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Chapter Menu. Lesson 1: Natural Selection Lesson 2: Adaptation and Extinction. Click on a hyperlink to view the corresponding lesson. 5.1 Natural Selection. evolution naturalist natural selection adaptation. 5.1 Natural Selection. Charles Darwin. Evolution is change over time.

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  1. Chapter Menu Lesson 1:Natural Selection Lesson 2:Adaptation and Extinction Click on a hyperlink to view the corresponding lesson.

  2. 5.1 Natural Selection evolution naturalist natural selection adaptation

  3. 5.1 Natural Selection Charles Darwin • Evolution is change over time. • The naturalist Charles Darwin was the first person to write a thorough collection of evidence supporting evolution. • Darwin’s theory serves as the basis of all biological research today.

  4. 5.1 Natural Selection Charles Darwin (cont.) • Darwin explored South America and its remote islands, such as the Galapagos, on the HMS Beagle.

  5. 5.1 Natural Selection Darwin’s Observations • Darwin made observations about the diversity and uniqueness of organisms. • Many of the animals on the Galapagos were similar, but not the same as organisms in mainland South America. • Darwin reasoned that perhaps the organisms in the Galapagos originally came from South America and over time, they had evolved.

  6. 5.1 Natural Selection Tortoises • Darwin found giant tortoises on all the Galapagos Islands, but nowhere else. • He reasoned that each new population changed slightly, or evolved, to fit its unique environment on the island.

  7. 5.1 Natural Selection Finches • Darwin was impressed by the diversity of finches on the Galapagos. • Darwin explained that if individuals from a species were separated, future generations might look and behave differently. • The finches became different because they became suited to the different habitats on the islands.

  8. 5.1 Natural Selection Selective Breeding • Selective breeding is breeding plants and animals to get offspring with desired characteristics. • This does not lead to a new species—the organism can still breed with other members of its species.

  9. 5.1 Natural Selection Darwin’s Theory of Natural Selection • Organisms with traits that allowed them to survive under particular environmental conditions produced more offspring. • Eventually those traits would be common in the species. How can natural selection be modeled?

  10. 5.1 Natural Selection Genetic Variation • Sometimes changes occur in genes and a new trait is created. • If the trait is beneficial, the organism may survive and pass the trait on to the next generation. • Genetic variation is necessary for evolution to occur.

  11. 5.1 Natural Selection Population Growth and Struggle to Survive • Although resources are limited, animals often produce more offspring than could survive. • Darwin decided this was a natural process that selected which organism survived, and called it natural selection. • Adaptation refers to traits that increase the likelihood of surviving and reproducing in a particular environment.

  12. 5.1 Natural Selection Natural Selection • Four steps or requirements of Darwin’s theory of evolution by natural selection: • Step 1: Overproduction • Step 2: Relative similarity • Step 3: Inherited variation • Step 4: Natural selection

  13. 5.1 Natural Selection Natural Selection (cont.) Overproduction Inherited Variation Variation Natural Selection

  14. 5.1 Natural Selection Lesson 1 Review • A • B • C • D What did Darwin observe about the tortoises and finches in the Galapagos? A their large size B their similarity to those on the mainland C their adaptations to their environments D their friendliness

  15. 5.1 Natural Selection Lesson 1 Review • A • B • C • D What is necessary for evolution to occur? A selective breeding B genetic variation C populations isolated on islands D none of the above

  16. 5.1 Natural Selection Lesson 1 Review • A • B • C • D What is not a main source of genetic variation? A differences in diet B sexual reproduction C mutations D gamete formation

  17. End of Lesson 1

  18. 5.2 Adaptation and Extinction structural adaptation camouflage mimicry behavioral adaptation extinct

  19. 5.2 Adaptation and Extinction Adaptations • Humans can change their environment to meet their needs. • Organisms have evolved adaptations to their environment by the process of natural selection.

