ch11 evolution section 1
TRANSCRIPT
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Evolution and Change
• Chapter Eleven: Evolution
• Chapter Twelve: Earth and Life History
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Chapter Eleven: Evolution
• 11.1 Evidence for Evolution
• 11.2 How Evolution Works
• 11.3 Natural Selection
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11.1 Evidence for Evolution• An adaptation is an inherited trait that helps an
organism survive.• Adaptations include body structures that help an
organism feed, move around, and protect itself.
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11.1 Evidence for Evolution
• Evolution is the process of how organisms acquire adaptations over time.
Eohippus is an ancestor of what modern animal?
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11.1 Evolution is a branching process• Diversity means variety.• Scientists hypothesize that all life forms evolved
from a common ancestor and new species branch off from earlier species.
• Similarities among all cells support the hypothesis that all life evolved from a common ancestor.– All cells have a similar cell membrane. – Many cells have the same type of cellular respiration. – All cells have DNA as their hereditary material.
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11.1 Evolution is a branching process• An ancestor is an
organism from which others have descended.
• A cladogram displays evolutionary relationships among living species and their ancestors.
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11.1 Lines of Evidence• Many lines of evidence
provide the basis for the theory of evolution. These include:– comparative anatomy– DNA analysis– fossil record
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11.1 Lines of Evidence• Comparative anatomy is the study of
anatomical similarities and differences among species.
• What does your arm have in common with the wing of a bird, the flipper of a porpoise, and the forelimb of an elephant?
• Analogous structures serve the same function but come from different origins.
• Homologous structures have a common origin, but do not necessarily perform the same function.
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11.1 Lines of Evidence• Vertebrates are animals
with a backbone.• Comparative anatomists
have discovered similarities in embryos of vertebrates.
• Adult vertebrates also share many similarities in their skeletons and muscles.
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11.1 Lines of Evidence• Species that share more similarities in their
DNA base sequences are more closely related than those that share fewer similarities.
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11.1 Fossils• A fossil is a remnant or trace of an
organism from the past, such as a skeleton or leaf imprint, embedded and preserved in Earth’s crust.
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11.1 Fossil Record• Fossils found in the upper (newer)
sedimentary layers more closely resemble present-day organisms than fossils found in deeper (older) layers.
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Ecology Connection
• All animals try to blend into their surroundings. Some are nearly perfect at it.
Chameleon of the Sea