most influenced by what he saw on the Galapagos Islands – 800 miles west of South America.

• B. Even though the islands were close together, each island had a different climate.

• C. Some islands were hot, dry, and barren with sparse vegetation

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• D. Others had mountains with lots of vegetation and rainfall.

• E. Darwin paid close attention to the giant tortoises and ground finches.

• F. He noticed that the tortoises were different on each island and suited for the environment.

• G. We will take a closer look at the tortoises (big turtles) and finches (birds).

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Target 8 - Compare and Contrast the Tortoises on three different

Galapagos Islands.•

• A. Tortoises on Hood Island

• 1. The vegetation on Hood Island is sparse.

• 2. This tortoise is suited for this environment with a long neck to reach higher vegetation and a shell that allows it to extend its neck.

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• B. Tortoises on Isabela Island

• 1. The vegetation on Isabella is very abundant and closer to the ground.

• 2. The tortoise on this island has a short neck and a shell that does not allow it to extend its neck

• C. Tortoises on Pinta Island

• 1. The tortoise on Pinta island has a neck and shell intermediate to the other 2 – based on its habitat.

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Target 9 - Compare and Contrast the different Finches

on the Galapagos Islands.• A. Now we will take a close look at the

finches – there are 13 species on the Galapagos.B. The finches are all about the same size, but their beaks are all different.

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• C. Each bird has a different kind of beak which is suited for the environment on a specific island.

• D. Some of the finches live on an island where there is lots of vegetation.

• E. The size of the beak depends on the kinds of seeds that are available to them.

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• **Look at figure A and draw a Finch below which will likely be most adapted to eat small seeds.

• **Look at figure A and draw a Finch below which will likely be most adapted to eat large seeds.

• Write a complete sentence about how beak size gives a finch a survival advantage.

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Target 10 - Describe Darwin’s final thoughts as he journeyed

home.• A. As you might imagine, sailing the seas in the

1800s took a long time. • B. Darwin had a lot of time to sit around and think.• C. He started to connect the dots about how living

things were suited for their environment.• D. He wondered if all of the different species on

each of the islands were once members of the same species.

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E. In other words, he wondered if one species arrived on the island, and over time, they changed to adapt to the environment which is different on each island.

•F. Was this possible? Can living things change over time to adapt to new environments?

•G. If so, it would turn peoples’ view of the natural world upside down.

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15.2 - Ideas that shaped Darwin’s thinking.

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Target 11 - Understand some older ideas about the world –

when Darwin lived.• A. Darwin lived in a time when the world

was being explored.

• B. Much of the scientific knowledge that was forming was about the earth and living things.

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• C. Some ideas that were changing.

• 1. The earth is flat

• 2. The earth is unchanged from its creation.

• 3. Life was created thousands of years ago.

• 4. Living things are today as they have always been.

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• D. In other words, science was proving many old ideas to be incorrect.

• E. Science and Religion began to conflict. Consider this for thought.

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• Science = unanswered questions.

• Religion = unquestioned answers.

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• F. As time passes, science answers new

questions based on current observations.

• G. As we learn more, new questions arise.

• H. For example - As fossil evidence was uncovered, humans had to rethink their ideas that living things are today as they have always been - Humans had to change their thinking.

• I. Fossil evidence supports the fact the living things are NOT today as they have always been.

The skull labeled N is a current human skull. If you look at older *human skulls, they are different. Fossil evidence demonstrates that humans have

changed over time.

• human = Homo sapiens. Older skulls not Homo sapiens.

Target 12 - Explain what fossil evidence supports.

• A. Fossil evidence supports the fact that living things are not today as they have always been.

• What does fossil evidence support?

Target 13 - List and explain the two important discoveries made by Hutton and Lyell.

• A. Hutton and Lyell made 2 important discoveries about the earth.

• The earth is millions of years old.

• The earth changes slowly over time.

• B. These changes involved layers of rock pushing up from beneath, forming mountains and valleys (earthquakes and volcanoes) – this is going on right now all over the world (US – California).

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• C. Fossils of ancient sea creatures are found at the top of mountains – How?

• D. Rocks are pushed up from forces beneath the Earth’s crust.

• E. Mountains and valleys are then reshaped by wind, rain, heat, and cold, etc. (erosion)

• F. These changes occur very slowly – hardly noticeable in one’s lifetime.

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• G. The earth is always changing – this study

is called Geology.

• H. Geology – the study of the changing earth.

• I. Geology proved that the Earth is very old – 4.5 billion years old.

• J. Geology showed that Earth is different from its creation.

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Target 14 - Understand the connection between the changing earth and living things on it.

• A. Darwin was influenced by our understanding of geology.

• B. If the earth could change, what about living things.

• C. If living things were to change, it would take lots of time – the earth would have to be very old – it is.

Target 15 - Explain Lamarck’s Evolution Hypothesis.

• A. Before the time of Darwin, a naturalist by the name of Lamarck proposed that by selective use or disuse of organs, animals lose or gain certain traits over the course of their lifetime.

• B. These traits could be passed on to offspring and could change a species over time.

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• C. This is called Tendency towards perfection by use or disuse.

• D. Lamarck claimed that an organism could alter the shape of its body by use or disuse.

• E. Was Larmarck correct?

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• Example 1 – Did giraffes get long necks by stretching towards taller trees ultimately producing offspring with longer necks?

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Target 16 - Define Acquired Trait and explain why it cannot be passed to

offspring.• A. An acquired trait is learned or

developed - is not part of DNA.

• B. Lamarck proposed that offspring could inherit the acquired traits from parents.

• C. This is like saying that a woman who lifts weights (acquired trait) and becomes stronger will pass on “strong genes” to her children.

• D. This is also like saying that a person who speaks “French” will have children who are born with the ability to speak French.

• E. Acquired traits cannot be passed to offspring – not in DNA.

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Target 17 - Evaluate Lamarck’s Hypothesis.

• A. Lamarck was incorrect in many ways –here are two examples.

• 1. Acquired traits are not inheritable.

• 2. Behavior has no effect inheritable traits.

• B. He did however develop the idea that organisms do adapt to their environment.

• C. Lamarck’s hypothesis was proven to be incorrect.

Target 18 - Explain the ideas of Thomas Malthus.

• A. Darwin was also influenced by the work of Economist Thomas Malthus.

• B. Malthus noticed that humans were being born faster than they were dying.

• C. This meant that at some point, humans would run out of food and living space for everyone.

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• D. For many years, war, disease, famine, helped keep this in check.

• E. Darwin applied this idea to plants and animals since they reproduce much more quickly than humans.

• F. A maple tree can produce thousands of seeds in a single summer.

• G. An oyster can produce millions of eggs per year.

• H. If all of the offspring lived, the world

would be over run.

• I. Since the oceans are not filled with oysters and the continents are not covered with maple trees, something is preventing all of the offspring from living.

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• J. What causes some to live and some to die?

• K. Only the ones that live will be able to reproduce.

• L. Is it that the strong survive – and therefore reproduce?

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