  20. 5.2 Adaptation and Extinction Understanding Adaptations • Adaptations are inherited traits that increase an organism’s chance of surviving and reproducing in a particular environment. • Adaptations are the final products of the long process of natural selection. • Adaptations are naturally selected for, not intentional. • Not all traits are adaptations.

  21. 5.2 Adaptation and Extinction Types of Adaptations • Structural adaptations are aspects of the physical body that help organisms survive and reproduce. • Camouflage—coloring that blends with the environment—makes organisms difficult to see.

  22. 5.2 Adaptation and Extinction Types of Adaptations (cont.) • Mimicry is when one species (the mimic) looks like another species (the model) in order to deceive a third species. • Behavioral adaptations are actions or behaviors that help organisms survive and reproduce.

  23. 5.2 Adaptation and Extinction Extinction • A species becomes extinct when all the individuals of a particular species die off. • There have been several major extinction events in history.

  24. 5.2 Adaptation and Extinction Causes of Extinction • Loss of habitat • Loss of genetic diversity • Competition with exotic species • Inability to adapt Causes of Slow Extinction

  25. 5.2 Adaptation and Extinction Lesson 2 Review • A • B • C • D What is not an example of an adaptation? A inbreeding B camouflage C mimicry D behavior

  26. 5.2 Adaptation and Extinction Lesson 2 Review • A • B • C • D Why do some non-desirable traits remain in a population? A selective breeding B mutation C they are genetically linked to more beneficial traits D they may be useful in the future

  27. 5.2 Adaptation and Extinction Lesson 2 Review • A • B • C • D What cause for extinction would most likely be involved in rapid environmental changes such as climate change? A loss of habitat B inability to adapt C loss of genetic diversity D competition with exotic species

  28. End of Lesson 2

  29. Chapter Resources Menu Chapter Assessment California Standards Practice Image Bank Science Online Interactive Table Virtual Lab Click on a hyperlink to view the corresponding feature.

  30. Chapter Assessment 1 • A • B • C • D What is evolution? A adaptations to particular environments B genetic change in a population over time C natural selection D differences in traits

  31. Chapter Assessment 2 • A • B • C • D What is necessary for natural selection to occur? A genetic variation B constant environmental conditions C isolate populations D shortage of offspring

  32. Chapter Assessment 3 • A • B • C • D Which of the following is NOT one of the main sources of genetic variation in a population? A mutations B learned abilities C formation of gametes D sexual reproduction

  33. Chapter Assessment 4 • A • B • C • D Which of the causes of extinction is not influenced by human actions? A inability to adapt B loss of genetic diversity C loss of habitat D competition with exotic species

  34. Chapter Assessment 5 • A • B • C • D Why do desert rabbits have mottled fur? A behavioral adaptations B mimicry C camouflage D incomplete dominance

  35. SCI 3.a CA Standards Practice 1 • A • B • C • D What causes evolution? A genetic variation B environmental factors C both D neither

  36. CA Standards Practice 2 SCI 3.e • A • B • C • D What is one reason exotic species can sometimes outcompete native species? A they have no natural predators B there are more of them C the new environment is more favorable D the natives are not adapted

  37. CA Standards Practice 3 SCI 3.e • A • B • C • D When do we designate a species as threatened or endangered? A when there is one population left B when the number of individuals falls below a certain level C when population numbers are declining D when genetic variation is low

  38. CA Standards Practice 4 SCI 3.a • A • B • C • D Which is required for natural selection to occur? A inherited variation B overproduction of offspring C genetic variation D all of the above

  39. CA Standards Practice 5 SCI 3.b • A • B • C • D Which of the following did not contribute to Darwin’s development of the theory of natural selection? A overproduction of offspring B competition with exotic species in the Galapagos C an essay on human population growth D similarities and differences of species in the Galapagos

  40. Image Bank

  41. Interactive Table Causes of Slow Extinction

  42. End of Resources

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