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Adaptation & Variation

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Presentation on theme: "Adaptation & Variation"— Presentation transcript:

1 Adaptation & Variation
Learning Objective: Explain how an organism’s adaptations help it survive. Explain how variations within a population affect the survival of the population. Explain how structural adaptations are used to identify organisms.

2 Behavioral Adaptations
Behavioral adaptations help an organism survive and reproduce. Explain to students that every organism has unique adaptations. Ask: What are adaptations? Answer: Adaptations are behaviors and physical characteristics that allow organisms to live successfully in their environment. Ask: What is the definition of a behavioral adaptation? Click to reveal the definition. Ask a student to read the definition aloud. Direct students’ attention to the picture. Have a volunteer locate the egret in the picture. Click to reveal the circle around the egret. Ask students what the egret is doing in the picture. Guide students to understand that it is spreading its wings to hunt for prey in the water. Ask: How is this a behavioral adaptation? Answer: It is a behavior that blocks out the sun’s glare and makes it easier for the egret to spot and catch prey in the water. Click to reveal the circle around the fish. Ask: What is this organism and what is it doing? Answer: It is a fish that is swimming. Tell students that organisms are born knowing how to perform certain behaviors. Fish, for example, know how to swim from the moment they are born. Other behavioral adaptations are learned through practice and experience.

3 Adaptations Physiological adaptation: Structural adaptation:
A biochemical function that makes an organism better suited to its environment A physical characteristic that allows an organism to survive in its environment Kidneys produce concentrated urine. Explain to students that in addition to behavioral adaptations, plants and animals also have structural and physiological adaptations. Ask: Why is it beneficial that each organism has a variety of adaptations? Answer: Variety helps the organism survive the different factors it encounters in its environment. Ask students what organism is shown in the photo. Encourage students to identify the organism. Tell them that it is a kangaroo rat. Direct students to the two examples of adaptations. Tell students: These are two examples of adaptations for a kangaroo rat. Ask students to determine whether the examples are structural or physiological adaptations. Click to match the examples with the type of adaptation. Ask students to think about the structural adaptation example. As a class, brainstorm a definition for structural adaptation based on this example. Help students understand that a structural adaptation is a behavior that an organism has. Click to reveal the definition of structural adaptation. Discuss the example of the physiological adaptation. Help students understand that a physiological adaptation is a biochemical function in an organism. Explain that since kangaroo rats live in the desert, their kidneys can produce very concentrated urine to conserve water. As a class, brainstorm a definition for physiological adaptation based on this example. Click to reveal the definition of physiological adaptation. Ask: How do the rat’s internal structures function to help it survive in its environment? Answer: Its kidneys can conserve water, helping the rat survive with limited amounts of water in the desert. Fur color blends in with the surroundings.

4 The Human body’s ability to maintain a constant internal temperature
Structural adaptation: Physiological adaptation: The Octopus uses its tentacles to capture prey The Human body’s ability to maintain a constant internal temperature

5 Adaptations may work together to ensure the organisms survival!
Behavioral A lions ability to stalk and take down prey Structural A lions teeth and claws allow the lion to capture and eat prey Physiological A lions ability to grow teeth and claws

6 The Importance of Variation
Variations can affect the survival of a population. During the drought, only the medium ground finches with beaks survived. larger, stronger Explain to students that offspring often inherit variations from their parents. A variation is a difference among individual organisms, such as beak size and strength. Ask: How does natural selection result in variations being common in a population? Answer: Individuals that have a well-suited variation are more likely to survive and reproduce. They pass the variation on to their offspring. Individuals that lack the variation are less likely to survive and reproduce, so the next generation will have more individuals with the variation. Remind students that an organism does not change its traits to fit the environment. Tell students that during a serious drought on one of the Galápagos Islands, many small-seed plants died. As a result, the normal food supply became scarce. Another plant on the island thrived during the drought. It produced seeds that were large and difficult to open. Medium ground finches with the smallest and weakest beaks could not crack these larger seeds. They competed for the limited amount of smaller seeds and many died. The finches with larger and stronger beaks had less competition for the larger seeds, and they survived. Ask: What happened when the finches with the larger, stronger beaks reproduced? Answer: They passed this variation to some of their offspring. To review, click to reveal the statement. Ask a student to read the statement aloud. Have a volunteer say the missing phrase aloud. Click to reveal the answer.

