CHAPTER 3 4 SECTIN Adapting to the Environment Adaptations and Survival EFRE YU READ After you read this section, you should be able to answer these questions: What adaptations help animals survive? What is a genetic bottleneck? Tennessee Science Standards LE 0807.5.3 LE 0807.5.4 LE 0807.Inq.5 How Are Animals Adapted To Their Environments? Sea turtles are strong swimmers because they have flippers. Sea turtles are also excellent divers. Leatherback sea turtles can dive to depths of more than 1000 m! The characteristics described above are called adaptations. An adaptation is a characteristic that improves an individual s ability to survive and reproduce in a particular environment. The abilities to swim fast and to dive to great depths can help sea turtles escape their predators and search for food. Although sea turtles lay their eggs on land, they are aquatic animals. Therefore, sea turtles have adaptations for an aquatic environment. They could not survive in only a land environment. All organisms have adaptations to help them obtain food. The figures below show just a few of the many adaptations found in the animal kingdom. STUDY TIP Learn New Words As you read this section, circle words that you don t understand. When you learn what they mean, write the words and their definitions in your notebook. Say It Investigate Pick an animal to research. Find out what adaptations this animal has that help it find food and protect itself. Share your findings with a small group. The chameleon (above) catches an insect with its long tongue. The woodpecker (right) uses its strong beak to drill holes into trees to find insects. Interactive Reader and Study uide 59 Adapting to the Environment
SECTIN 2 TAKE A LK 1. Compare How does the range of foods eaten by generalists and specialists differ? READIN CHECK 2. Identify What colors are common warning colors among animals? DIFFERENT TYPES F DIETS Some animals are adapted to eating one type of food. These animals are called specialists. ther animals can eat many types of food. These animals are called generalists. roup Description Examples Specialists eat one or very few kinds of food pandas, koalas, monarch butterflies eneralist eat many kinds of food black bears, humans, rats How Do animals Avoid eing Eaten? Many organisms have adaptations that serve as a defense against predators. Some organisms, such as the porcupine, have protective covering. right markings also warn potential predators to leave an organism alone. Patterns with black stripes and red, orange, or yellow markings are common in many species of animals. TAKE A LK 3. Color Use colored pencils to color in the coral snake so that it would appear dangerous to predators. The protective quills of the porcupine (left) keep predators away. The pattern of black, red, and yellow on the coral snake (right) is a warning sign to predators. This rabbit has long back legs that help it quickly run away from predators. Interactive Reader and Study uide 60 Adapting to the Environment
SECTIN 2 CAMUFLAE Another adaptation that helps both predators and prey is called camouflage. An organism that is camouflaged is disguised so that it is hard to see even when the organism is in view. Some predators use camouflage to sneak up on prey. Some animals can change their appearance over time. For example, some chameleons can change their color very quickly to match their surroundings. ther animals like the arctic fox change colors slowly. The arctic fox has white fur in winter to blend in with its snowy environment. During summer the snow melts, so the fox sheds its white fur, and becomes brown. READIN CHECK 4. Explain Why does the color of the arctic fox change during the year? Camouflaged by duckweed, this alligator can hide and wait for its prey. How Do rganisms Help Each ther? Two species can also be adapted to interact with one another. For example, some birds, called honeycreepers, have long, curved beaks. Having a long beak lets a bird sip the nectar at the base of the long, curved flowers. As a bird sips nectar from the flower, the bird gets pollen on its head. When the bird moves to another flower, some of the pollen will rub off. oth the plant and the bird benefit. Animals have also adapted to interact with other animals. Clownfish have adaptations that allow them to touch sea anemone tentacles, which normally sting. The clownfish chase off smaller fish that try to eat the sea anemone. In turn, the clownfish is protected from its own predators by the stinging tentacles of the anemone. Each animal gains protection from the other. Critical Thinking 5. Apply Concepts Name another type of animal that might help a plant to reproduce by carrying pollen. Explain how. Interactive Reader and Study uide 61 Adapting to the Environment
SECTIN 2 READIN CHECK 6. Identify Name two factors that play a role in whether an organism reaches adulthood. What Is Natural Selection? As you have learned, adaptations help organisms survive. rganisms inherit adaptations and other characteristics from their parents. However, inherited characteristics in populations can change over time. The change in the inherited characteristics of a population over time can be explained by natural selection. Natural selection is a process in which individuals with a certain trait survive and reproduce, but individuals without the trait do not. Individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do. Inherited characteristics may influence which individuals reach adulthood and which do not. Environmental factors such as predation and food availability also pay a large role. The scientists are counting sea turtle eggs. ne female can lay up to 200 eggs. nly some baby sea turtles will survive to reproduce. Those that do will pass on their traits to future generations of sea turtles. READIN CHECK 7. Identify What is genetic variation? What Happens To enetic Variation ver Time? ver time, a population will be made up of more individuals with characteristics that help them survive. For natural selection to act, individuals in the population must have some differences in their inherited characteristics. These differences are called genetic variation. However, if a population decreases rapidly, many characteristics may disappear from a population. Characteristics are lost if all individuals with those characteristics died. Interactive Reader and Study uide 62 Adapting to the Environment
SECTIN 2 A ENETIC TTLENECK When a population loses some of its variation in traits, it is in a genetic bottleneck. If the population begins to grow, all the individuals will have the same characteristics. A population with little genetic variation may suffer from birth defects and genetic diseases. Many individuals would likely be affected by the same disease. Large cats called panthers or cougars used to live in Tennessee and much of the southeastern United States. ecause of hunting and habitat loss, they are now found only in southern Florida. There are very few Florida panthers that live in different parts of Florida. This isolation and the decrease in population size have caused genetic variation within the Florida panther population to decrease. As a result, many of the panthers that survived have become genetically similar. reeding between individual panthers that are genetically similar can result in heart defects, the failure of reproductive organs, and low birth rates. However, there is a recovery program in place for the Florida panther. The program includes protecting and enlarging the panther s habitat as well as monitoring the health of the population. READIN CHECK 8. Identify What happens to genetic variation when there is a genetic bottleneck? P P ottleneck Population size Y Y Y Y Time Each color represents a different skin color within a population of frogs. When the population is reduced to a few members, a genetic bottleneck occurs. When the population grows, there are fewer colors of frogs. Math Focus 9. Calculate Suppose that each letter in the figure represent the different colors that a species of frog can be. What percentage of frogs in the initial population was green? What about the final population? Show your work. Frog Colors Y Yellow reen P lue range Purple Interactive Reader and Study uide 63 Adapting to the Environment
Section 4 Review LE 0807.Inq.5, LE 0807.5.3, LE 0807.5 SECTIN VCAULARY adaptation a characteristic that improves an individual s ability to survive and reproduce in a particular environment natural selection the process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well-adapted individuals do 1. Explain How does genetic variation help a population survive? 2. List Identify three adaptations that help animals avoid being eaten. 3. Apply Concepts What would happen if an animal moved to a new environment? 4. Identify Tigers often live in grasslands, with plenty of tall grass. How might a tiger s stripes help the tiger hunt for food? 5. Explain Suppose there are two types of a species of rabbit: one is white and the other is brown. If Earth becomes warmer and there is less snow, which rabbit is more likely to survive and reproduce? Explain your answer. Interactive Reader and Study uide 64 Adapting to the Environment