Evidence for evolution. Grades 9-10

Transcription

1 Grades 9-10

2 Teacher s Guide Teacher s Guide Introduction Thank you for using one of the Honolulu Zoo Society s educational worksheets. This teacher s guide is meant to help you direct your students through the Evidence for Evolution worksheet if needed. The worksheet is designed for students in grade 9-10, and addresses the following grade 9-12 State Science Standards: Unity and Diversity Explain and justify the scientific classification system. Biological Evolution Explain how molecular and anatomical evidences substantiate the theory of evolution. Explain the basic idea of biological evolution. In keeping with current research on worksheets and free choice learning, the tasks on this worksheet mainly require observations of the animals and their behavior, but also some labelreading. The worksheet is a work in progress, though, and any suggestions or insights you have are very welcome! The following map of the Zoo will help you guide your students to the starting point for their worksheet tasks at the nēnē exhibit. 2

3 Teacher s Guide Glossary ANCESTOR: An individual from whom a person or an animal is descended, a forefather. AQUATIC: Growing or living in water. CHARACTERISTIC: A distinguishing trait, quality, or property. EVOLUTION: The historical development of a biological group (species). A theory that the various types of animals (or other organisms) have their origin in preexisting types of animals (or other organisms) and that the distinguishable differences are due to modifications in successive generations. EVOLUTION, CONVERGENT: When the process of evolution causes two unrelated species to become more similar with regard to certain characteristics. EVOLUTION, DIVERGENT: When the process of evolution causes two related species to become more dissimilar with regard to certain characteristics. GENERATION: A group of animals that constitute a single step in the line of descent from an ancestor. MIGRATION: To move from one region or climate to another for breeding or feeding. OFFSPRING: The young of an animal, children. PRIMITIVE: At an early stage of development, an ancestral type. REPRODUCTIVE AGE: Sexually mature age, at an age where individual is able to reproduce or breed. SELECTION: A process that results in the survival and reproduction of some individuals but not of others. This has the result that the inherited characteristics of the survivors are perpetuated. SELECTION, ARTIFICIAL: Human intervention in animal or plant reproduction to ensure that certain desirable traits are represented in successive generations. SELECTION, NATURAL: According to Darwin's theory of evolution, a natural process in which only the organisms best adapted to their environment tend to survive and transmit their genetic characteristics in increasing numbers to succeeding generations while those less adapted tend to be eliminated. TERRESTRIAL: Growing or living on land. 3

4 Teacher s Guide Answer key 1. Which characteristics might these rat-catching dogs have had, in your opinion? Answer: they were probably quick, aggressive, and small. 2. If the rat-catching dogs had the characteristics (speed, size, and temper) that you checked off above, what would the consequences for their offspring be? Answer: The offspring would probably inherit those same characteristics The offspring would probably be good rat-catchers Humans might have taken extra care of the offspring because of their usefulness 3. What s the difference between artificial selection and natural selection? Below, you ll find two scenarios. Indicate which one is natural selection, and which one describes artificial selection. Artificial selection Natural selection The individuals that are allowed to breed are chosen by humans These individuals have the characteristics that humans are interested in. This process produces animals that express some characteristics, such as a stubby snout, very strongly. The individuals that are best suited for survival are the ones that most likely will live long enough to reach reproductive age. This means that they are the ones that get to breed, and their characteristics (being good survivors) are inherited by their offspring. Artificial selection Natural selection 4. Natural selection is a process that creates animals that are increasingly well adapted to their environment and thus are good survivors. On the other hand, artificial selection produces animals that Check off the correct statement(s) Answer: Express a certain characteristic that humans prefer. Are not necessarily better survivors in the wild than their ancestors. Would probably not exist without human intervention. 4

5 Teacher s Guide 5. Find the nēnē or Hawaiian goose exhibit. The ancestor of the nēnē is a fairly well known goose species. Which species? Answer: The Canada goose 6. The table lists some of the characteristics that differ between the ancestral goose and the nēnē. Your job is to complete the table. Answer (suggestion): Characteristics Ancestral goose Nēnē Body posture (upright or horizontal) Shape of feet Horizontal Webbed Upright Webbing reduced, long toes Length of neck Long Relatively short Wing size Long, strong Shorter, less strong 7. Write in your own words how you think the nēnē characteristics were created by natural selection: Answer (suggestion): Nēnē posture Shape of nēnē feet Length of nēnē neck Nēnē wing size The nēnē lives on land, and rarely swims. The upright posture is better for walking. (The horizontal posture of a Canada goose is better for swimming.) The nēnē evolved with no land predators, so it never needed to swim to escape. Instead, the webbing on its feet is reduced so the long toes can grip uneven ground more easily. The nēnē feeds on land plants. Unlike its ancestor, it doesn t need a long neck to be able to reach plants underwater. The nēnē never leaves Hawai i, and only flies short distances. Over time, its wings have become shorter and less strong than its ancestor s. 8. Find the gharial exhibit. Gharials and dolphins give an interesting example of convergent evolution. Which feature do gharials have in common with dolphins? (Hint: think about what they eat!) Answer: A long slender snout full of equally sized, cone-shaped teeth. This is an adaptation for catching fish. 5