7 The Importance of Variation
Variations help individuals survive better in their environment. When a species survives and reproduce, the population survives.

8 What is behavior Explain what causes animal behavior.
Describe instinctive behaviors and identify the four kinds of learned behavior.

9 What Causes Animal Behavior?
Stimulus: A that causes an organism to react in some way Response: An organism’s reaction to a signal stimulus Tell students that all animal behaviors are responses to stimuli. Help students recall that a stimulus is a signal that causes an organism to react in some way. Tell students that the organism’s reaction to the stimulus is called a response. Most behaviors help an animal survive or reproduce. Explain that certain moths have markings on their underwings that look like the eyes of an owl. When the moth is frightened by a predator, it raises its forewings to reveal the “eyes.” Have a volunteer point to the “eyes” on the moth’s underwings. Click to reveal the definition for stimulus. Ask a volunteer to complete the definition for stimulus. Click to reveal the missing word. Click to reveal the definition for response. Ask a volunteer to complete the definition for response. Ask: How is this moth’s behavior important to its survival? Answer: The “eyes” of the moth look like the eyes of a much larger animal and may scare a predator. Have students think of other stimuli and responses.

10 What Are the Types of Animal Behavior?
Learned behavior Instinctive behavior A response to a stimulus that is performed correctly the first time Tell students that there are two types of behaviors: instinctive behaviors and learned behaviors. Explain to students that instinctive behavior is inborn, which means that the animal is born with the ability to carry out that behavior. Learning is the process that leads to changes in behavior based on practice or experience. Because learned behaviors result from an animal’s experience, they are not usually done perfectly the first time. Click to reveal the definitions. Ask a volunteer to read the definitions aloud. Ask students which definition goes with each term. Click to reveal the correct matches. Ask: Is a spider spinning a web an instinctive behavior or a learned behavior? Answer: instinctive behavior Click to reveal the answer. Some students may think that only simple behaviors are instinctive. Explain to students that many instinctive behaviors are complex. Spiders that spin orb-webs do so using different types of silk secreted by spinning glands. Some of the threads are not sticky, while the threads in the center of the web are sticky. When prey is trapped in the web, the spider responds to the stimulus of vibrations it feels in the web. The spider moves along the threads that are not sticky to inject venom into the prey. This behavior is instinctive. Ask: Could the spider survive without the instinct to spin a web? Why or why not? Answer: No; if the spider could not spin a web, the spider would not be able to catch food. A response that is based on practice or experience Instinctive behavior Instinctive

11 Learned Behaviors Learned behaviors result from experience and practice. Instinctive Pouncing Learned Catching prey Invite volunteers to describe a behavior they learned in the past week. Students may cite examples of athletic activities, learning to sing or play a new song, or improving skills at a computer game. Ask: What is learning? Answer: the process that leads to changes in behavior based on practice or experience Click to reveal the photo. Explain to students that the cheetah cub in the photograph was born with physical characteristics and instincts that are necessary for hunting. It has claws that help it capture prey. It also has an instinct to pounce on any object that attracts its attention. However, only through experience can it learn hunting skills. Click to reveal the “pouncing” and “catching prey” terms and their write-on-lines. Ask a volunteer to write which behavior is learned and which is instinctive. Click to reveal the correct answer. Ask students how they think parents teach their cubs to hunt. If students cannot suggest an answer, explain that a parent may catch a small animal and give it to the cub to practice on. Cubs also learn by watching their parents hunt.

12 Types of Learned Behaviors
Conditioning Insight learning Trial-and-error learning Imprinting Imprinting: Newly hatched or newborn mammals recognize and follow the first moving object they see. Tell students that learned behaviors includes imprinting, conditioning, trial-and-error learning, and insight learning. Ask students to describe what they see in the picture. Explain that the picture describes the fourth type of learned behavior: imprinting. Click to reveal “imprinting” and its definition. Ask a student to read the definition aloud. Explain that Konrad Lorenz, the man in the picture, was an Austrian scientist who conducted experiments in which he, rather than the parent, was the first moving object that newly hatched birds saw. Helps students understand that imprinting is a combination of instinctive behavior and learned behavior. Ask: Which part of imprinting in geese is instinctive? Answer: following the first thing they see move Ask: What part of imprinting in geese is learned? Answer: knowing which thing to follow Ask: How does following a parent help young animals survive? Answer: It keeps the young animals close to the parent, who will protect them and feed them or help them find food. It helps them learn what individuals of their own species look like.

