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NAME ___________________________________________ DATE ______________________________ Adaptations and Natural Selection PURPOSE: To determine how the environment and the process of natural selection produces adaptations in a population. BACKGROUND INFORMATION Natural selection is the powerful process by which certain inherited characteristics—those that make it more likely for an organism to survive and successfully reproduce —become more common in a population over many generations. It is a key mechanism of evolution and has resulted in some amazing adaptations in the natural world, such as the thick body armor of the armadillo. Adaptations are any physical or behavioral characteristic of an organism that increases its chances of survival in an ever-changing environment. The relationship between adaptations and the process of natural selection is often misunderstood, and many students develop the misconception that natural selection gives organisms their unique traits for enhanced survival. Rather, it is the chance appearance of the characteristic through mutations and gene shuffling which sets the stage for the process of natural selection to occur. Organisms which by chance possess a unique characteristic that increases the chances for survival in a particular environment will live to pass on the characteristic to subsequent generations, while other organisms without the characteristic will eventually die out. Thus, the favorable characteristic becomes an adaptation in the generations that follow, thereby changing the genetic makeup of the population over time. 1) Where do adaptations come from? ____________________________________________________ 2) How is natural selection connected to adaptations? _______________________________________ ________________________________________________________________________________ 3) What does the population’s environment have to do with a particular adaptation? ________________________________________________________________________________ 4) How does an environmental change (ex. hurricane, drought, etc.) affect the organisms that are adapted to the environment before the change? PROCEDURE: Specific physical and behavioral adaptations are described in the tables below. Some of the information has been removed. Fill in the blanks using the following information. A. B. C. D. E. F. provides required nutrients organism blends in with the environment hibernation gets rid of excess heat temporary hot, dry conditions leaves are spines ORGANISM PHYSICAL CHARACTERISTIC African elephant large, flat ears leaf bug body shaped and colored liked a leaf prickly pear cactus Venus fly trap plant traps insects in leaves frogs and toads (hibernation by burrowing) Alaskan brown bear estivation FUNCTION ENVIRONMENTAL STIMULUS hot climate avoid detection predation reduces water loss and provides protection hot, dry environment nutrient-poor soil keep body cool, conserves water survival in long winters cold climate ADAPTATION EXPLANATION easy and efficient method for keeping body cooled structure allows for conservation of water and increases chances of survival two methods for acquiring food (nutrition) provides for improved health need for water reduced; body temperature kept in homeostasis while in the ground little need for food, water since energy requirement is low ANALYSIS 1) The color and pattern of the viceroy butterfly’s wings mimics the monarch butterfly's appearance except for a black horizontal stripe that crosses the bottom of the back wings. Predators of the monarch butterfly quickly discover an important difference between these two, however: the monarch butterfly is poisonous and tastes terrible! How can the appearance of the viceroy butterfly’s wings be considered an adaptation? 2) The tails of many lizards, including the leopard gecko, is used as fat storage for times when there is not much food available in their environment. When grabbed by a predator, the tail breaks off and continues to flop around and wriggle long after it has dropped off the lizard's body. How is this phenomenon related to adaptations and natural selection?