6 Teacher s Guide 9. Do the following pairs of animals give examples of convergent or divergent evolution? Convergent Divergent and and and and 6

7 Did you know that all dog breeds originated from the same ancestor? The ancestor of modern dogs was probably a wolf-like type of dog. Wolf-like ancestor Yorkshire terrier Golden retriever Cocker spaniel Poodle Most modern dog breeds, like the four shown above, have been created by humans. But how were the breeds created? Consider this scenario: The first primitive dogs were probably wolf-like animals that hung around human settlements to find food scraps. But where there are human settlements, there are often also rats. At some point, humans in these settlements probably noticed that some dogs were very skilled at catching rats. 1. Which characteristics might these rat-catching dogs have had, in your opinion? Quick or Slow Aggressive or Docile Large or Small The humans in the settlements might have taken special care of these rat-catchers. They might even have bred rat-catching female dogs with rat-catching male dogs. 2. If the rat-catching dogs had the characteristics (speed, size, and temper) that you checked off above, what would the consequences for their offspring be? Check off the correct statement(s) The offspring would probably inherit those same characteristics The offspring would probably be good rat-catchers Humans might have taken extra care of the offspring because of their usefulness 7

8 Imagine what would happen if humans kept breeding rat-catchers with rat-catchers, generation after generation. The end result would be a small, quick, aggressive type of dog, not because humans wanted a small, quick, aggressive dog, but because they wanted a good rat-catcher, and those are the characteristics of a good rat-catcher. There are several examples of such rat-catchers today! Most terriers were actually originally bred as rat-catchers, and if you ve ever known a terrier, you ll know that they are indeed small, quick, and aggressive. The process of crossing animals with certain characteristics with other animals with those same characteristics is called selection. When humans control the process, it is called artificial selection. The process of selection happens in nature, too. In this case, it is called natural selection. 3. What s the difference between artificial selection and natural selection? Below, you ll find two scenarios. Indicate which one is natural selection, and which one describes artificial selection. Artificial selection Natural selection The individuals that are allowed to breed are chosen by humans These individuals have the characteristics that humans are interested in. This process produces animals that express some characteristics, such as a stubby snout, very strongly. The individuals that are best suited for survival are the ones that most likely will live long enough to reach reproductive age. This means that they are the ones that get to breed, and their characteristics (being good survivors) are inherited by their offspring. Artificial selection Natural selection 4. Natural selection is a process that creates animals that are increasingly well adapted to their environment and thus are good survivors. On the other hand, artificial selection produces animals that Check off the correct statement(s) Express a certain characteristic that humans prefer. Are not necessarily better survivors in the wild than their ancestors. Would probably not exist without human intervention. Now, let s look at some animals that have evolved through natural selection! Go to the next page 8

9 5. Find the nēnē or Hawaiian goose exhibit at the Zoo. The ancestor of the nēnē is a fairly well known goose species. Which species? Natural selection Answer Ancestor of nēnē Nēnē The ancestor of the nēnē was originally from North America. It arrived at the Hawaiian Islands about 500,000 years ago. Since arriving here, the goose changed its appearance from the ancestral form to the present form: the nēnē. Let s look closer at some of these changes! 6. The table lists some of the characteristics that differ between the ancestral goose and the nēnē. Your job is to complete the table. Characteristics Ancestral goose Nēnē Body posture (upright or horizontal) Length of legs Webbing of feet Length of neck Wing size 9

10 Now, let s think of how these changes came about. What caused this selection to happen? Think about the different habitats the ancestor and the nēnē occupy, and the different behaviors they have as a result of this. Ancestor Lives in marshes, near water Feeds on aquatic plants Has many terrestrial predators Migrates over long distances every year Nēnē Lives on land Feeds on terrestrial plants Had no terrestrial predators for thousands of years Migrates only over very short distances 7. Write in your own words how you think the nēnē characteristics were created by natural selection: Nēnē body posture Length of nēnē legs Webbing of nēnē feet Length of nēnē neck Nēnē wing size 10

11 When natural selection causes one animal species to split into two (or more) species in this manner, it can be illustrated in the following way: Ancestral species (Canada goose) Canada goose Nene This process is called divergent evolution. To diverge means to become dissimilar or different, so when natural selection causes two species to become more and more dissimilar (as with the Canada goose and the nēnē), we call it divergent evolution. Another process is called convergent evolution. When two species develop the same adaptation, even though they are not related to each other, they converge (become more similar). 8. Find the gharial exhibit. Gharials and dolphins give an interesting example of convergent evolution. Which feature do gharials have in common with dolphins? (Hint: think about what they eat!) Answer: 11

12 9. Are the following pairs of animals examples of convergent or divergent evolution? Convergent Divergent and and and and 12