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Evolution is the process by which Populations accumulate inherited changes over time.

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Presentation on theme: "Evolution is the process by which Populations accumulate inherited changes over time."— Presentation transcript:

1 Evolution is the process by which Populations accumulate inherited changes over time.

2 Includes three major ideas: T heory of Evolution All organisms developed from a single life form that lived on Earth billions of years ago. All organisms share common ancestors. All species arise from other species.

3 Scientist have found evidence that all organisms on earth share a common ancestor…all organisms are related. Similar bone structure in the upper arm suggests these animals have a common ancestor. Common Ancestor

4 Mutations Natural Selection Two processes are necessary for populations to change over time.

5 Mutations are sudden changes in the DNA of a gene. These changes can be passed on from parent to offspring. Some mutations are helpful. Some mutations are harmful. Some are neither helpful or harmful. Mercury-Poisoning Mutation Harmful: Albinism is an inherited mutation. Albinos lack protective skin pigments therefore are prone to skin cancer and do not see well in bright light. Helpful: such as a mutation that causes bright color patterns in flower petals…all the better to attract pollinating insects. Mutation

6 Finches from the Galápagos Islands H.M.S. Beagle Five year voyage of H.M.S. Beagle ( ) In 1831 Charles Darwin (22 years old) voyaged on the HMS Beagle to the Galapagos Islands where he made many observations about the different species of plants and animals. He was most interested in the birds that lived in the different Islands. In 1859 he wrote a book called On the Origin of Species. In it Darwin presented his theory of evolution by natural selection. Charles Darwin

7 Survival of the Fittest Traits are selected Traits must be passed from one generation to the next Changes occur in response to the environment Natural selection is a process in which organisms that are better able to survive and reproduce in an environment are more likely to pass their traits on to future generations. Natural Selection

8 An adaptation is a characteristic or trait that helps an organism survive in its environment. Adaptation plays a major role in natural selection. An adaptation makes an organism more suited to its environment, and therefore more likely to survive and pass on its traits to the next generation. Adaptation

9 Some adaptations are body parts. Other adaptations are behaviors. A tigers teeth are adapted for tearing and chewing. A tigers fur helps it blend into tall grasses. Feathers are adaptations used for flight. A birds beak is adapted to the food it eats. What type of food do you think this bird eats? Adaptations

10 Leaves of green plants are adapted to absorb sunlight. Flowers are adaptations that attract insects that can help a plant reproduce. How do you think a plants stem helps it survive? A cactus is adapted to life in a desert. Its thick stems store water. A waxy coating on the plant reduces water loss. Adaptations Cont.

11 A sea turtle retreats into its shell when it senses danger. What are some other adaptations of sea turtles? A dandelions seeds are easily dispersed by the wind. How do you think this adaptation help the plants species? How do you think this insect adapted to living in or near trees? Adaptations Cont.

12 Peppered Moths The European peppered moth often rests on the trunk of trees and is found in two colors: one light and one dark. Before 1850, most peppered moths were light. After 1850, industry created pollution that blackened the tree trunks. Light moths became rare, while the once-rare dark peppered moths became more common.

13 Which moths are better adapted to the tree that they are on? Adaptations of Peppered Moths

14 The light variety of the peppered moth on a birch tree trunk. The dark variety of the peppered moth on a birch tree trunk. Unpolluted Birch Forest

15 The light variety of the peppered moth on a soot- blackened tree trunk. The dark variety of the peppered moth on a soot- blackened tree trunk. Polluted Birch Forest

16 Evolution Mini Assessment Review __________ is the process by which populations accumulate inherited __________ over __________. Evolution changes time Three Major Ideas of the Theory of Evolution: Organisms developed from a single life form that lived on Earth billions of years ago. Organisms share common ancestors. Species arise from other species.

17 Two processes are necessary for populations to change over time: 1. __________2. ___________ Mutations Natural Selection __________ are sudden changes in the ______________ of a gene. These changes can be passed on from parent to offspring. Mutations DNA Evolution Mini Assessment Review

18 __________ in 1859 wrote a book called On the Origin of Species, it was about __________ by __________ selection. Charles Darwin evolution natural __________ is a process in which organisms that are better able to survive and reproduce in an __________ are more likely to pass __________ traits on to future generations. Natural selection environment favorable (good traits)

19 Evolution Mini Assessment Review An __________ is a characteristic or trait that helps an organism survive in its environment. Adaptation A species can become __________ if its environment changes to quickly. extinct


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