13 Conditioning Learning that a particular stimulus or response leads to a good or a bad outcome Response Ask a student to read the definition of conditioning aloud. Explain to students that pets are often trained using conditioning. At first, a puppy rarely comes when you call. But every now and then, the puppy runs to you in response to your call. Each time the puppy comes, you give it a dog biscuit. Your puppy will soon learn to associate the desired response—coming when called—with the good outcome of a food reward. During the early 1900s, the Russian scientist Ivan Pavlov performed experiments involving one kind of conditioning. The following images show the steps that Pavlov followed in his experiments. Click to reveal an image showing a dog salivating in response to food. Explain that when a dog sees or smells food, it produces saliva. Ask: What was the original stimulus in the experiment? Answer: the smell of the food Click to reveal the label “stimulus” pointing to the dog food. Ask: What was the response? Answer: salivating Click to reveal the label “response” pointing to the dog salivating. Click to reveal the next panel. Explain to students that for many days, Pavlov rang a bell every time he fed a dog. The dog learned to associate the ringing of the bell with the sight and smell of food. Click to reveal the third panel. Explain that in time, when Pavlov rang a bell but did not feed the dog, the dog still produced saliva. The new stimulus produced the response that normally only food would produce. Ask: What response did the bell cause? Answer: salivation Ask: What kind of learning is this? Answer: conditioning Ask: What might the dog do if the doorbell rang? Answer: It might salivate because it heard a bell. Explain to students that household pets often become conditioned to expect food when certain stimuli are present. Ask: What kinds of stimuli can make a pet expect food? Sample answers: the sound of a can opener, the clink of the pet’s dish, the opening of the container or cabinet where food is stored Stimulus

14 Trial-and-Error Learning
Learning to do a behavior through repeated practice The dog attacked a porcupine and learned that the quills are painful. Ask students if they have heard the expression, “If at first you don’t succeed, try again.” Explain to students that when they learned to ride a bicycle, they did it by trial and error. They may have wobbled at first, but eventually they got better. Many animals learn by trial and error which methods are best for obtaining food. They also learn which methods to avoid. Click to reveal the picture. Invite students to share their ideas about what happened to this dog. Click to reveal the answer. Explain to students that nobody tells a bird to look for food in one place and not another. Ask: What happens if a bird finds tasty berries on a particular kind of bush? Answer: The bird will learn to go back to that bush and look for more berries. Ask: What happens if a bird looks for berries on a different kind of bush and gets stuck by thorns? Answer: The bird will learn to avoid that kind of bush in the future.

15 Insight Learning Learning how to solve a problem or do something by applying what you already know, without a period of trial and error Ask a student to read the definition of insight learning aloud. Tell students that pets are often trained using insight learning. Click to reveal the three-panel example. Read the text in the first panel aloud. Click to reveal the text in the second panel. Read the text aloud. Click to reveal the text in the third panel. Discuss the example with students. Ask students to use their own words. Ask: What did Betty already know how to do? Answer: She knew how to use a curved wire to pull up the bucket of food. Ask: Who taught Betty to bend the straight wire? Answer: Nobody; she figured it out by herself. Ask a student to point to the panel that shows Betty bending the wire to solve the problem. Click to circle the second panel. Explain that insight learning is most common in primates, such as gorillas, chimpanzees, and humans. For example, chimpanzees use twigs to probe into the nests of termites and other insects that they eat. The chimps use insight to bend or chew their twig “tools” into a shape that will best fit the holes. Betty is a New Caledonian crow. So far, this is the only species of crow that has been found to exhibit insight learning. New Caledonian crows can be found in New Caledonia, a self-governing territory of France located in the southern Pacific Ocean between Australia and New Zealand.

16 What Is Behavior? Overview
Trial-and-error A dog is taught to salivate when a bell rings. Instinct A dog avoids skunks after one encounter. Conditioning A crow figures out how to use a wire to get food out of a tube. Have students review what they have learned about behavior by matching the terms with the appropriate examples shown. Click to reveal the correct matches. Imprinting Newly hatched geese follow a human. Insight learning Cheetahs pounce on prey.

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