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The Theory of Evolution Why do we say Theory? What is Evolution? • Evolution is a process by which modern organisms have descended from ancient organisms. It is a change in population (not individuals) over long periods of time. • Evolution is also called descent with modification. Evolution Videos • Evolution of Dance • https://www.youtube.com/watch?v=dMH0bH eiRNg • Evolution of Video Games • https://www.youtube.com/watch?v=WYJoaV MzQYc • Evolution of Cell Phones • https://www.youtube.com/watch?v=JcnXOhr mDB8 • (look for pentatonix evolution of music) Think Back • Remember the videos? • What did we see that evolved? • Why is Pokemon a bad example? Important Vocabulary for Evolution Evolution = A change in populations and not individuals over long periods of time. Scientific Theory = well-supported, testable explanation of phenomena that have occurred in the natural world. Fitness= the ability for an organism to survive and reproduce in its environment. It’s a result of adaptation. Adaptation= any inherited characteristic that increases an organism’s chances for survival. Who is Charles Darwin? • An English Naturalist and Geologist best known for his contributions to the Theory of Evolution. • In 1831, Darwin set sail from England about the H.M.S. Beagle for a voyage around the world. At which time he made numerous observations and collected evidence that led him to propose a hypothesis about the way life changes over time based on natural selection. Darwin’s Pieces of Evidence • Evidence that living things have been evolving for millions of years includes: • The fossil record – Some of the fossils resembled organisms that were still alive. – Others looked completely unlike any creature he had ever seen. • Homologous, analogous, and vestigial structures • Embryology • Geographic distribution of living things • Biochemistry Darwin’s Theory of Evolution by Natural Selection What is Natural Selection? (also known as Survival of the Fittest) • Process by which individuals who are better adapted or most fit for their environment will survive and reproduce successfully. • In the Galapagos Darwin notices that there were variations among members of the same species. • Example: Finches, Giant Tortoise Example of Natural Selection – Peppered Moths The evolution of the peppered moth over the last two hundred years has been studied in detail. Originally, the vast majority of peppered moths had light coloration, which effectively camouflaged them against the lightcolored trees and lichens upon which they rested. However, due to widespread pollution during the Industrial Revolution in England, many of the lichens died out, and the trees which peppered moths rested on became blackened by soot, causing most of the light-colored moths, to die off due to predation. STOP! Moth Activity • Color the two white moths you picked up on your way into class. • You are trying to camouflage (disguise) them so they are well hidden from predators. • I will pretend to be a bird and go hunting for moths when the timer goes off. • You will receive extra credit on the test if you camouflage your moths well enough that I do not find them. Recap- Survival of the Fittest • Process by which individuals who are better adapted or most fit for their environment will survive and reproduce successfully. • Who had fit moths? How do you know? Based on Darwin’s Theory, who would be considered “fit”? Tim Tebow? Mama June? Mama June • Mama June is more fit according to Darwin’s Theory because she produced multiple offspring that survived. • Tim Tebow did not produce any offspring to carry on his traits so he is not considered fit according to Darwin’s Theory. Beak Size Activity • Get into groups of two. • Watch demonstration. • Design your own environment and record what happens for 5 generations. • You should write using detail. Minimum one full page. The Fossil Record What are fossils? Remains of once living organisms Like the hard parts of organisms (i.e. bones), impressions, or casts. Water carries small rock particles to lakes and seas. Dead organisms are buried by layers of sediment, which forms new rock. The preserved remains may later be discovered and studied. The Fossil Record: – Portrayed by remains of ancient life forms. – When fossils are discovered they can be added to the fossil record based on age and similarities. – Found mainly in Sedimentary Rock Homologous Structures • Similar in structure but functions differently • Examples: flying, swimming, grasping etc. Analogous Structures • Structures that have a similar function, but different structures. Example: Butterfly and bird both use their wings for flying, but wings are structured differently, one has bones, one has network of veins. Vestigial Structures • Structures that serve no useful purpose in an organism. In whales, there is a vestigial pelvis and femur. In horses, there is a vestigial toe. In snakes, there are vestigial hips Can you name any vestigial structures in humans? Human Vestigial Organs • • • • appendix tailbone wisdom teeth male breast tissue and nipples Embryology: early stages in development align across species. Share a common ancestor Similarities in Embryology In their early stages of development, chickens, turtles, and rats look similar. This provides evidence that they shared a common ancestor. Biochemistry: DNA and Proteins • Closely related species share common genetic base sequences BIOGEOGRPAHY (GEOGRAPHIC DISTRIBUTION) • a study in which scientists study the location and distribution of plants and animals around the world, particularly on islands. For example: In Africa we find rhinoceroses, hippopotamuses, lions, hyenas, giraffes, zebras, chimpanzees and gorillas. South America has none of these. Instead, it is home to