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Chapter 7 Bellringer The cockroach first appeared on
Section 1 Change over Time Bellringer The cockroach first appeared on Earth over 250 million years ago and is thriving today all over the world. A giant deer that was 2 m tall and had antlers up to 3.6 m wide first appeared less than 1 million years ago and became extinct around 11,000 years ago. Why do you think one animal thrived and the other one perished? Record your answer in your science notebook. Header – dark yellow 24 points Arial Bold Body text – white 20 points Arial Bold, dark yellow highlights Bullets – dark yellow Copyright – white 12 points Arial Size: Height: 7.52" Width: 10.02" Scale: 70% Position on slide: Horizontal - 0" Vertical - 0"
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Chapter 7 Section 1 Change over Time Objectives Identify two kinds of evidence that show that organisms have evolved. Describe one pathway through which a modern whale could have evolved from an ancient mammal. Explain how comparing organisms can provide evidence that they have ancestors in common.
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Chapter 7 Differences Among Organisms
Section 1 Change over Time Differences Among Organisms What Is a Species? A species is a group of organisms that can mate with one another to produce fertile offspring. A characteristic that helps an organism survive and reproduce in its environment is called an adaptation.
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Differences Among Organisms, continued
Chapter 7 Section 1 Change over Time Differences Among Organisms, continued Do Species Change over Time? Scientists observe that species have changed over time. The slow process in which populations gradually change over time is called evolution.
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Chapter 7 Evolution Section 1 Change over Time
Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. (60010 video) Visual Concept
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Evidence of Change over Time
Chapter 7 Section 1 Change over Time Evidence of Change over Time Sometimes, the remains or imprints of once-living organisms are found in the layers of rock. These remains are called fossils.
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Evidence of Change over Time
Chapter 7 Section 1 Change over Time Evidence of Change over Time The Fossil Record By studying fossils, scientists have made a timeline of life that is known as the fossil record. The fossil record organizes fossils by their estimated ages and physical similarities.
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Chapter 7 Evidence of Ancestry
Section 1 Change over Time Evidence of Ancestry Order of Life The fossil record provides evidence about the order in which species have existed. Drawing Connections Scientists have named and described hundreds of thousands of living and ancient species. Scientists use information about these species to sketch out a “ tree of life” that includes all known organisms.
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Chapter 7 Examining Organisms
Section 1 Change over Time Examining Organisms Case Study: Evolution of the Whale Scientists think that the ancient ancestor of whales was probably a mammal that lived on land and that could run on four legs. Walking Whales The organisms shown on the next slide form a sequence between ancient four-legged mammals and modern whales. Several pieces of evidence indicate that these species are related by ancestry.
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Chapter 7 Section 1 Change over Time
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Chapter 7 Section 1 Change over Time
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Chapter 7 Comparing Organisms
Section 1 Change over Time Comparing Organisms Comparing Skeletal Structures The structure and order of bones of a human arm are similar to those of the front limbs of a cat, a dolphin, and a bat. These similarities suggest that cats, dolphins, bats, and humans had a common ancestor. (next slide)
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Chapter 7 Section 1 Change over Time
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Comparing Organisms, continued
Chapter 7 Section 1 Change over Time Comparing Organisms, continued Comparing DNA Scientists find that species that have many traits in common do have similarities in their DNA. The fact that all existing species have DNA supports the theory that all species share a common ancestor.
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Chapter 7 Section 7.1 Summary
Section 1 Change over Time Section 7.1 Summary Evolution is the process in which inherited characteristics within a population change over generations, sometimes giving rise to new species. Scientists continue to develop theories to explain how evolution happens. Evidence that organisms evolve can be found by comparing living organisms to each other and to the fossil record. Such comparisons provide evidence of common ancestry.
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Chapter 7 Section 7.1 Summary
Section 1 Change over Time Section 7.1 Summary Scientist think that modern whales evolved from an ancient, land dwelling mammal ancestor. Fossil organisms that support this hypothesis have been found. Evidence of common ancestry among living organisms is provided by comparing DNA and inherited traits. Species that have a common ancestor will have traits and DNA that are more similar to each other than to those of distantly related species.
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Chapter 7 Charles Darwin
Section 2 How Does Evolution Happen? Chapter 7 Charles Darwin Darwin’s Finches Darwin noticed that the finches of the Galápagos Islands were a little different from the finches in Ecuador. And the finches on each island differed from the finches on the other islands.
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Chapter 7 Section 2 How Does Evolution Happen?
Copyright © by Holt, Rinehart and Winston. All rights reserved.
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Changes in Populations, continued
Section 3 Natural Selection in Action Chapter 7 Changes in Populations, continued
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Section 3 Natural Selection in Action
Chapter 7
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Chapter 7 Section 1 Change over Time
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Section 2 How Does Evolution Happen?
Chapter 7
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Chapter 7 Section 3 Natural Selection in Action
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Chapter 7 Section 3 Natural Selection in Action
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Chapter 7 Standardized Test Preparation
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