pumas, jaguars, raccoons, opossums and armadillos. Marsupials are found in Australia and South America, but not in Europe Let’s take a break- Island Activity • Today you will be finches. I will read you a story and you will act it out. • Everyone to the back of the room please. • This activity will be very similar to the beak size activity. Who influenced Darwin? • Darwin’s thoughts over Evolution were influenced by numerous people such as James Hutton and Charles Lyell (geologists)Thomas Malthus (an economist), and Jean-Baptiste Lamarck (a naturalist, like Darwin). Thomas Malthus Jean-Baptiste LaMarck Lamarck’s Idea of Acquired Traits: • He proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. He believed that these acquired traits could then be passed on to their offspring which led to a change in a species. You’ve Heard the Facts • Take 5 minutes to discuss Darwin’s 5 pieces of evidence with your elbow partner. • Which piece is the most convincing? • Come up with three strong arguments for your piece of evidence. • What questions do you still have? We know the evidence… What do we see? Types of Adaptations Adaptation: any inherited characteristic that increases an organism’s chances for survival. Hummingbirds have adapted to their environment in two ways: 1.Very fast flight to keep them steady. 2.Long beak and tongue to reach into flowers and extract nectar. REMEMBER… Fitness: the ability for an organism to survive and reproduce in its environment. It’s a result of adaptation. Types of Adaptations CAMOUFLAGE: An adaptation that allows organisms to blend into their environment. Example: ghekko blending in to avoid predation. Remember you camouflaged your moths so the bird wouldn’t eat them. Types of Adaptations MIMICRY: An adaptation that allows one species to evolve into resembling another species which often results in the species to often increase their fitness ability while also allowing them to escape possible predation. Example: Eastern Coral Snake/Scarlet King Snake or the Monarch/Viceroy Butterflies STOP! Chocolate! • If you want a piece of chocolate, take a piece as the bin is passed around. Do not eat it yet. • We will all eat the chocolate when I count to 3. Now that everyone has water… • • • • What was this an example of? All the chocolate looked the same. Did it all taste the same? Why did some of you run for the trash? Why is mimicry useful? • This is what happens when predators eat certain prey. They taste bad. It’s advantageous for a yummy prey to look like the nasty prey. Then the predators won’t want to eat them. Genetic Variation Based on modern knowledge of genetics, we NOW know that natural selection is dependent on genetic variation within the gene pool. Genetic variation allows diversity within a population. Gene Pool: consists of all the genes including all the different alleles that are present in a population. A population is a group of individuals that inhabit the same area. A species is a group of similar organisms that can breed and produce fertile offspring. Speciation: the formation of a new and distinct species in the course of evolution. Geographic Isolation: • When two populations of a species becomes separated by geographic barriers such as rivers or mountain ranges resulting in the formation of 2 separate gene pools. • Allopatric Speciation • Ex: Abert Squirrels vs. Kaibab Squirrels. MECHANISMS OF EVOLUTION Although natural selection remains a central theme in evolution, scientists NOW know that natural selection is NOT the only mechanism for evolution. One of those mechanisms is called the HARDY-WEINBERG PRINCIPLE which states that when an allele frequency remains constant, a population is in genetic equilibrium. Hardy (mathematician) and Weinberg (physician) both showed mathematically that evolution will not occur in a population unless allele frequencies are acted upon by forces that cause change. There are 5 conditions required to maintain genetic equilibrium: (1). Random mating (2) must have very large population (3) no movement into or out of population (4) no mutations and (5) no natural selection. Poker Chip Activity • Look at your hand outs and work with your group to complete the activity. • Please raise your hand to ask questions. Another mechanism is called Genetic Drift • a change in allele frequencies that occur in small populations. These changes are associated with random events . • There are 2 types of genetic drift: – founder effect • small group splinters off & starts a new colony – bottleneck • some factor (disaster) reduces population to small number & then population recovers & expands again Bottleneck Bottleneck Effect Example: A Diverse Population “Catastrophic Event” (hunting, earthquake, volcanic eruption, etc.) A Small % of the Original Population Remains & RePopulates A Less Diverse Population Genetic Drift by way of Founders Effect • Small population gets separated by chance (storm, earthquake, etc.) • Develop different adaptations over many generations • If they come in contact later, they are too different to interbreed • Ex. Galapagos finches fly to nearby island Gene Flow: the transfer of genes or alleles from one population to another. Gene Flow • Movement of individuals & alleles in & out of populations – seed & pollen distribution by wind & insect – migration of animals • sub-populations may have different allele frequencies • causes genetic mixing across regions • reduce differences between populations Human Evolution Today • Gene flow in human populations is increasing today – transferring alleles between populations Are we moving towards a blended world? Tiger Survival • Get into groups of two. • Make sure you have a work sheet, directions, and a bag of beans. Goldfish Genetic Drift • Get into groups of two. • Make sure you have a worksheet and a paper towel.